---
title: "What the sources say about the Western Grebe | AnimalTracks.wiki"
description: "44 claims from the Western Grebe profile, each beside the words of the source that backs it."
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---

# What the sources say about the Western Grebe (*Aechmophorus occidentalis*)

> 44 claims from the Western Grebe profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Western Grebe](https://animaltracks.wiki/animals/western-grebe/)

## Aechmophorus occidentalis (western grebe). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Aechmophorus_occidentalis/

| The page says | The source says |
| :--- | :--- |
| Freshwater lakes and marshes with rushes and tules across western North America in summer | It lives on freshwater lakes that have rushes and tules during the breeding season. |
| A western grebe's red eye is surrounded by dark coloring and its bill is dull yellow or olive, while a Clark's grebe has white around the eye, a bright yellow to orange-yellow bill, whiter flanks, and a paler gray back. | The Western Grebe has a dull yellow or olive-colored bill and red eyes surrounded by dark coloration... 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. |
| breeding on freshwater lakes with rushes and tules | It lives on freshwater lakes that have rushes and tules during the breeding season. |

## Western Grebe. Audubon Field Guide to North American Birds.

https://www.audubon.org/field-guide/bird/western-grebe

| The page says | The source says |
| :--- | :--- |
| A neck structure, found among grebes only in it and Clark's grebe, for rapid spear-like thrusting of the bill | Western Grebe and Clark's Grebe are the only grebes having structure in neck allowing the rapid spear-like thrusting of bill |
| mostly sheltered coastal bays and estuaries on the Pacific coast in winter | Winters mainly on sheltered bays or estuaries on coast |
| Mostly fish, plus crustaceans, insects, worms, salamanders, and feathers | The Western Grebe apparently feeds mainly on fish at all seasons and in all habitats. Also known to eat crustaceans, insects, polychaete worms, salamanders. Like other grebes, also eats feathers. |
| During a courtship display called rushing, two or more birds rear upright and sprint side by side across the surface, feet pattering loudly, then dive underwater at the end of the run. | Most conspicuous is a display in which two (or more) birds rear up to upright posture and rush across surface of water side by side, with loud pattering of feet, diving underwater at end of rush (note: 'rear up to upright posture' is the source's own wording; the 'up to' there is idiomatic, not a quantity hedge) |
| An adult measures 53 to 74 centimeters (21 to 29 inches) long and weighs 0.8 to 1.6 kilograms (1 pound 12 ounces to 3 pounds 7 ounces), with males slightly larger. | Sexes similar; male slightly larger — Length: 21 in-2 ft 5 in (53-74 cm); wingspan: 2 ft 7 in-2 ft 11 in (79-90 cm); weight: 1 lb 12 oz-3 lb 7 oz (800-1.6 kg). (note: 21 to 29 inches restates the source's own '21 in-2 ft 5 in' (2 ft 5 in = 29 in); 0.8 to 1.6 kilograms restates its own '(800-1.6 kg)' (800 g = 0.8 kg)) |
| Western and Clark's grebes are the only grebes with a structure in the neck that thrusts the bill forward like a spear, which may help them spear fish, though how they use it isn't well known. | Western Grebe and Clark's Grebe are the only grebes having structure in neck allowing the rapid spear-like thrusting of bill; may be useful in spearing fish, but use of this behavior is not well known. |
| The species appears to feed mainly on fish, and is also known to eat crustaceans, insects, worms, salamanders and, like other grebes, feathers. | The Western Grebe apparently feeds mainly on fish at all seasons and in all habitats. Also known to eat crustaceans, insects, polychaete worms, salamanders. Like other grebes, also eats feathers. |
| A pair builds its nest as a floating heap of plant material anchored to standing marsh vegetation, in a colony. | Nest: Site is in shallow water marsh. Nest (built by both sexes) a floating heap of plant material, anchored to standing vegetation. (note: 'in a colony alongside other pairs' from the same page's Nesting line: 'Breeds in colonies.') |
| The female lays two to four pale bluish-white eggs, rarely as few as one or as many as six, and both parents incubate them for about 24 days. | A Western Grebe generally lays 2-4 eggs, rarely 1-6. The eggs are pale bluish white, becoming nest-stained brown. Incubation by both sexes, about 24 days. |
| Chicks climb onto a parent's back within minutes of hatching and soon leave the nest, and both parents feed them. | Climb onto back of parent within minutes after hatching, soon leave nest; are fed by both parents. |
| A bare patch of yellow skin on a chick's head flushes scarlet when it begs for food or gets separated | Patch of bare yellow skin on head of young turns scarlet when young beg for food or are separated from parents. |
| a young grebe takes its first flight at about 10 weeks old | Age at first flight about 10 weeks. |
| Around the start of the 20th century, tens of thousands of these grebes were killed for their feathers, and numbers appear to have recovered after that | Around beginning of 20th century, tens of thousands were killed for their feathers. Apparent recovery since, and has begun breeding in new areas not occupied historically. (note: 'after that' places Audubon's 'Apparent recovery since' after the plume trade, not after the 1975-2010 decline) |
| wintering mainly on sheltered coastal bays and estuaries | Winters mainly on sheltered bays or estuaries on coast |
| It hunts by diving and swimming underwater, driven mainly by its feet. | Forages by diving from surface and swimming underwater, propelled mainly by feet. |
| Two or more birds rear up side by side and run across the surface with a loud pattering of feet | two (or more) birds rear up to upright posture and rush across surface of water side by side, with loud pattering of feet (note: settle #889 (vibe.reason)) |

## Aechmophorus occidentalis. AnAge: The Animal Ageing and Longevity Database.

https://genomics.senescence.info/species/entry.php?species=Aechmophorus_occidentalis

| The page says | The source says |
| :--- | :--- |
| A wild western grebe has been recorded living to 14 years old. | Maximum longevity 14 years (wild) |
| weightKg: 1.48 | Adult weight 1476 g (note: settle #889; Audubon 800 g to 1.6 kg, all Light class) |

## Western Grebe (Aechmophorus occidentalis), version 1.0. Birds of the World, Cornell Lab of Ornithology.

https://neotropical.birds.cornell.edu/Species-Account/nb/species/wesgre

| The page says | The source says |
| :--- | :--- |
| Western grebes range from southern Canada to the Mexican Plateau | The Western Grebe is a conspicuous waterbird of western North America that ranges from southern Canada to the Mexican Plateau. |
| Western and Clark's grebes were treated as color phases of one species, the western grebe, from 1886 until 1985. | Because Western Grebe and Clark's Grebe were from 1886 until 1985 considered color phases of the Western Grebe |
| The case for splitting them began with the finding that each mates mostly with its own kind, and a DNA study found them about as distinct as other species in the same genus. | Evidence for the renewed specific status of Western Grebe began with finding that Western and Clark's grebes mated assortatively |
| a DNA study found them about as distinct as other species in the same genus | indicated that the median DNA sequence distance between the species was comparable to such distances between other congeners |

## Clifton, Hedrick & Biewener (2015). Western and Clark's grebes use novel strategies for running on water. Journal of Experimental Biology.

https://doi.org/10.1242/jeb.118745

| The page says | The source says |
| :--- | :--- |
| Western grebes do something few vertebrates can: they run upright across open water. | Few vertebrates run on water. The largest animals to accomplish this feat are western and Clark's grebes (Aechmophorus occidentalis and Aechmophorus clarkii). |
| Tied with Clark's grebe as the largest animal known to run on water, sprinting across a lake in a courtship display called rushing. | The largest animals to accomplish this feat are western and Clark's grebes (Aechmophorus occidentalis and Aechmophorus clarkii). These birds use water running to secure a mate during a display called rushing. |
| A 2015 study filmed them with high-speed video | High-speed video recordings elucidate the hindlimb movements of grebes rushing in the wild. (note: 2015 is the paper's publication year (Journal of Experimental Biology 218, 2015)) |
| Western grebes and their close relative, Clark's grebe, are the largest animals known to run on water. | The largest animals to accomplish this feat are western and Clark's grebes (Aechmophorus occidentalis and Aechmophorus clarkii). |
| a rushing grebe's feet hit the surface at stride rates reaching 10 Hz | rushing grebes use exceptionally high stride rates, reaching 10 Hz |
| that slapping alone supplies up to 30 to 55 percent of the lift the bird needs to keep from sinking | grebe foot size and high water impact speed allow grebes to generate up to 30-55% of the required weight support through water slap alone |
| Flattened bones in its foot cut drag, letting it pull each foot sideways out of the water. | flattened foot bones reduce downward drag, permitting grebes to retract each foot from the water laterally |
| Roughly Ten Times Heavier Than a Basilisk | Grebes weigh an order of magnitude more than the next largest water runners, basilisk lizards (Basilicus basiliscus) (note: 'roughly ten times' is a plain-language rendering of 'an order of magnitude'; 'heavier' restates 'weigh ... more') |
| A grebe outweighs it by about an order of magnitude, so it faces a greater challenge holding up its own weight. | Grebes weigh an order of magnitude more than the next largest water runners, basilisk lizards (Basilicus basiliscus), and therefore face a greater challenge to support their body weight. (note: 'so' restates the source's own 'and therefore') |
| In a 2015 study, researchers filmed rushing grebes in the wild with high-speed cameras and ran lab experiments with physical models and a preserved grebe foot, to estimate how much of the bird's weight slapping the water holds up. | High-speed video recordings elucidate the hindlimb movements of grebes rushing in the wild. We complement these findings with laboratory experiments using physical models and a preserved grebe foot to estimate how slapping the water surface contributes to weight support. (note: the year 2015 is the paper's own publication year, quoted separately in the 'A 2015 study' claim above) |
| The basilisk lizard is the next-largest animal known to run on water. | Grebes weigh an order of magnitude more than the next largest water runners, basilisk lizards (Basilicus basiliscus) |
| at stride rates reaching 10 strides a second | rushing grebes use exceptionally high stride rates, reaching 10 Hz (note: settle #889 (vibe.reason)) |

## Wilson et al. (2013). Citizen Science Reveals an Extensive Shift in the Winter Distribution of Migratory Western Grebes. PLoS ONE.

https://doi.org/10.1371/journal.pone.0065408

| The page says | The source says |
| :--- | :--- |
| A study of 36 years of Christmas Bird Count data | We used hierarchical modeling with a Bayesian framework applied to 36 years of Audubon Christmas Bird Count data to assess continent-wide and regional population trends in western and Clark’s grebes ( A. clarkii ) from 1975 to 2010. |
| the wintering population of the two species fell by roughly 52 percent after 1975 | the North American wintering population of Aechmophorus grebes decreased by ∼52% after 1975 |
| crashing by about 95 percent in the Salish Sea while growing by more than 300 percent along the California coast | Abundance decreased by about 95% over 36 years in the Salish Sea but increased by over 300% along coastal California. (note: the study's main analysis estimated trends for Aechmophorus spp. (both species), which the sentence's subject 'the wintering population of the two species' keeps) |
| moving the wintering range's center about 895 kilometers south between 1980 and 2010 | the mean centre of the species distribution shifted south by an estimated 895 km between 1980 and 2010 |
| Since the mid-1980s, the Pacific sardine stock off California grew from a few thousand metric tons to more than two million, while both the abundance and availability of Pacific herring declined in the Salish Sea. | Since the mid-1980s, the Pacific sardine stock off the California coast increased from a few thousand metric tonnes to over two million. At the same time both the abundance and availability of Pacific herring declined in the Salish Sea. |
| The 2013 study that measured the shift suspects a change in the forage fish they eat, and says the idea still needs testing. | Mechanisms underlying this shift require further study but we hypothesize that it may be related to a change in the abundance and availability of their forage fish prey base. (note: 2013 is the paper's publication year (PLoS ONE 2013); 'suspects' and 'the idea still needs testing' carry the source's 'hypothesize ... may be related' and 'require further study') |

## Aechmophorus occidentalis. The IUCN Red List of Threatened Species 2019: e.T22696631A139355294.

https://doi.org/10.2305/iucn.uk.2019-3.rlts.t22696631a139355294.en

| The page says | The source says |
| :--- | :--- |
| the IUCN rates the species Least Concern | IUCN Red List category: Least Concern (LC). |