Perception Channels: visual ; tactile ; acoustic ; chemical
Aechemophorus occidentalis is not endangered or threatened. They are however are affected by oil spills and insecticides found in their food. The insecticides affect their breeding. Another danger to this bird is the reduction in habitat. Lakes and marshes that A. occidentalis occupies are being taken over by human development. At this time A. occidentalis hasn't been affected very much by these threats.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
There were no negative influences found.
Aechmophorus occidentalis is of economic interest to tourists, scientists, and developers. Tourists regularly go to wildlife refuges and preserves to go birdwatching. This brings entrance fees to the wildlife parks and refuges. Scientists are interested in A. occidentalis because its habitat (the wetlands) is being taken over by development. The fact that they are still thriving shows the condition of the environment.
Aechmophorus occidentalis is a carnivore. It mostly eats fish, but also eats insects, mollusks, and crustaceans. The Western grebe is an aggressive hunter. It dives under the water and spears fish with its long bill.
Aechmophorus occidentalis is commonly found from Canada through California, and sometimes in Mexico. It usually occurs in the great plains and western states, but occasionally can be found in the eastern half of the United States.
Biogeographic Regions: nearctic (Native )
Aechmophorus occidentalis is a migratory bird. It lives on freshwater lakes that have rushes and tules during the breeding season. It usualy stays on prairie lakes in British Columbia and California, and sometimes as far down as Mexico. In the winter A. occidentalis lives on the Pacific coast.
Aquatic Biomes: lakes and ponds; coastal
Range lifespan
Status: wild: 14 (high) years.
Average lifespan
Status: wild: 132 months.
Aechmophorus occidentalis is the largest of the North American grebes, it ranges from 56-74 cm in length. It has a long neck and bill. The feet are at the far back of the body and the tail is reduced. The ankle and toe joints are very flexible to aid in manueverability in the water. The head, neck, and body are a blackish brown color from above, and white from below. The Western Grebe has a dull yellow or olive-colored bill and red eyes surrounded by dark coloration. In flight a white wing stripe is exposed. The sexes are monomorphic year round.
Aechmophorus clarkii, Clark's grebe, was only recently recognized as a separate species. Clark's grebes have white surrounding the eye and a bill that is bright yellow to orange-yellow. Their flanks have more white areas and the back is a lighter gray.
Average mass: 1400 g.
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 1475.5 g.
Aechmophorus occidentalis breeds in the spring. It has a very elaborate courtship behavior. The couple will dance, posture, and run across the water. Many grebes ussually mate at the same time. The female lays three to five bluish white colored eggs. The nest floats on the water in the reeds. Both sexes take care of the young. They become very territorial during nesting. To avoid other nesting pairs the parents dive from the nest and swim underwater to go to feeding grounds.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Average time to hatching: 23 days.
Average eggs per season: 3.
The Western grebe (Aechmophorus occidentalis) is in the Podicipediformes order and Podicipedidae family. It lives throughout western North America, with its breeding grounds in the north-central and north-western regions of the United States and south-central Canada. It inhabits areas with freshwater lakes and marshes during the breeding season, and in the winter moves toward the coast (All About Birds 2018).
Adults have a black back and head, with this color extending to just below their red eyes. Their long neck is white except for a black band along the back, and their long, thin bill is dull yellow. They have a 31 to 34-inch (79-86 cm) wingspan and weigh between 28.2 and 63.5 ounces. Male and female Western grebes are similar in appearance and size, being 21.6 to 29.5 inches (55-75 cm) in length. Juveniles have shorter dark beaks and have a lighter gray coloring where the adults are black (All About Birds 2018; LaPorte et al. 2013).
These birds spend almost all their time in the water and are not well adapted for walking on land because of the far back position of their legs. They are excellent swimmers and divers, however, and even their courtship takes place in the water with a unique display called the “Rushing Ceremony” that involves running on the water with their necks jutting forward in a graceful fashion. They are very social, nesting in colonies and spending their winters in large flocks (All About Birds 2018; LaPorte et al. 2013; Seattle Audubon 2018).
The Western grebe’s main food source year-round is fish, and they dive underwater propelled by their feet and use their long necks and sharp bills like spears to thrust forward and stab their prey. Crustaceans, insects, polychaete worms, and salamanders are also part of their diet (Kaufmann 2018; Seattle Audubon 2018).
Both males and females build the nest out of plant material in a shallow marsh area on the water. The female lays 2-4 eggs, which are incubated by both partners for about 24 days. The eggs are a pale bluish-white that is often stained brownish due to the nest material. The hatching is not synchronized, and the last egg to hatch may be left behind. The young leave their nest within minutes of hatching and climb onto their parents’ backs, both of which help with feeding. If a hatchling gets separated from its parents, or if it begs for food, a patch of skin on its forehead, which is usually yellow, will turn scarlet. They are limited to one brood per year (All About Birds 2018; Kaufmann 2018).
In the early 1900s, many thousands of these birds were hunted for their silky feathers. Since then, the species was able to recover. The Western grebe population in North America is estimated to be more than 110,000 breeding birds. Although the population is declining, Mexican populations especially, the Western grebe is listed as a species of “least concern” on the IUCN Red List (Bird Life International 2016). These birds are sensitive to pesticides, oil spills, and other forms of low water quality, as well as sometimes becoming entangled in fishing lines and nets. If their nests are left vulnerable, gulls and other predators can feed on the eggs. Other reasons for their decline include the destruction of their nests due to the intrusion of boats, and a decrease of nesting habitat when plants surrounding the marshes are cut down (All About Birds 2018; Kaufman 2018; Seattle Audubon 2018).
The western grebe[2] (Aechmophorus occidentalis)[3] is a species in the grebe family of water birds. Folk names include "dabchick", "swan grebe" and "swan-necked grebe".
Western grebe fossils from the Late Pleistocene of southwest North America were described as a distinct species,[4] but later ranked as a paleosubspecies Aechmophorus occidentalis lucasi.[5] More recent study found them to fall within the variation now known to exist in today's birds.[6][7]
The western grebe is the largest North American grebe. It is 55–75 cm (22–30 in) long, weighs 795–2,000 g (1.753–4.409 lb) and measures 79–102 cm (31–40 in) across the wings.[8][9][10] It is black-and-white, with a long, slender, swan-like neck and red eyes. It is easily confused with Clark's grebe, which shares similar features, body size, behavior and habitat, and hybrids are known. Western grebes nest in colonies on lakes that are mixed with marsh vegetation and open water. Western Grebe nests are made of plant debris and sodden materials, and the nest-building begins roughly around late April through June. The construction is done by both sexes and is continued on throughout laying and incubation.[11] This species of waterbirds is widespread in western North America, so there is no specific place of abundance. Its subspecies, Clark's grebe generally populate more of the southern part of North America [12] Other differences are whiter flanks and paler gray backs when comparing A.o.clarkii to A.o.occidentalis.[13] The western grebe has black around the eyes and a straight greenish-yellow bill whereas the Clark's grebe has white around the eyes and an up-turned bright yellow bill. The downy young of Western are grey; Clark's downy young are white.
Out of the water
Swimming
In 1858 George Newbold Lawrence recognised Podiceps occidentalis based on darker coloured specimens, and P. clarkii based on three paler coloured specimens -two from California and one from Chihuahua. These two colour morphs were found to occur, roost and even interbreed together, and were long regarded to be synonyms (although it is unclear why P. clarkii was regarded as the junior synonym, coming alphabetically first). Deignan designated the Mexican specimen as the holotype of the taxon P. clarkii in 1961. In 1963 Dickerman reinstated the taxon as Aechmophorus clarkii, which he defined as the smaller birds, both dark and pale coloured, from Mexico. In 1979 a comprehensive study by Ratti demonstrated the apparent existence of reproductive barriers between different phases of the grebes. In 1986 Dickerman recognised the taxonomic significance of the distinctions between the dark and pale phase, and classified these phases as different subspecies:[14][15]
Multiple lines of evidence suggest that the differently colored western grebes (darker and lighter) are different taxa -in a single population in which sympatric speciation somehow persists. These forms were reported to mate according to their own colors and the mixing between dark and light-faced individuals is rare.[13] This type of assortative mating derives from possible isolating mechanisms such as differential responses to advertising calls and spatial distribution.[13][16] Each of the forms tended to stay closer to their own type, thus making their colony nesting be non-randomly distributed.[13]
By 1992 Storer & Nuechterlein were promoting another concept to the taxon A. clarkii, now regarding the pale morphs from the US and Canada to be this taxon (Dickerman's A. occidentalis ssp. ephemeralis).[17]
Western grebes nest in colonies of hundreds on large inland lakes, sometimes using coastal marshes, in western North America. It has a spectacular courtship display; two birds will rear up and patter across the water's surface. Northern birds migrate west to coastal ocean in winter; birds in the southwest and Mexico may be permanent residents. During the breeding season, the birds advertise themselves through ceremonies. Rushing Ceremony, which can be also called as water dance, race or run, is a ceremony that is the most frequent display to form a pair-bond. This is performed in pairs of either both male Western grebes or one male and one female. One of two individuals initiates Rushing, and the paired individual follows immediately and performs in synchrony. The birds lift their wings stiffly to the side and run in an upright position with its head held forward and neck curved. The males seem to perform the rushing together to attract the attention of females, and when one of two males attracts a female from his rushing behavior, a competition arises between males to get the female. One out of two withdraw and the "winning" male mates with the female by performing Rushing together and continue to perform Weed Ceremony.[18] Weed Ceremony usually precedes the acts of mating and nest building. It is done after the pair is formed, and the ceremony begins as the mates bob their heads in water. Then they dive in place and come back up to surface while holding weed on their beaks. This ceremony is continued until one of the pair flips away its weeds and drops to a normal position in water. They continue their mating with Greeting Ceremony. Greeting ceremony is similar to the form of rushing ceremony and involves dip-shaking, bob-shaking, bob-preening and arch-clucking.[19] Dip-shaking consists of dipping the head in the water and raising it up while rapidly waggling the bill side to side. This involves a low neck posture and conspicuous water splash while bob-shaking does not.[18] These breeding dances are known to be the most elaborated dances in the waterbird species.[19] After the breeding, the male Western Grebes feed their mate, thus performing mate feeding behavior. The feeding resembles the feeding of the young by parents, and through the feeding they obtain, females are able to have enough energy to form their eggs. During the incubation period, male and female Western Grebes trade places to incubate their eggs for weeks, and those that are not incubating feed their mate.[20]
When tending their young, Western grebe parents use different types of vocalization to communicate. Ticking is one of the two and is used as an alarm signal. Parents carry their newly hatched young on their backs, and when the parents make a ticking sound, this is used as a signal for their chicks to hide their heads beneath the back of their parents and be silent. If chicks are greater than 4 weeks of age, they respond to the ticking by swimming or diving away on their own. When making a ticking sound, the callers do not open their mouths, so it is hard to distinguish who is the maker of the sound. The parent who carries the chicks tend to make the ticking sound more often than those that do not, and both of male and female parents are equally likely to tick. Another vocalization noise is clucking, and this signals for food. When a parent clucks, the young respond to it by poking their head out of their parent back where they are on to receive food.[21]
The clutch size decreases as the mating season progresses, meaning if the mating is done at the last of days in mating season, the number of offspring produced is smaller.[22] However it is also stated brood size of nests that hatched later in the season is larger than those from earlier, which contradicts previous findings.[22] This may be due to ecological constraints. Ecological constraints also pressure the young, and this may lead to siblicide in the first weeks after hatching, which may explain the brooding differences.[22] Also, Western grebes are sensitive to humans, such that when there is human disturbance near them, the parents leave their nest, leaving their unhatched eggs vulnerable to attacks by predators. This shows the predation or even the seemingly threatening acts result in a decrease of reproduction and survival of the young.[23] Because they are so sensitive, there have been restoration efforts to rebuild the Western grebes' native habitats, so that they have greater opportunity to reproduce and raise their young without disturbance or threat. The number of Grebes has been slowly declining in the last two decades, not only because of predation, but also because of habitat destruction, with oil spillage being one of the major causes.[24]
This bird dives for carp, herring, mollusks, crabs, and amphibians, such as salamanders. It often peers below the water before diving. Recent observations suggest that the grebe dives at the bottom of the lake. Some smaller fish are impaled much like herons, with the bill, but others are grasped. Most are swallowed underwater, but some are brought to the surface, pinched, and swallowed.[25]
The western grebe (Aechmophorus occidentalis) is a species in the grebe family of water birds. Folk names include "dabchick", "swan grebe" and "swan-necked grebe".
Western grebe fossils from the Late Pleistocene of southwest North America were described as a distinct species, but later ranked as a paleosubspecies Aechmophorus occidentalis lucasi. More recent study found them to fall within the variation now known to exist in today's birds.
