I've just returned from birding in Florida and California. Steven Mlodinow' s January 9, 2017 sighting of a Barnacle Goose at Aurora Reservoir intrigues me. A great find indeed, however I do not necessarily agree that this goose is "very unlikely of wild origin"
More and more vagrant geese from Europe are showing up each fall in North America. Go to eBird, enter Explore Data, and type in Barnacle Goose. Winter records are now strung across the Northeast from Nova Scotia to Maryland. Back in the late nineties, Jon Dunn was skeptical about whether any of the Barnacle Goose sightings that were beginning to pop up along the eastern seaboard were of wild birds from Europe. He held the predominate view that the vast majority were just free-flying feral or escaped geese. Now the origin of these winter records from the Northeast are never challenged by any of the various state records committees. So what has changed? Why the influx of wintering European geese into our continent? Populations of both Barnacle and Pink-footed Goose have seen a dramatic increase. Writing in the Waterbird Review Series in 2004, Mitchell and Hearn state that both Barnacle Goose and Pink-footed Goose breeding populations in Iceland and Greenland have exploded since the 1950s. Regularly conducted censuses of Barnacle Geese in Northeast Greenland have revealed that their numbers have risen from just over 8,000 in 1959 to over 80,000 in 2013. However, this population increase for both species has been rather linear, whereas most of the North American sightings have occurred since 2000, so the increase in population does not fully explain the increase in North American vagrancy. Simultaneously to this population increase, North American Canada Goose populations are also increasing and are ranging farther east into Greenland and Europe in the spring, summer, and fall. A friend mentioned to me that a Canada Goose that showed up in 2011 in Nova Scotia had been tagged on its breeding grounds in Scandinavia! This phenomenon encourages more intermingling with the European geese, not just in Greenland and Iceland, but the British Isles and Scandinavia as well. Both Barnacle Geese and Pink-footed are mixing into staging flocks of Canada Geese, then migrating along with them to this side of the Atlantic Ocean where they end up wintering. These increased sightings in North America are not confined to the Northeast. Right now there is a wintering Barnacle Goose in a flock of forty-five or so Greater White-fronted Geese at the Towanda Borrow Pit in Mclean County, Illinois. This is just the latest of over twenty distinct occurrences of Barnacle Goose in Illinois almost all since 2000. Most of these are December records - 2009 in Will County, 2012 in Kane County, and 2013 in Bloomington. None of these have yet been accepted by the Illinois Ornithological Rare Bird Committee. In fact, a 2015 October record of Barnacle Goose in Western Illinois (Mercer County) was documented and is currently being evaluated. But now with yet another winter sighting, it seems likely that the IORBC will accept these records as wild birds. In addition to Illinois, Arkansas has a 2010 record and Wisconsin has a 2012 record all in December when the Canada Geese flocks show up. Barnacle Geese and Pink-footed Geese are coming west and will both eventually be accepted as wild origin in the state of Colorado. Be on the lookout and carefully document your sightings. And while you're at it please find a Siberian Accentor. John Vanderpoel -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/000c01d38ef6%24a44af070%24ece0d150%24%40peregrinevideo.com. For more options, visit https://groups.google.com/d/optout.
