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Anatomy of a Range Expansion
Tracking the Eurasian Collared-Dove's spread across North America A new bird has landed on the continent, and it might be coming to your neighborhood soon. FeederWatchers in Florida and other parts of the Southeast may already be familiar with the Eurasian Collared-Dove, but the rest of us ought to be on the lookout as well. A 1987 article in American Birds (Vol. 41: 1370Ð1379) describes in detail the spread of this species in North America through the mid-1980s, so the following is just a brief sketch of events. The story of the Eurasian Collared-Dove is captivating. A century ago, this species was found primarily on the Indian subcontinent, although its range extended slightly into Europe, in Turkey. In the early 1900s, however, the species began expanding its range significantly and by 1950 had reached the British Isles. Today, collared-doves are living above the Arctic Circle in Scandinavia. While this activity proceeded in Europe, two things happened on this side of the Atlantic. First, a similar-looking species, the Ringed Turtle-Dove, was introduced in South Florida and other locations in the southern United States several decades ago. These introduced birds soon established feral yet seemingly human-dependent populations, so field guides began including pictures of Ringed Turtle-Doves. Second, collared-doves were introduced into the Bahamas in the 1970s, and their populations soon expanded around these islands. What happened next is unclear. At some point in the 1980s, Eurasian Collared-Doves migrated, without assistance, from the Bahamas to Florida. And because they look much like turtle-doves, the collared-doves started to spread unnoticed. It wasn't until the mid-1980s that ornithologists realized the suddenly prolific and quickly spreading "turtle-doves" they were watching were actually Eurasian Collared-Doves. The collared-doves haven't stopped expanding their range since they arrived in North America. One bird even spent last winter as far north as eastern Montana. Eurasian Collared-Doves may be spreading across North America in much the same way they spread across Europe earlier in this century, and we'd like FeederWatchers to help document this dove's current and future range. Unfortunately, Ringed Turtle-Doves are common cage birds; thus, escaped turtle-doves could appear almost anywhere in North America. This is the challenge for Feeder- Watchers who have a potential collared-dove at their feeder. To learn how to distinguish between these two species, see the BirdSource Feature on the Eurasian Collared-Dove's Expansion. And here's an extra hint: if you already have Mourning Doves coming to your feeder, compare the size of the new dove with the Mourning Doves. Eurasian Collared-Doves are larger than Mourning Doves; Ringed Turtle-Doves are smaller. Please let us know about any collared- or turtle-doves you see at your feeders, even if you cannot positively identify the species. If possible, take a picture of the bird and send it to us. Our thanks to all FeederWatchers who have reported Eurasian Collared-Doves. Keep up the good work. |
