Waterfowl of North America: SWANS AND TRUE GEESE Tribe Anserini
The approximately twenty extant species of swans and true geese are, unlike the whistling ducks, primarily of temperate and arctic distribution, especially in the Northern Hemisphere. It is thus not surprising that continental North America may lay claim to at least nine breeding species, or nearly...
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DigitalCommons@University of Nebraska - Lincoln
2010
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| Online Access: | https://digitalcommons.unl.edu/biosciwaterfowlna/9 https://digitalcommons.unl.edu/context/biosciwaterfowlna/article/1008/viewcontent/Swans_and_true_geese.pdf |
| Summary: | The approximately twenty extant species of swans and true geese are, unlike the whistling ducks, primarily of temperate and arctic distribution, especially in the Northern Hemisphere. It is thus not surprising that continental North America may lay claim to at least nine breeding species, or nearly half.of the known total. Additionally, sufficient records of a tenth, the barnacle goose, are known as to warrant its inclusion in the book even though there is no indication that it nests in continental North America. Several additional Old World species of geese and swans have been reported one or more times in North America, but the likelihood of at least some of these being escapes from captivity seems so great that their inclusion seems unjustified. These species include the red-breasted goose (Branta ruficoIlis) , which has been collected in California at least five times and has also been seen in recent years in Texas, Pennsylvania, and Kansas, but is not known to nest nearer than central Siberia. The bean goose (Anser fabalis) has been reliably reported from Alaska (Byrd et aI., 1974), while the smaller pink-footed goose (A. f. brachyrhynchus) has been collected in Massachusetts (Bent, 1925) and seen in Delaware (Audubon Field Notes, 8:10, 9:235). Other Old World species that have been reported, such as the lesser white-fronted goose (Anser erythropus) and the bar-headed goose (Anser indicus), appear to have represented escapes from captivity, although a specimen of the former species was recently shot in Delaware (American Birds 27:597). Geese and swans are generally large waterfowl that are almost entirely vegetarian in their diets. Swans forage predominantly in water, eating surface vegetation or tipping-up to reach underwater plants, but occasionally resort to eating terrestrial plants on shorelines or even in fields. Geese, however, forage both in water and on land, with some species such as brant foraging exclusively on aquatic life while others rely largely on terrestrial herbaceous plants. In most ... |
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