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Archived Postings

August 6, 2007 – August 12, 2007

A full month of fall migration monitoring has passed at the LSLBO and we have finally banded our 1000th bird. Unfortunately, we were not keeping an accurate tally and are not exactly sure which bird it was. We do know that the 1000th bird had come a little slower than in previous years. Our records show that in some years over 1000 birds have been banded by the end of July. We are not concerned about the slower banding because our records also show years when the second half of August has seen the busiest banding of the season. We will patiently wait to see what the rest of August offers. Meanwhile, migratory activity over the past week ranged from days with heavy passage and lots of banding, to days with little passage and little banding, to rainy days with no banding taking place at all. Yellow-rumped warblers and chipping sparrows were the top two species observed migrating this week. It was interesting to see that the chipping sparrows were only migrating in good numbers on the rainy days and yellow-rumped warblers were moving on the sunny days. I do not have an explanation for this movement pattern. Rain days are a little dull because we do not open the mistnets and there are usually very few birds moving about. Watching the chipping sparrows migrate in the rain provided a little excitement to a rather slow day. A few new species were also seen passing through this week, including: eastern kingbirds, northern harriers, and more sharp-shinned hawks. Ovenbirds and Swainson’s thrushes were being captured in large numbers and are quickly becoming two of the top banded species banded of the fall. But they may have trouble overtaking the American redstarts, who are sitting in number one spot and are still being banding in good numbers. Lately, these three species seem to be dominating the net checks. It is a nice break from the norm when a different species is mixed in with them, like our first blue-headed vireo of the fall. Blue-headed vireos are very good looking birds and it is unfortunate that we do not capture more of them. Blue-headed vireos are one of the four species of vireos that are seen at the LSLBO. The other three vireo species are the red-eyed vireo, warbling vireo, and Philadelphia vireo. We have now captured at least one bird from all four species of vireos. It is a nice accomplishment to have banded at least one of each species representing a family within a season. There are 51 different species of vireos in the Western Hemisphere. Of the fifteen found in North American, only the four listed above are seen at the LSLBO. All the species of vireos have a couple of common traits. The common physical feature is the slight hook at the tip of their top mandible. Being primary insectivores, the hook of the bill is helpful in capturing their prey. The hook is also useful to defend against the fingers of a bander. The good news for us is that they do not have much power behind their bill and the worst that happens is the hook will dig into the skin a little. The other vireo family trait is the design of their nests. All vireos build hanging nests. Essentially it resembles a basket suspended from a branch of tree. The vireos encountered at the LSLBO can be difficult to distinguish by both sight and sound. The red-eyed, warbling, and Philadelphia vireos are all quite similar in plumage. It often takes more than a quick glance to be able to tell those three apart. The red-eyed, Philadelphia, and blue-headed vireos all have similar songs. The major difference between the songs is the speed in which they sing it. Identifying vireos is a challenge and it does take some practice to be able to figure them out.

2010