The Lincolnshire Bird Club

The Mid-Lincs RG had a routine autumn ringing session today. Thrushes were noticeable by their virtual absence though finches were moving through all morning. Birds ringed were:

1 Sparrowhawk (m)
1 Great Spotted Woodpecker (f)
7 Blackbirds
1 Song Thrush
7 Wrens
2 Robins
8 Dunnocks
13 Blue Tits
7 Long Tailed Tits
11 Goldcrests
7 Meadow Pipits
1 Yellow-browed Warbler (m)
1 Blackcap (m)
9 Goldfinches
3 Chaffinches
4 Lesser Redpoll
6 Reed Buntings

One of the Goldfinches had a Belgian ring. Other birds of note seen were 1 Peregrine, 1 Merlin and 2 Jays.

Your posts always set me thinking and remind me of how little I know. How do you sex a Yellow-browed Warbler? What about other Phylloscopus warblers?

Robert

Robert,
I was toying with sending the following by private message but I hope there are a few Forum readers who may be interested in how ringers reach their conclusions. One of the most important books in a ringers box is Lars Svensson's "Identification Guide to European Passerines." It collates his own findings plus further biometrics recorded by over 60 European ringers/ornithologists (including our own Alan Ball's study results on Lapland Buntings.) Generally speaking, most passerines can be identified by the presence or absence of a brood patch during the breeding season. Biometrics taken at that time can lead to positively sexing birds at other times of the year.
In the case of Yellow-browed Warbler (Phylloscopus Inornatus), initial findings by Ticehurst in 1938 and subsequent research gives the range of wing and tail lengths of either sex - todays bird had a wing length of 58mm and a tail length of 42mm which falls solely in the range of males. In the case of Phylloscopus Warblers, only Artic, Pallas's, Greenish and Willow can be similarly sexed outside the breeding season.
Like any other science, things move on year by year so it's important to consult the latest research papers - that's why ringers are continually learning!
Hope that helps,
Stuart

It does help, thank you. However it prompts another question: how does one know that those individuals with brood patches are female?

Robert

In the case of quite a few species, only the females brood - hence the brood patch. In a lot of earlier research, the biometrics were gained from dead specimens which were sexed as a result of dissection.