Waterfowl from the marine environment are a class of birds that have managed to adapt to life in that kind of salty environment. Although it is true that they are very different from each other, with regard to the kind of life they lead, as well as their character, behavior and physiology, it is common to observe that cases of convergent evolution have occurred. If you want to know more about Waterfowl, we invite you to continue reading.
waterfowl
As we mentioned before, in the different classes of aquatic birds that live in the marine environment, phenomena of convergent adaptive evolution have been found, which means that they have come to develop similar evolutionary adaptations in the face of problems of the same nature, in relationship with the environment, particularly with regard to their food niches.
The first aquatic living in the marine environment managed to evolve during the Cretaceous period, according to paleontological studies, but modern families have been proven to have their origin in the Paleogene period.
In general, waterfowl that live in the sea are very long-lived, which means that they have long life expectancies, they also reach sexual maturity to reproduce very late and fewer young individuals will be found in their populations, to which the adult specimens have to dedicate a lot of time, to be successful in their upbringing.
Many of the species of aquatic birds have the habit of nesting in colonies, which, depending on the species, can vary in number of individuals from a dozen birds to millions of them. Other species are known for making long annual migrations, which leads them to cross the equator and, in many cases, go around the earth.
This class of birds are able to feed on the surface of the ocean or have the ability to dive and obtain food from the depths, or they can do it in both ways. Some species are considered pelagic, which means that they are coastal, while other species spend a large period of the year completely away from the sea.
The morphology of aquatic birds in the marine environment will be conditioned by multiple factors. An example of this is the symmetry of the body of birds, which is a consequence of the type and function of their flight, which can be grouped into categories of hunting, movement to nesting or breeding sites, and migration.
An aquatic bird has, on average, a body mass of around 700 g, a wingspan of 1,09 m and a total wing area of 0,103 m². However, these measurements will depend on the flight mechanism and the origin of the species.
The aquatic birds that live in the sea have maintained a long history of coexistence with man, since since time immemorial they have been part of the diet of hunters, fishermen have used them to find fishing banks and have been able to of managing to guide the sailors towards the coasts. Because several of these species are threatened by human activities, movements in favor of environmental conservation study them a lot and are aware of them all the time.
Waterfowl Classification
We have to tell you that there is no single definition with which to establish which groups, families and species are waterfowl of the sea and most of them, in some way, can be considered as arbitrary classifications. The name waterfowl or seabird has no taxonomic value; it is simply a grouping, which could be considered a bit artificial, which is not used in the scientific fields of classification.
What one might think is that it is a kind of popular taxonomic classification, since it encompasses many taxonomic groups, although it excludes some species. Perhaps the only peculiarity that these birds have in common is that they feed in large expanses of seawater, but, as is the case with most statements used in biology, some do not.
In a conventional way, it is possible to classify as waterfowl of the marine environment all the sphenisciforms and procellariiforms, as well as all the pelecaniformes, with the exception of the aningids and some caradriforms, among which are the stercorariids, lárids, sterids, alcids. and corners. It is common that the phalaropes are also included, because, despite the fact that they are wading birds, two of their three species are oceanic for nine months a year, a period in which they cross the equator and feed in the sea. opened.
Also included are the gaviformes and podicipediforms, which make their nests in lakes, but spend the winter in the sea, so they are categorized as waterfowl. Although there are some mergynes that are included in the Anatidae family, which are actually marine in winter, they have been excluded by convention from this classification. Many waders and herons could be considered marine, because their habitat is on the coast, but they are not classified in this way.
Evolution of Aquatic Birds and the Fossil Record
Aquatic birds that live in the sea, due to the fact that they spend their lives in sedimentary environments, that is, in habitats in which there is an almost permanent sedimentation of materials, are very well represented in the fossil record. knowledge that they had their origin in the Cretaceous period.
An example of this is that the hesperornithiformes belong to this period, which are a group of birds that did not fly, that were similar to loons, that had the ability to dive in a similar way to these and the loons, using their legs to move underwater, although this Cretaceous family had a beak with sharp teeth.
Although the hesperornis do not seem to have left any offspring, the first modern marine waterfowl also arose in the Cretaceous period, with a species that has been called Tytthostonyx glauconiticus, which seems to be related to the procellariiforms or the pelecaniformes.
In the Paleogene period, the seas are dominated by the first procellariids, giant penguins and two extinct families, which were the Pelagornithidae and the Plotopteridae, which were a group of large birds similar to penguins. The modern genera began to expand in the Miocene period, although the puffinus, which encompasses the now known Maned shearwater and Sooty shearwater, date from the Oligocene epoch.
The great variety of waterfowl living in the sea apparently had its origin in the late Miocene and Pliocene period. At the end of the latter, the oceanic food chain was modified, due to the fact that a great extinction of the number of species occurred, as well as a great expansion of the number of mammals in the sea, aspects that prevented aquatic birds from recovering its former diversity.
Waterfowl Characteristics
The characteristics of aquatic birds that live in the sea are various, so we are going to try to explain each of them:
Adaptations for maritime life
Cormorants, like the long-eared cormorant, exhibit a layer of feathers that is unique, because they allow less air to pass through, but still manage to absorb water. This adaptation allows them to thermoregulate and fight against natural buoyancy.
The aquatic birds of the sea have many adaptive evolutions to be able to live and feed in the oceans. The shape of their wings has originated from the niche in which they evolved, in such a way that when a scientist looks at them, they will be able to recognize information related to their behavior and feeding.
In fact, long wings and low wing loading are particular to a pelagic species, whereas birds that are divers will exhibit shorter wings. Some species, such as the traveling albatross, which finds its food on the surface of the oceans, have a reduced capacity for self-propelled flight and depend on a kind of gliding called dynamic, in which the wind deflected by the waves cause the bird to rise, as well as to glide up or down.
The case of several alcids, penguins and petrels exhibit wings with which they can swim under the sea and in some cases, such as penguins, they do not have the ability to fly. These birds are not capable of diving up to 250 meters and can store oxygen, either in air sacs or through the myoglobin in their muscles.
Penguins have a larger blood volume, which makes it easier for them to store more oxygen. At the time of having to dive, they are also able to slow down their heart rate and bring blood only to their vital organs. Almost all waterfowl that live in the sea have webbed feet, which allows them to move easily on the surface and, in the case of several species, diving.
Procellariiforms have a sense of smell that is unusually strong for a bird, and they use it to find food on the vast surfaces of the oceans, and probably also use it to locate their colonies.
The supraorbital glands that aquatic birds of the sea have allow them to osmoregulate and eliminate the salt that they ingest when drinking and feeding in these waters, especially if they are crustaceans. The excretions of these glands, which are located in the area of the bird's head, arise from its nasal cavity and are almost entirely sodium chloride, although small proportions of potassium and bicarbonate can also be found, along with a minimal portion of urea. .
These glands are under the control of the parasympathetic nerve and their activity can be stopped with anesthesia and drugs such as carbon dioxide inhibitors. This is an adaptive evolution that has been fundamental, because the kidneys of these birds do not have the capacity to process and eliminate these high concentrations of salt.
Although it is true that all birds have a nasal gland, it is not as developed as that of cormorants or penguins. Moreover, marine waterfowl have supraorbital glands ten to one hundred times larger than those that land birds have, because this will depend on the amount of salt to which they are exposed in their journey and feeding.
Hyposmotic regulation, that is, the mechanism by which organisms that have their habitat in extremely salinity conditions manage to conserve themselves, can also occur through the reduction of trigger flows, as is the case of urine, which is reduced, to avoid losing water from the body unnecessarily.
With the exception of cormorants and several terns, and similar to most birds, all waterfowl that live in the sea have plumage that resists water. However, when compared to land-dwelling species, they have more feathers, in order to protect their body. This dense plumage is what keeps the bird from getting wet; Likewise, this layer of down prevents the bird from being cold.
Cormorants exhibit a unique coat of feathers, because it lets less air through and as a result absorbs water, making it easier for them to swim without having to fight against buoyancy caused by air retention between the feathers, although They are also capable of retaining enough air to prevent them from losing too much heat when in contact with water.
The plumage of most of the aquatic birds of the sea, which by evolution has adhered to colors such as black, white or gray, is of course less colorful than the plumage of birds that live on land. Although some species exhibit colorful feathers, such as tropical waterfowl or certain penguins, but that color change will be found in the beaks and legs.
The plumage of aquatic birds that have their habitat in the oceans serves as camouflage, defensively, as is the case of the color of the plumage of the Antarctic duck-petrel, which was copied to paint the battleships of the United States Navy , manages to reduce its visibility at sea; while it may have an aggressive function in the case of the lower white section that many species have, which helps them hide from their prey below. The reason why the wing tips of this class of birds is black, due of an accumulation of melanin, is to be able to prevent the feathers from deteriorating, especially by friction.
Diet and Food
The aquatic birds that live in the sea managed to evolve to be able to find their food from the seas and oceans; moreover, their physiology and behavior have had to adapt to their diet.
These living conditions have caused species from different families, and even from different orders, to have managed to develop similar strategies in the face of the same environmental problems, which is an excellent example of convergent evolution, as can be seen between penguins and alcids. .
According to the studies carried out, it has been concluded that four basic strategies can be observed that birds use to feed in the sea, which are feeding on the surface, chasing food by diving, diving, and preying. larger vertebrates. Although, of course, between these four strategies multiple variations can be achieved.
surface feeding
Many species of waterfowl that live in marine environments obtain their food from the ocean surface, because the currents have the ability to achieve concentrations of food such as krill, forage fish, squid and other prey that may have within reach of its beak just by plunging its head into the water.
This methodology can be divided into two types: feeding on the surface of the water in full flight, something that petrels, frigatebirds and hydrobatids are capable of doing, and feeding while swimming, which is how they obtain their food. fulmars, gulls, various shearwaters and petrels.
Let's say that in the first category we are going to meet some of the sea water birds that are more acrobatic. Some are capable of taking their snacks from the water, as is the case with frigatebirds and some ternids, and others do a kind of walk and even manage to run around and circle above the surface of the water, as is the case with some hydrobatids.
Many of them do not even need to land in the water to feed, and some, like the frigatebirds, will have difficulty resuming flight if they land in the water. Another family that does not need to land in the water to feed is the Rynchopidae, which has a unique technique for hunting, since it flies very close to the water surface with its jaw open, which will automatically close when its beak touch something. That is why its beak reflects this kind of special hunting method and is that its lower jaw is longer than the upper one.
Within this group, many of the swimming birds also exhibit peculiar beaks, which have been adapted to house a particular class of prey. Birds of the Pachyptila and Halobaena genera have beaks with filters, called lamellae, with which they can filter plankton from the water they drink.
Many albatrosses and petrels have hook-shaped bills with which they can catch fast-moving prey. The gulls have beaks that are less specialized, which shows their lifestyle, which is more opportunistic. In the province of Buenos Aires, the gulls obtain a great benefit from the fishing activities and consume the young specimens of anchovy and yellow croaker. . The kelp gull is, within the group of larids, the one with the widest trophic spectrum; while Olrog's Gull is rather specialized.
pursuit dive
The chinstrap penguin is one of the species of waterfowl in the sea that pursues its food by diving. The pursuit dive is the one that requires the most pressure from the seabirds in relation to their physiology and their evolution patterns, but they obtain a reward that is to be able to have a greater feeding area than that of the birds that stay only on the surface.
They are able to propel themselves underwater with the help of their wings, as is the case with penguins, alcids, pelecanoids and some species of petrels, or propel themselves with their feet, as is the case with cormorants, loons, loons and some types of ducks that eat fish.
In general, wing-propelled birds tend to be faster than leg-propelled birds. But in both cases, the ability to use wings or legs to dive has had the effect of limiting their usefulness for other situations, as occurs with loons and loons, which walk with great difficulty, penguins that cannot fly and alcids that have lost the efficiency of their flight to be able to dive better.
An example of this is the common razorbill, which requires 64% more energy to fly than a petrel of equal size. Many species of shearwaters are somewhere between the two resources, since they have longer wings. than typical wing-propelled diving birds, but have higher wing loading than other surface-feeding procellariids; this gives them the ability to dive to great depths, while also allowing them to cover great distances efficiently.
Within this family, the best diving bird is the Tasmanian shearwater, which has been recorded swimming 70 meters below sea level. Several species of albatross are also capable of diving, albeit to a limited extent, while the sooty albatross can reach depths of 12 metres.
Of all the diving birds that are determined to chase their prey, the most efficient in the air are the albatrosses, and it turns out to be no coincidence that they are the worst swimmers. In the case of the polar and subpolar zones, this is the way that is most used by the aquatic birds of the sea to find their food, because it is not energetically feasible to do so in the warmer waters. Because they do not possess the ability to fly, many diving birds are more limited in their foraging range than others, particularly in the breeding season, when nestlings require regular feeding by their parents.
plummet
Gannets, boobies, fetontiformes, some ternids and the brown pelican are capable of diving from the air. This makes it easier for them to use the energy of that thrust to break the natural buoyancy line, which is caused by air becoming trapped in the plumage, and use less energy than other divers.
Thanks to this, they are able to use the food resources that are more widely distributed, particularly in the case of tropical seas that have been overexploited. In general, it is a more specialized way of hunting among seabirds; others that have more general habits, such as gulls and skuas, use it, but with less skill and from lower heights.
Brown pelicans take years to fully develop the skill required to perform the dive, once they have achieved it, they are capable of diving from 20 meters above the surface of the water and adapt their body before before the impact occurs, thus avoiding injuries. Another element that has been suggested is that this group of birds is only capable of hunting in clear waters, because they could have a better view of their prey from above. air.
Although this method is mostly used in the tropics, the link between this technique and water clarity has not been fully demonstrated. Several species that use this technique, as well as surface-feeding birds, depend entirely on the tuna and dolphins that are the ones that take the schools to the surface, to be able to feed.
Kleptoparasitism, carrion and predation
This category is very broad and refers to other strategies used by aquatic birds that live in the marine environment, which are part of the next trophic level. Kleptoparasites are seabirds that normally feed on the food of other birds. This is mostly the case for frigatebirds and skuas, which use this feeding technique, although gulls, terns and other species are also capable of stealing food opportunistically.
The habit that some species of birds have of nesting at night has been interpreted as a way to avoid the pressure exerted on them by this aerial piracy. Typically, this kind of behavior becomes common around nestling time, when parents bring food to the nests and are intercepted by young adults, who are faster and more aggressive than older birds.
Moreover, it has been proven that kleptoparasites can choose their victims very well. However, kleptoparasitism does not play a preponderant role in the diet of any bird species, what it is is a nutritional supplement obtained through hunting. A study carried out on how the common frigatebird is dedicated to stealing food from the masked gannet, concluded that the former was able to obtain at best 40% of the food it needs, but on average it only obtained 5 %.
Many species of gulls feed on the carrion of birds or marine mammals whenever the opportunity presents itself, as do giant petrels. Several species of albatross are also carrion-eating birds, an analysis of albatross beaks has revealed that many of the squid they ate are too large to have been caught alive and that has included species that are from mid-water, which is beyond the reach of these birds.
It has been shown that some species also feed on other seabirds, such as gulls, skuas, and pelicans, which prey on eggs, chicks, and young adults from nesting colonies when given the opportunity. Similarly, giant petrels can take prey the size of little penguins and seal pups.
Waterfowl Life Cycle
The life of aquatic birds that live in the sea is different from the life of birds that have their habitat on land. In general, they are strategic beings, and they manage to live a longer period of time, which has been calculated between twenty and sixty years, but it is also true that their first mating does not occur until they are ten years old and they also invest a greater amount of time effort in fewer offspring.
Many of the species only have one spawn per year, unless by some accident they have lost the first spawn, with exceptions such as the sooty mongrel and many species, such as the procellariiforms or the sulids, are only capable of laying a egg per year.
Waterfowl that have a marine habitat take care of the young for a very long time, which can last up to six months, which is a very long period among birds. An example of this is that, once the guillemot chicks fledge, they will still stay with their parents in the sea for many months.
Frigatebirds are the birds that exhibit the most parental care, with the exception of a few birds of prey and the southern ground hornbill, which is a species in which the chicks obtain their feathers after four or six months and then remain in the care of their young. parents for another fourteen months.
Due to the extensive period of parental care of their young, the reproduction of these birds only occurs every two years, instead of being annual. This mode of life cycle possibly evolved as a result of the difficulties of marine life, especially what has to do with the hunting of prey that are widely dispersed, as well as the number of failures in reproduction due to the fact that there are unfavorable marine conditions and the relative lack of predators compared to land-dwelling birds.
Thanks to the fact that they spend a greater amount of effort in being able to raise the young and because finding food generally forces them to move far from their nest site, in all marine species, except phalaropes, both parents they have to take part in the care of the chicks and the couples are monogamous, at least for a season.
Many species, such as gulls, alcids and penguins, are capable of keeping the same mate for many seasons, and many species of petrels are partners for life. Albatrosses and procellarids, which mate for life, need several years of courtship to be able to establish a pair bond before having offspring, in the case of albatrosses, there is a very elaborate courtship dance that is part of the formation of this link.
Nesting and Colony Formation
95% of marine waterfowl form colonies, which are among the largest bird settlements in the world. Colonies of more than a million birds have been documented, both in the tropics, as occurs in Kiritimati in the Pacific, and in polar latitudes, as is the case in Antarctica. These large groups serve almost exclusively for nesting. When they are not in the mating season, non-breeding birds settle in areas where there is the greatest amount of prey.
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The way the colonies are placed is very changeable. It is possible to achieve individual nests distributed with enough space between them, as occurs in an albatross colony, or concentrated, as occurs with a guillemot colony. In most of these colonies several species can nest, although they are visibly separated by some kind of niche differentiation.
Waterfowl living in the sea may nest in trees, if they are found there, but also in plants, sometimes building their nests on top of them, cliffs, underground burrows and rocky crevices. In this aspect, it has been possible to observe a strong territorial behavior of seabirds of the same or a different species. In fact there are aggressive birds like sooty terns that drive less dominant species out of more desirable nesting spaces.
In the winter time, the petrel avoids competing with the more aggressive Pacific shearwater for nesting grounds. Should mating seasons overlap, Pacific shearwaters may kill young petrels in order to use their burrows.
They are faithful to the place where they were born, in the same way they use the same hiding place or place of settlement for many years, proceeding to aggressively defend what they consider their territory from those they consider their rivals. This has increased their popularity. reproductive success, providing a place for pairs to congregate and minimizing the effort of searching for a new nest site.
However, finding a nesting site may have good results in the case of mating, if the new ground proves productive. Young adults mating for the first time usually return to their natal colony and nest near where they were born. This custom, known as philopatry, is so strong that a study of Laysan albatrosses found that the average distance between the bird's hatching site and the bird's own nesting site It was 22 meters.
Another study, but carried out with Cory's shearwaters that nest near the island of Corsica, revealed that nine out of 61 young males returned to mate to their natal colony and nested in the hiding place in which they grew up, two even managed to mate with their own mother . Philopatry appears to promote mating success and influence mate choice in the case of the Cape gannet and the Australian gannet.
The colonies of these birds are usually located on islands, cliffs or headlands, in areas where mammals have difficult access. This probably offers additional protection to these birds, which are usually found unprotected on land. The formation of colonies appears in families of birds that do not defend their feeding areas, as is the case of swiftlet, which have a food source that is very changeable and it may be that this is the reason why it appears more frequently in aquatic birds that live in the sea.
Another possible benefit of living in colonies is that they can function as information centers, in which seabirds, which take flight to feed in the sea, are able to know what kind of prey is available. , just by observing the other birds that inhabit the colony when they return.
On the other hand, there are also disadvantages, as living in a colony means that diseases can spread very quickly. Another is that colonies often draw the attention of predators, particularly other birds. Many species of colonial birds have been forced to return to their nests at night to avoid predation.
Immigration
An example of aquatic birds that have their habitat in the sea and that migrate are the pelicans that arrive every year in Cuba from North America during the winter season in the northern hemisphere. In the same way that other species do, seabirds have a habit of migrating when the mating season is over.
Of all the birds that migrate, the journey made by the arctic tern is the longest, as this bird crosses the terrestrial equator to spend the austral summer in Antarctica. Other species also make trips that cross the equator, both from the sir to the north and in the opposite direction. The population of elegant terns that have their nests in Baja California separates after the mating period into groups that travel north to the central coast of California, while others travel south to Peru and Chile to establish themselves in the current area. of Humboldt.
Sooty Shearwaters also make an annual migration cycle that rivals that of Arctic Terns. These are birds that make their nests in New Zealand and Chile and during the boreal summer they migrate to the North Pacific coast, in places like Japan, Alaska and California, making an annual journey of 64 kilometers.
Other waterfowl species migrate shorter distances from nesting sites and their distribution in the high seas is determined by the availability of food. In the event that the ocean conditions are not adequate, marine waterfowl migrate to areas where there are better conditions, becoming a permanent destination if it is a bird that is very young.
After fledging, young birds tend to disperse more than adults and in different areas, so it is not uncommon for them to be observed outside the normal geographic distribution of the species. Some of them, like the alcids, do not have an organized migration, but the group is capable of heading south when the winter season comes. However, other species of birds do not disperse, as occurs in some hydrobatids, pelecanoids and phalacrocoracids, but stay close to the area of their nesting colonies throughout the year.
out of the sea
Although the definition of this group of birds gives the idea that they spend their lives in the ocean, many species of seabirds throughout their lives come to reside to a lesser or greater extent in areas located inland. Multiple species breed tens, hundreds or even thousands of kilometers away from the coast. Some of these species return to the ocean to feed; as an example of this, nests of snow petrels have been found located 480 km inside the Antarctic continent, although it is unlikely that it is a place where they can find something to eat near those places.
The marbled murrelet nests in primary forests and looks for large conifers and many branches to build its nest there. Other species, such as the Californian gull, make their nests and feed in lakes, although later they go to the coasts. in winter. Some species of phalacrocoracids, pelicans, gulls and terns never go to sea, but stay in lakes, rivers and swamps; some gulls stay in cities and farmland. In these cases, they are said to be terrestrial or freshwater birds that have marine ancestors.
Some marine waterfowl, in particular those that nest in the tundra, such as the stercorarids and the phalaropes, also migrate over land. Other species, such as petrels, razorbills and gannets, have more limited habits, but occasionally stray from the sea as vagrants. This often occurs in inexperienced young birds, but it also occurs in many exhausted adults passing through heavy storms, which is known as a wreck, which literally means shipwreck. which bird watchers make many sightings.
Relations with the human being
Since time immemorial, this kind of birds have maintained a relationship with human beings, so we are going to analyze several aspects of them:
seabirds and fishing
Waterfowl that live in the ocean have a long association with fishing and sailors, from which benefits and disadvantages have been derived. Traditionally, fishermen have used seabirds as signals of the presence of schools of fish, as well as ocean banks with potential fishing resources and possible places to land.
In fact, the association of marine waterfowl with the land that was essential to enable Polynesians to locate small islands in the Pacific is well recognized. Similarly, these birds have provided food to fishermen who have been far from the mainland, as well as bait. Even tied cormorants have been used to catch fish. Indirectly, the fishery has benefited from the guano produced by the bird colonies, since it is an excellent fertilizer for the surrounding beaches.
As for the negative effects produced by aquatic birds of the sea on fishing industries, they are mostly limited to looting that occurs in aquaculture plants. For their part, in longline fishing, these birds steal the baits. In fact, there are also reports of prey depletion due to seabirds, but, although there is some evidence of this, its effects are considered less than those produced by marine mammals and predatory fish, such as tuna.
Several species of ocean waterfowl have benefited from fisheries, particularly discarded fish and offal. An example of this is that the latter are 30% of the diet of these birds in the North Sea and up to 70% of the food in other populations of seabirds. These kinds of activities can have other effects, such as the case of the proliferation of the boreal fulmar within the British territory, which has been attributed in part to the availability of this class of discards.
Discards generally benefit birds that feed on the sea surface, such as gannets and petrels, but not birds that pursue food by diving, such as penguins. On the other hand, the fishing industries also produce negative effects on the waterfowl of the sea, especially on the albatross, which has a very long life and takes a long time to reach sexual maturity and manage to mate; this is a relevant concern for conservationists.
The case of accidental capture of birds that get caught in nets or hooked on fishing lines has had a very negative effect on the number of individuals in their populations; As an example of this, scholars estimate that 100 albatrosses get entangled and drown each year in the tuna lines that are placed by longline fishing activity.
But, in general terms, each year hundreds of thousands of birds have been captured and die, something that is very worrying when considering some of the rarest species, such as the short-tailed albatross, is that their population of has been reduced to only 2000 individuals. According to a study carried out by the National Program of On-Board Observers of the Uruguayan Tuna Fleet, the species that are most affected by this type of incident with longline fishing are the black-browed albatross, the fine-billed albatross and the the white-throated shearwater. Seabirds are also believed to suffer from the consequences of overfishing.
Exploitation
Another aspect that has contributed to the alarming decrease in the population of aquatic birds is the hunting of which they have been objects and the collection of their eggs, for human consumption, even this has caused the extinction of some species, among which there is the giant auk and the brilliant cormorant. These species of birds were hunted for their meat by coastal inhabitants for a very long time; Moreover, towards the south of Chile, some archaeological excavations that were carried out in middens showed that the hunting of albatrosses, cormorants and shearwaters was a common activity from about 5000 years ago.
That was the reason that several species became extinct in different places, especially about 20 of 29 species that used to do so no longer reproduce on Easter Island. During the XNUMXth century, the hunting of these birds for their fat and feathers to be sold in the market for hats reached industrial levels.
Muttonbirding, which was the collection of shearwater chicks, took place as a developed industry of great importance in New Zealand and Tasmania, and the case of the Solander's petrel, which is known in those areas as the providence petrel, was very famous for its arrival in miraculous appearance on Norfolk Island, in which a windfall for hungry European settlers took place.
In the case of the Falkland Islands, it is known that hundreds of thousands of penguins are captured annually for their oil. For a long time, the eggs of waterfowl that have their habitat in the sea have been an important source. of food for sailors who make long trips, and it has also been observed that their consumption has also increased at times when urban settlements have grown in areas close to a bird colony.
In the mid-XNUMXth century, San Francisco egg collectors were able to collect about half a million eggs a year on the Farallon Islands, a period in Farallon Island history from which the birds are still trying to recover. Unfortunately, both hunting and egg gathering are still carried out today, although not with the same intensity as in the past, and in general, it could be said that with greater control.
A particular case is that of the Maoris who inhabit Stewart Island, who continue to collect sooty shearwater chicks, in the same way it has been done through the centuries, with their traditional methods, which have received the name of kaitiakitanga. , to take care of the collection, although now they do it in collaboration with the University of Otago, to be able to study the bird populations. However, in Greenland, uncontrolled hunting still continues, which is leading several species to a long-term population decline.
Other threats
There are other human threats that have contributed to the decrease or direct extinction of populations, colonies and species of marine aquatic birds. Of these, the most serious has probably been the introduction of alien species. The waterfowl of the sea, which nest in particular on small isolated islands, have forgotten many of the defensive behaviors they used to employ against predators.
This is what has happened with wild cats, who have the ability to catch birds similar in size to albatrosses, and many introduced rodents, such as the Polynesian rat, who can steal eggs hidden in burrows. . Another drawback is represented by goats, cows, rabbits and other introduced herbivores who have managed to cause problems, especially when the species require vegetation to protect themselves or to shade their chicks.
But a big problem in the colonies has been created by human beings, who disturb their normal existence. Those who visit them, even well-intentioned tourists, are able to scare the adults from the nests, causing the eggs and chicks to be abandoned and left vulnerable to predators.
In other cases, it may happen that the nests are destroyed by visitors. Several studies that have been carried out in relation to the penguins of Argentine Patagonia and New Zealand have shown that tourism influences the living conditions of these birds. An investigation on the impact of natural tourism on the colonies of Ojigualdo penguins proved that the presence of human beings on the beaches has prevented adults from finding the amount of food required for their chicks, which has a great effect on body mass and their chances of survival.
However, other research has suggested that the case of the Magellanic penguin, which also lives in Patagonia, is very unique because it does not leave its nest in the presence of humans, which has led to the conclusion that it is possible that the reproduction of this species is made to coincide with controlled ecological tourism.
But the big problem is pollution, which has caused a significant reduction in some species. The degree to which the environment is affected by some toxins and pollutants is also a cause for serious concern. Marine waterfowl were victims of DDT until, fortunately, the use of that chemical was prohibited due to the damage it causes to the environment; Moreover, its effects on the western gull had the effect that most of the new births were female, but also caused malformations in the development of the embryo and difficulty in reproduction.
In the 90s, this substance affected the Magellanic penguin and the Kelp Gull in the Argentine Sea. Marine waterfowl have also been affected by oil spills, because this substance destroys the impermeability of their plumage. , which causes these birds to drown or even die due to hypothermia. Another type of pollution that also affects them is light, which has a detrimental effect on some species, particularly aquatic birds of the sea. that have nocturnal habits, as is the case of petrels.
Conservation
The protection of marine waterfowl is a practice that can be considered ancient, because in the XNUMXth century, Cuthbert of Lindisfarne had already succeeded in enacting what is now considered the first law for the conservation of birds in the Farne Islands. Although many Species had disappeared by the XNUMXth century, such as the giant auk, Pallas's cormorant or the Labrador duck.
At the end of that century, the first laws aimed at protecting birds came into force, as well as hunting regulations that directly prohibited the use of lead shot, for having poisoned many birds.
Lead poisoning in waterfowl is the cause of severe anemia and disorders of the circulatory, immune, and nervous systems, as well as disorders of the liver, kidneys, and fertility. This kind of poisoning can lead a bird to death in a few days or weeks, but another inconvenience they generate is that they produce negative effects on the ability of birds to make their migrations.
In the United States, the risks that threaten the existence of marine waterfowl are not unknown to scientists who are part of the conservation movement. In 1903, President Theodore Roosevelt declared that Pelican Island, Florida, should be considered a national wildlife refuge, with the aim of protecting bird colonies, particularly the brown pelican that nests in her.
In 1909 the same president issued a declaration that protected the Farallón Islands. Today, many colonies enjoy protective measures, such as those that gather on Heron Island in Australia or on Triangle Island in British Columbia. Another initiative is the techniques that have been used for ecological restoration, in which New Zealand has been the pioneer, have allowed the removal of invasive alien species from these islands, which are getting bigger and bigger.
In fact, feral cats have been expelled from Ascension Island, as have polar foxes from the Aleutian Islands and rats from Campbell Island. The removal of these introduced species has allowed their numbers to increase. of specimens of the species that were under pressure from these predators, and even the return of species that had been expatriated have returned. After the cats were driven off Ascension Island, seabirds returned to nest there for the first time in over a hundred years.
The investigations of the colonies of marine aquatic birds will allow their conservation possibilities to be improved and to protect the areas they use for their reproduction. In the case of the European shag, which lives in the Western Palearctic, its migrations are determined by its fidelity to a place. A study on the colony of the Cíes Islands in Spain has concluded that, since reproduction has been more successful when these birds conquer new places, then the protection criteria should not only be based on the number or size of the populations. , but must take into account the etiology of the species.
In the case of the Kelp Gull, which nests along the Argentine coast and Patagonia, it is also thought that it is necessary to design conservation programs that take their mating habits into consideration. In addition, certain seabirds can act as sentinel species. , that is, that its health and conservation status serves as the indicator of the rest of the bird populations. This is the case of the brown pelican in the islands of the Gulf of California, in Mexico.
The true state of conservation of seabirds in Spain was not studied and was ignored until the 80s, when data began to be collected and made available. Likewise, since 1954, when the Spanish Ornithological Society was created, it is considered that the situation of birds in the country has improved. In 2016, the O Grove Ornithological Reserve was created in Pontevedra, Galicia, which was the first in that region and that has marine territories, and in it you can see species such as the Balearic shearwater and the European cormorant.
At the same time, in Latin America, there are also initiatives that aim to protect marine fauna and aquatic birds, such as the research carried out in the Gorgona Island nature reserve in Colombia, or the numerous protected areas in the province of Buenos Aires. , in Argentina. But today it is insisted that in order to guarantee the conservation of marine aquatic birds it is necessary to consider their ethology and their mating cycles.
One of the initiatives that should be promoted is the one that seeks to reduce the mortality of waterfowl that have their habitat in the sea due to longline fishing that uses techniques such as using fishing lines at night, or that dye the hooks of color blue or that place it underwater, such as increasing the weight of its lines or using scarecrows. Today, more and more international fishing fleets have been forced to use such techniques.
The international ban on fishing with gillnets has reduced the number of birds and other marine animals. Although, in any case, the nets that remain adrift, which is usually the product of an accident that is a consequence of this type of illegal fishing, continue to be a serious problem for marine fauna.
One of the Millennium projects, which turns out to be a preliminary step towards achieving the Millennium Development Goals, carried out in the United Kingdom by the Scottish Seabird Centre, which is located near the large bird sanctuaries in Bass Rock, in Fidra and in the surrounding islands. This area is the habitat of huge colonies of gannets, auks, stercorariids and other species.
This center makes it possible for visitors to watch live video from the islands and learn about the threats these birds are under and how best to protect them; In addition, the image that this country has regarding bird conservation has been improved. The tourism that focuses on the observation of the acuatic birds marine generates income to the communities of the coast and gives greater impetus and knowledge about their care. Such is the case with the northern royal albatross colony at Taiaroa Head in New Zealand, which attracts XNUMX tourists a year.
As for the measures to protect these birds towards the end of the XNUMXth century, this has been accompanied by the protection of their habitats, particularly with regard to the conservation or recovery management of lagoons, estuaries, marshes, wintering or rest, as well as the protection of their food resources, by means of a regulation of the state of the species for hunting and that are not the object of scientific study.
Among the international agreements and conventions that have been reached is the Agreement on the Conservation of Albatrosses and Petrels, which has been ratified by Argentina, Australia, Brazil, Chile, Ecuador, Spain, France, Norway, New Zealand, Peru, the United Kingdom Kingdom, South Africa and Uruguay, the Berne Convention and the AEWA.
In popular culture
It is true that many species of marine aquatic birds have been little studied and that few things are known about them. However, some, such as albatrosses and seagulls, have not only been extensively studied, but have been close to human populations, which is why they have reached popular consciousness. Albatrosses have been described as the most legendary birds and are associated with a variety of myths and legends.
In the first place, the scientific name of the family to which albatrosses belong, Diomedeidae, is found in the myth of the defeat of the Argive hero Diomedes and his metamorphosis into a bird. Another example is the superstition of sailors, as they consider it bad luck to harm them. It is a myth that has its origin in the poem by Samuel Taylor Coleridge, The Rime of the Ancient Mariner, in which a sailor is condemned to carry the corpse of the albatross that he killed on his neck.
The second poem of The Flowers of Evil by Charles Baudelaire is called precisely The Albatross (L'albatros), which is a composition in three quatrains and in Alexandrian verse; in that poem, the lyrical self describes the sailors' habit of hunting these birds and also the effect this has on them, first so majestic and then so clumsy. The poet compares himself to an albatross, because his giant wings prevent him from walking.
In popular music this bird also had importance. The 2014 electro house song I'm an Albatraoz, which had great commercial recognition and fame, is about the story of a woman who identifies with an albatross, as opposed to another, named Laurie, who is associated with a mouse.
Gulls are among the best-known waterfowl of the sea, due to their ability to use man-made habitats, such as cities and landfills, and their often intrepid character. Therefore, it is other birds that have their place in the popular consciousness. According to the myth of the indigenous Lilloet, the seagull is the one that guarded the light of day, until the raven stole it; which is very consistent with the general symbology of birds, which represent an impulse of elevation and spirituality.
We can also find them in literature in the form of a metaphor, as is the case of the book Juan Salvador Gaviota by Richard Bach, or to denote proximity to the sea, as its use in The Lord of the Rings by JRR Tolkien, both in the insignia of Gondor and, consequently, Númenor, which was used in the scenic decoration of the film adaptation, as in the song that Legolas sings in the forest of Ithilien, in which he reveals his longing for the land to which he will depart, the abode last of the elves
Another example can be found in the seagull by Anton Chekhov, about a failed actress who stars in the story, Nina, who observes an embalmed seagull and considers it a symbol that she does not quite understand; this object is a prolepsis of the suicide of her lover, the playwright Tréplev.
The seagull in this work can represent madness and freedom. Other species have also served as inspiration for humans, since pelicans have long been associated with mercy and altruism, due to an early Western Christian myth that indicates that these birds opened their chests to feed their young. hungry pigeons. In fact, it is an image that is an allegory of Christ.
Endangered marine waterfowl
Throughout the planet there are around three hundred species of aquatic birds that have their habitat in the sea, which make up some six hundred and thirty million individuals in total, of which there are one hundred and ten species that are threatened, and that are about sixty million. individuals, which have suffered a decrease of 70% since 1950. The most relevant threats have been habitat alteration, pollution, climate change and commercial fishing.
There are nine orders of seabirds:
- Fetontiformes, with three species known as tropicbirds;
- Pelecaniformes, with three species of pelicans, without threats;
- Podicipediformes, with four species of grebes and grebes, with one threatened, the red-necked grebe;
- Gaviforms, with five species of loons, divers, without threats;
- Sphenisciformes, with eighteen species of penguins, ten threatened species;
- Anseriformes, with one hundred and eighty species in three families, but only twenty-one species of seabirds, including ducks, serretas and eiders, of which four are threatened;
- Suliformes, with forty-five species of seabirds, including frigatebirds and cormorants, of which fifteen are threatened;
- Caradriiformes, with one hundred and twenty-one species, including seagulls, terns and puffins, of which sixteen are threatened; and
- Procellariforms with one hundred and forty species, including albatrosses, shearwaters, petrels, of which sixty-four are threatened.
freshwater wetland waterfowl
In this section of the article we are going to tell you about the waterfowl that live in wetland areas, which we usually find when we make vacation trips or weekends, and in which from time to time we cross through areas where there are accumulations of water. , whether they are lakes, salt flats, swamps, or others, in which it is normal for us to find a wooden observatory that people come to look at.
Once inside, people lean out and look at the landscape to observe a large number of birds and then return home, but it is not necessary to enter the wooden huts to observe these birds, because the humid areas are the places where you can find the largest number of bird species.
In a wetland, the most usual thing is that you can find dozens of species of aquatic birds, but there are some that, due to their commonness, you will almost always find them. What's more, they are usually so common that when you spend some time searching and observing birds, your brain will completely ignore them. This is what normally happens with the most common Anatidae (ducks), such as the mallard, the common teal, the common shoveler and the European pochard, and we take this opportunity to inform you that those commonly known as ducks in the vocabulary used in ornithology they are called Anatidae, because they belong to the Anatidae family.
The four common species of ducks that we have mentioned before as very common, have breeding and wintering populations in Spain, so you will be able to see them in all four seasons of the year, although it turns out that the teal and the spoon are a bit scarce in spring and summer and most likely you will not see them at those times. Another striking aspect of these birds is that they have a great sexual dimorphism, because the males, as with many birds, are the ones with striking colors, but at the same time that implies that it is up to them to do the courtship. .
The best known of all of them is probably the mallard (Anas platyrhynchos), which is also called the mallard. It is the typical duck that has a green neck and that can be found in all the gardens that have a pond, they can even swim in your pool if they want, but you will also be able to observe them in the field.
The common teal (Anas crecca), on the other hand, looks like a mini duck next to it, because they are smaller and more compact. The common shoveler (Anas clypeata) also has a green head but they have a very large beak, which is shaped like a spoon and is used to filter food from the water.
The European Pochard (Aythya ferina) is difficult to confuse due to its pointed head and deep brown cheeks or jaws, which will contrast with the black color of its chest and light body. The females and the young, on the other hand, are more discreet specimens, thanks to their mottled brown colors, which are a kind of camouflage, since they are in charge of protecting their offspring and have to go unnoticed.
So how to distinguish them?
The way wetland waterfowl look in general is different, but if it is the first time for a person to observe them, it is possible that they may think that they are all the same, but since we do not want you to fall into that mistake, let's go I'll show you a few tricks so you can identify one from the other:
- The female specimens of the mallard duck have the espejuelo, which is a blue spot on part of the secondary wing feathers.
- Female Teals resemble Teals, but have green specs and are more compact or smaller.
- Female shovelers have a green beak and a beak so peculiar that if you get confused when identifying them, it is because you are not paying due attention.
- The females of the common pochard are the most bland in the world in terms of colors. If you have the option of reading the descriptions in the bird guides, you will see that they are very brief, because they are full of adjectives of the grayish, pale, dull, gray-tinted type. They are birds shaped like a pochard but they are discolored.
Diving birds: Little Grebe and Great Crested Grebe
Although they look like ducks, they are not really, if we speak from a technical point of view. They belong to another family Podicipedidae. In fact, the beak and the hydrodynamic shape of the body that they have and that has been adapted to allow them to dive are the peculiarities that distinguish them. So it is not possible that you can confuse them:
The little grebe (Tachybaptus ruficollis) is the rubber duck of wetlands. It is very funny, it has a small body and it will continually dive into the water to dive. The Great Crested Grebe (Podiceps cristatus) is much larger, but that does not prevent it from also being an excellent diver. In winter, moreover, it can sometimes be seen in the sea. In summer it has one of the most striking plumages and courtships of all birds and they move their heads facing each other until they find a mate.
All people, when they see a bird with long legs in a wetland, usually call it a heron. But there are many herons, however not all birds that have long legs are. It is a common mistake to call a stork a heron, when in fact it is not.
Between the cattle egret (Bulbucus ibis) and the little egret (Egretta garzetta), the main difference that can be observed, although there are many others, is in the color of the beak, because in the former it is orange and robust, while which is black and narrow in the second, and the size is smaller in the case of the bueyera.
Cattle herds, who receive that name because they have the habit of climbing on top of the oxen in the savannah, in order to eat their parasites, you will also be able to find them feeding on the ground, even on the sides of the farm fields. In contrast, little egrets feed mainly on what they catch from the shore with their quick movements.
The gray heron (Ardea cinerea) is larger than the ones we have mentioned before and has gray and striated colors on the chest so they are unmistakable. The black-winged stilt (Himantopus himantopus) is the only one of the three that is not an ardeida (heron) that gets its name from its reasonable resemblance to the white stork, but the truth is that it is not related to it. It is a bird that has a very bad character when it comes to defending its nest.
Some extra resources
The Rails: The Coot (Fulica atra) and the Common Moorhen (Gallinula chloropus) are birds that have black plumage and are very common, but they are distinguished by the beak, which is white in the coot and red in the moorhen, in addition to the fact that the moorhen is a bird that looks more like a chicken, while the coot is a bird that looks more like a duck. In addition to all these species, in wetlands you may find many other species of birds, but in this post we have tried to focus on the birds that are typical of wetlands and that you will surely find in any of them.
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