Sunday, 26 September 2010

The Non- Empirical Approach to Empid Identification.

from 'The Random Approach to Bird Identification'.

With the occurrence of yet another Empidonax Flycatcher in the UK, in the somewhat unexpected location of Blakeney Point, Norfolk, I thought it might be a good idea to vaguely analyse the factors involved in identifying these tricky vagrants. Accepted knowledge in the USA, where they naturally occur, is that they are generally tricky all the time, but that come autumn (fall), and with non-calling birds, id is generally speaking impossible. To identify them requires capturing them (mist nets usually, shotguns generally frowned upon these days, in the uk at least), and carrying out a complicated in-hand analysis of wing length, comparing wing ratios and p-numbers ... Codswallop, as real birders in the field will testify ...
To satisfactorily identify your chosen empid, the factors included below (but not restricted to), and probably in the wrong order as regards importance, should be ascertained and taken into account;-
Bill length and shape
Wing and tail length
Apparent wing and tail length
Head size relative to body
Presence and position of crown peak
Overall size
Eye ring shape and strength
Upperpart plumage tone and colour
Underpart plumage tone and colour
Contrasts eg wings, throat to rest of plumage
Presence of shawl, breast band etc and degree
Throat colour
Lower bill colouration
Behaviour eg tail flicking
Time of year
Which ones you haven't seen in the uk before
Etc etc ...

Jizz based id is perfectly satisfactory, in my opinion (which admittedly, counts for very little. But we won’t dwell on that minor point …)
Firstly, of course, you need to find your empid. This is the first tricky bit, admittedly. Prime spots are the extreme south west, and a blasted shingly bit of Norfolk, the only places where they can be guaranteed 100%. Iceland is good, as is North America. Good luck with anywhere else. They must be out there. Alternatively, butt in on the id of any rare empids which happen to be found elsewhere on the internet. To start with, everyone else will be as ignorant as you, so you have a reasonable chance of looking intelligent and genned up, at least initially. It will probably all go downhill pretty soon, but hey ...

If you are in the fortunate position of finding an Empidonax flycatcher, multiple photos should always be taken, avoiding direct sunlight if possible. Even better if they can be taken of calling birds on last years vacation stateside (although of course you may not want to overly emphasise this point should you decide to submit your sighting to any rarity committees, or release the news (late of course) to the general birding public (the Masses)...). Multiple observers, as long as they are suitably respectful minions, or at least on your side/with poor eyesight and equally overly keen to get a tick no matter what, may be of assistance/useful. Multiple discussions on multiple internet forums should be avoided at all costs, as differing opinions may well be received, and non-birding numpty killjoys will invariably come out with the line ‘but they can’t be 100% identified’ or similar whining drivel ...
Field experience is always useful, but so last year. The modern birder has an array of websites he can view at a moment notice (admittedly some may be of dubious use, and the bird stated as being in the photo you are looking at may not necessarily even be of the same genus/kingdom even. But 80- 85% accuracy is probably plenty enough ... ) And you can always over-emphasis what little experience you do have. For example, I have personally seen 33% of all the Empidonax flycatchers to be seen in the uk to date (50% of all species seen ... possibly ...), and if I include ones that birding compatriots have seen, and the remaining one I've read about, I can even stretch that to 100%. Impressive, huh? ... As always, careful avoidance of stating certain key facts and ambiguous turn of phrase can be useful in these matters ...

Getting the bird to call is obviously useful, given the reliance placed on this feature of bird id by some (possibly including the birds themselves), although some think it is highly overrated (deaf people?). There is always the option of getting a mate to attempt to tape lure the bird from behind the bushes the bird is frequenting. If you cannot see him/her, and they are directly in line with you and the bird, there is always a chance you can convince yourself that the bird in question is even doing the calling itself. Or it may even respond (same thing really, especially if it is partially obscured by foliage when it calls).

Willow - a thick whit
Alder - flat pep
Least - a sharp pwit
Yellow-bellied - a clear rising tuwee
Acadian - a sharp pyew or psee

(Be suitably wary of overflying Oystercatchers, Children etc.)

Trail mix - a popular misconception is that Alder and Willow Flycatchers are so similar that they can't be identified, even in the hand. Maybe autumn 1st winters can be a little tricky, but, as long as you are a properly enthusiastic observationally based birder, and not bogged down by excessive reliance on the need to only believe in biometrics (ie you're a bander/ringer/observatory warden from the 80's), then there is hope most of the time. These kind of wrinkled old fruits and other nuts encountered in the field should always be avoided/their opinions discounted out of hand. Identifying a bird as a Traill's Flycatcher (the former name for Alder/Willow) is a bit of a cop-out in all honesty.  From a uk perspective there should be no problem in assigning any particular individual to one or the other species, given the fact that the british list does not include 'possibles' or 'species-pairs'.
Basically if it looks like a typical individual of one of the following; Least, Willow, Alder, Acadian, Yellow-bellied, then it probably is. Abberant  individuals of one species can look like any other. It’s things like this that make birding in the field rubbish, so ignore the fact that aberrant individuals can exist and everyone will be happy. Ensure that any photos showing ambiguous features remain on your harddrive, and write a glowing description of 'how the 'underside of the 3rd toe/extant of rectal bristling' etc actually appeared to you at the time', when you thought about it afterwards. The 'best fit' approach, or something like that. Easy peasy. Don't know why certain so-called 'bird experts' make bird id so difficult for themselves and others ...

(Hybrids? We most sincerely hope not ...)

Good luck!  (Not that you'll need it of course ... )

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