Spotlight on Autumn Redstarts

HeaderAutumn 2015 is so far proving to be a great period for Common Redstarts moving through Northants. The first migrant appeared on 1st August, followed by another the next day and then, from 14th August, they have been seen almost daily with records from 13 sites. Most reports involve 1-3 birds but an exceptional 10 were present in scrub between Pitsford Res and Walgrave yesterday.

Some of these are ‘brown’ autumn birds, which are a challenge to age in the field so, prompted by some recent online discussion regarding the ageing of an autumn female, I pulled together some images of local birds to look at in more detail.

All adults undergo a full post-breeding moult, while first-winters undergo a post juvenile moult which is restricted to head, body, lesser, median and some/all tertial coverts and one or two inner greater covets. The upshot of all this is that all Common Redstarts seen in early autumn will have relatively fresh plumage with lots of bright fringes to the wing feathers.

Svensson (Identification Guide to European Passerines) states that, even in the hand, ageing according to plumage characteristics is very difficult with, on some first years, contrast between one or two fresh inner greater coverts and the slightly worn remaining greater coverts plus more pointed tail feathers on first-winters being the most reliable ageing characteristics.

However, both BWP and Van Duivendijk (Advanced Bird ID Handbook, The Western Palearctic) state that, as well as tail feather tip shape, the middle (BWP) or inner (Van Divendijk) primaries will have distinct pale tips as opposed to very uniform, narrow pale fringes on adults. The presence of rusty/grey tips to the greater coverts is shown by both adults and first-winters, so is not a valid ageing characteristic. BWP goes on to suggest that the tertials of first-winters are more pointed and have broad, buffy fringes  while those of adults are squarer with little or no buffy fringes.

Here is the image which sparked the discussion.

Female Common Redstart, Brampton Valley, 30th August 2015 (Douglas McFarlane)

Female Common Redstart, Brampton Valley, 30th August 2015 (Douglas McFarlane)

Based upon the above criteria (complete narrow fringes to primaries, medium narrow fringes to tertials and nearest outer tail feather appearaing rounded) this an adult. Compare this below with a typical spring female with worn plumage.

Female Common Redstart, Northampton, 3rd May 2010 (Bob Bullock)

Female Common Redstart, Northampton, 3rd May 2010 (Bob Bullock)

Here’s what I would call an obvious first-winter, showing all the classic features associated with a first year bird. Broad buffy fringes to tertials, broad pale tips to middle/inner primaries and apparently pointed tail feathers. The underparts also look a little scaly.

First-winter Common Redstart, Clifford Hill GP, 5th September 2014 (Mike Alibone)

First-winter Common Redstart, Clifford Hill GP, 5th September 2014 (Mike Alibone)

Below is what appears to be another first-winter, although not so well defined as the individual above. Middle tail feathers look rounded, though outers look pointed.

Common Redstart, Wellingborough, 29 August 2015 (Barbara Nunn)

Common Redstart, Wellingborough, 29 August 2015 (Barbara Nunn)

Here’s an undisputed adult female, trapped in summer and found to have an active brood patch – so a likely local breeder. Well worn and no sign of any fringes.

Adult female Common Redstart, Stanford Res, 5th July 2015 (Adam Homer)

Adult female Common Redstart, Stanford Res, 5th July 2015 (Adam Homer)

For completeness, below is a first-winter male, already wearing and surprisingly little fringeing.

First-winter male Common Redstart, Stanford Res, 1st September 2015 (Adam Homer)

First-winter male Common Redstart, Stanford Res, 1st September 2015 (Adam Homer)

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One Response to Spotlight on Autumn Redstarts

  1. Pingback: The Week in Focus: 29th August to 4th September 2015 | Northantsbirds

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