01 September - 02 September 2018
The pace of avian migration starts to really accelerate as we get into September and we detected this trend in some of the species we banded this past weekend. The number of birds we trapped was not huge, but we caught some consequential species that contribute to our knowledge of birds not seen at SpruceHaven during the breeding season, but moving through as they depart Ontario to spend the northern winter in Central and South America.
Neotropical Warblers and Flycatchers (among others) are two distinct families that can provide identification challenges at times and our constant companion is "Pyle," the bird bander's indispensable guide.
As any bird bander will tell you, a bird in the hand can look quite different from the bird you observe flitting around in a tree, or in flight. And by having the bird in the hand and being able to take wing measurements, weight, and examine other characteristics it is in most cases possible to identify the sex and age of the bird.
Take for example, this Black-billed Cuckoo (Coccyzus erythropthalmus).
Pyle tells us that the orbital ring in an after hatch year bird is red (as opposed to greenish or dusky in a hatch year bird) and that the the shape and pattern of the outer rectrices show a rounded tip with a white terminus.
The red orbital ring is shown in the picture above and the details of the rectrices are shown below.
Putting all this information together we can confidently identify this bird as an adult (AHY) bird.
You can see the mosquito bites on Ross' forearm above - the price bird banders pay for plying their craft at this time of the year.
We were able to identify this Wilson's Warbler (Cardellina pusilla) as a hatch year male based on the large, but mottled cap, and other plumage characters.
We were able to identify this Wilson's Warbler (Cardellina pusilla) as a hatch year male based on the large, but mottled cap, and other plumage characters.
It was very pleasing to be able to process a Yellow-bellied Flycatcher (Empidonax flaviventri), a species we see infrequently.
Whether this species could have been identified in the field is open to question. Empidonax flycatchers are notoriously difficult when they are not singing and several species are very similar indeed. Compound this lack of vocalization once the breeding season has passed, with less than perfect light conditions, rapid movement high in treetops and the fact that the bird is smaller than most leaves, and identification sometimes verges on alchemy! One has to be content often with the designation Empidonax species.
Take a look at these two pictures of Black-throated Blue Warbler (Setophaga caerulescens) taken from my files.
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| Male |
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| Female (picture from Internet Bird Collection) |
The minute white flash, along with other characters, enables us to confidently identify this bird as a hatch year female Black-throated Blue Warbler.
In a female hatch year Nashville Warbler (Leiothlypis ruficapilla) the characteristic rufous patch on the head of this species is absent, as shown in the photograph below. The buffy eye ring is also diagnostic.
Bird banding is fascinating, challenging and very rewarding. Over time it contributes in no small measure to our understanding of the life histories of birds.
Banders the world over are linked by a common passion and a dedication to helping the birds we love. For an excellent treatment of bird banding (ringing) in the UK see the excellent blog of my good friend Phil Slade https://anotherbirdblog.blogspot.com
All species banded 1, 2 September: Black-billed Cuckoo (1), Yellow-bellied Flycatcher (1), Traill's Flycatcher (1), House Wren (1), Nashville Warbler (1), Magnolia Warbler (3), Black-throated Blue Warbler (1), Wilson's Warbler (1), Song Sparrow (3). Total: 13 birds of 9 species.
Retraps: Grey Catbird (1), Common Yellowthroat (1), Magnolia Warbler (1), Song Sparrow (1).
