Rosss Goose (Chen rossii) – Planet of Birds

Rosss Goose

Subspecies

Genus	Species	subspecies	Region	Range
Chen	rossii		NA	n

Genus

The white geese are a small group of waterfowl which are united in the genus or subgenus Chen, in the true geese and swan subfamily Anserinae. They breed on subarctic areas of North America and around the Bering Strait, migrating south in winter. Many authorities place these species in the grey goose genus Anser. Indeed, Chen and Anser are anatomically indistinguishable. However, external morphology, biogeography, and molecular data suggest that the white geese are indeed an evolutionary lineage distinct from the grey geese ? from which they split off fairly recently, essentially replacing them in North America. The AOU recognizes this genus as distinct; most other authorities today consider it a subgenus of Anser. Like grey but unlike the Branta black geese, their feet and legs are colored in reddish hues. The bill is also reddish in these birds as in most grey geese, except in adult males of Ross’s Goose which have a blue-black grainy cere. The wingtips are black, as in all true geese, whereas the head is always white without any markings or pattern in adult birds of this genus, which distinguishes them from all other true geese except feral domesticated geese. The rest of the plumage is either white all over, or colored in various dark bluish-grey hues; the latter birds, uniquely among true geese, do not have white uppertail and undertail coverts, though the tail itself may be white. White-phase snow geese of both species can be told apart from feral geese best by the more slender, elegant neck, which is thick-set in domestic geese; these also have a generally heavier body and often lack black wingtips.

Physical charateristics

The Ross’ Goose is a small goose, similar in appearance to the Snow Goose. Like the Snow Goose, the Ross’ Goose has a light and dark morph, although the dark-morph Ross’ Goose is extremely rare. The light morph is white, and the dark morph is gray with a white head. Both morphs have black primaries. The bill is small and lacks the ‘grin-patch’ seen on the Snow Goose. Juveniles are mostly gray.
Ross’ Geese are usually in flocks, often mixed with Snow Geese. Their tendency to roost in tight flocks and be easily attracted to decoys may have made them vulnerable to market hunters, who had a significant impact on the population. These geese typically forage on the ground, wading or swimming in shallow water.

Listen to the sound of Rosss Goose

[audio:https://planetofbirds.com/MASTER/ANSERIFORMES/Anatidae/sounds/Rosss Goose.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.:	119	cm	wingspan max.:	137	cm
size min.:	53	cm	size max.:	66	cm
incubation min.:	21	days	incubation max.:	24	days
fledging min.:	0	days	fledging max.:	24	days
broods:	1		eggs min.:	4
			eggs max.:	5

Range

North America : North

Habitat

The Arctic nesting grounds of the Ross’ Goose, not discovered until 1938, consist of tundra, marshes, and ponds. In winter and during migration, these geese can be found in shallow lakes, fresh-water marshes, flooded fields, and other agricultural lands.

Reproduction

Ross’ Geese breed in colonies, starting in their second or third year. The nest is on an island or the shore of a tundra lake, often situated at the edge of a low thicket. The nest, built by the female after she lays her first egg, is a bulky pile of leaves, grass, and moss, depressed in the middle and lined with down. The female lays a total of 4 eggs and incubates them for about 3 weeks. The young leave the nest shortly after hatching. The parents lead the young to water and food, and the goslings feed themselves. The male stands guard and actively defends the young against predators. The young fledge at 40 to 45 days.

Feeding habits

Almost exclusively plant-eaters, Ross’ Geese eat grasses, sedges, and grain. In the fall, they eat more seeds and grains than grasses.

Video Rosss Goose

httpv://www.youtube.com/watch?v=sgzXh6pdB74

Conservation

This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
In the Nearctic region the population of Ross’ Geese was estimated at only 2,000 to 3,000 individuals in 1931. Protection from hunting has helped the Ross’ Goose population recover to a 1988 total of 188,000 breeding birds, although it is still listed as a species-of-concern on the Partners in Flight watch list. Still on the increase, populations are now thought to be expanding their range greatly–birds have been found farther east and west in recent years during migration. Most nesting occurs within a refuge, and hunting is still prohibited, but loss of migration stopover and wintering habitat continues to threaten the Ross’ Goose.
Commonly held in wildfowl collections, and most European records (e.g. Faeroes, Britain, Belgium, Germany) regarded as escapes. In Netherlands, records include apparent vagrant returning November 1994 for 8th consecutive winter.

Migration

Migratory, main wintering area in California (Sacramento Valley), but also in New Mexico and along Gulf Coast of USA. Vagrant elsewhere in North America and perhaps in NW Europe, though some escapes certainly involved.

Distribution map

Rosss Goose distribution range map

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