Thursday, September 4, 2014

Ross’s vs. Snow Goose

For Erika and me, one of the more interesting sights at New Mexico's Bosque del Apache National Wildlife Refuge in early March were the large numbers of Ross's Geese. In this photo, two Snow Geese are landing in the foreground. Note their large size and black lines (grinning patches) along their bills. The two geese immediately behind the first two, however, are noticeably smaller and have very short bills, which lack grinning patches. Ross's Geese often have bluish warts at the base of the bills. These patches are clearly visible on the first and third geese in the foreground of the bottom photo.

Historically, Ross's Geese were thought to be relatively rare. Their nesting grounds in the Canadian Arctic were only discovered in 1940. Additional sites were found from the mid-1950s to the mid 1990s. They mostly winter in California's Central Valley--although they are becoming more frequent along the Mississippi Flyway. Both as breeding and wintering birds, Ross's Geese are often found with Snow Geese, with which they graze on grasses, sedges and small grains.

Due to conservation efforts and changes in agricultural practices, Ross's Geese numbers have greatly increased. In one Canadian breeding sanctuary, their population increased from some 6,000 individuals in the 1950s to over 1,280,883 in 2006. Their total population is now over 2 million birds (Jonsson et al. 2013). There are so many birds that they are trampling and destroying their breeding grounds. The aforementioned authors state that drastic population control measures are in order.

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