TURNSTONES
turning stones to see what's underneath
COUES'S ARCTIC & MEALY REDPOLL (2018)
- ID of a male Coues's Arctic Redpoll in Meijendel, Wassenaar, the Netherlands
- ID notes on undertail coverts: use this feature carefully!
Figure 1. Coues's Arctic Redpoll, male, Varanger, Norway, April 2012
Species, subspecies, basically I don't care. I've got a thing for redpolls (one of the reasons: see here). Their plumage variation is fascinating, no matter how we label them. In this article I take a closer look at the undertail coverts of Mealy Redpolls (Acanthis flammea flammea) in relation to Coues's Arctic Redpolls (Acanthis hornemanni exilipes).
Figure 2. Coues's Arctic Redpoll, adult male, Meijendel, Wassenaar, the Netherlands, 7 January 2018. The direct winter sunlight gives this bird a slightly warmer appearance. Also see pictures made in the shadow below.
Let's start with my first ringing day in 2018. After many weeks with lots of rain and strong winds, the weather finally cleared on 7 January. With Mealy Redpolls on the move it turned out to be a fantastic day: 86 were trapped, a national “spring” record!
And YES: a beautiful adult male Coues's Arctic Redpoll! The first one ever to be ringed at our site (since 1927)!
The following features were noted:
- A large, pure white rump (measured at 1.8 mm); streaking started between 2nd and 3rd tertial
- Pure white undertail coverts
- It was the greyest bird of the day (direct comparison with 10 MR, incl. 4 ad males)
- Uppertail coverts with broad pale edges; centre greyish brown
- Flank streaks very fine
- Breast pinkish rather than reddish, on a limited area
- Edges of tertials broad and pure white
- Pale cheek
- Mostly white wingbars; wingbar on medium coverts white and relatively broad
- Edges of tail and primaries with broad white edges
- Fluffy bird
- Greyish "shawl" in the neck
Coues's Arctic is variable, just like Mealy and not everything on this bird is "classic". The size of the bill - though a bit smaller than a few males Mealy ringed at the same time - was not unlike I've in seen in other Mealy Redpolls, so it wasn't obviously small. It even looks slightly convex. The head shape is also not unlike Mealy. With this bill-head combination it doesn't look like it crashed into a wall - like the most obvious Coues's do. Birds with a structure similar to Mealy do however occur. Finally there's some pinkish on the cheek - rather unusual according to Demeulemeester (2017).
However, the sum of positive features justifies the ID. What a fantastic start of the year!
PS With the lack of moult contrast, the rounded shape of the tail feathers and the pinkish red breast this is an adult male.
Figure 3. Limited amount of pinkish red on the breast, limited streaking on the flanks and fluffy appearance. Figure 3-7 same bird as Figure 2.
Figure 4. Coues's with adult male Mealy Redpoll (upper bird).
A= note the colour difference: mostly grey with a brownish hue vs. brown-grey in Mealy
B= white edges of tail feathers broad vs. smaller edges in (this) Mealy
And oh yes, note the large white rump.
Figure 5. With adult male Mealy Redpoll (on the right).
A= broader and whiter edges of greater coverts than in (this) Mealy
B= note broader and whiter edges of tertials
C= note broader and whiter edges of primaries
Figure 6. Note the very large, unstreaked rump and broad greyish edges on the uppertail coverts.
Figure 7. Immaculately white undertail coverts.
Speaking of untertail coverts...
Undertail coverts of Mealy and Arctic Redpolls
Many features are very variable in Mealy redpoll. The overall impression of individuals can be surprisingly different. Some are darkish grey brown, others give a paler grey-brown impression. I always check pale birds for Coues's Arctic. The undertail coverts are the first feature I check when I release a bird from a mist net.
Now let's see what the books mention about this. These illustrations are from Svensson (1992):
Figure 8-9. Undetail coverts of Mealy Redpoll and Arctic Redpoll (from: Svensson 1992)
And these from Demongin (2016):
Figure 10. Undertail coverts of Mealy Redpoll (from: Demongin 2016)
Figure 11. Undertail coverts of Arctic Redpoll (from: Demongin 2016)
In the late autumn and early winter of 2017/2018 I studied the undetail coverts of c. 75 adult males more extensively.
I ringed quite a few Mealy Redpolls with undertail coverts that look good for Arctic.
Results
A lot has been learnt about the variation within Mealy Redpoll since Svensson (1992). A quarter of a century later Demongin (2016) mentions that in adult Mealy undertail coverts (hereafter: utc) are "occasionally unstreaked". Well, they certainly are!
I'd say males that show utc that match Arctic are perhaps a minority, but that doesn't mean they are rare. It occurs more often than I thought! At least nine birds I ringed showed utc that would fit Arctic: that's about 10% of the males in this small (and not strictly defined) sample size! In four birds, the utc were even more or less perfect for Arctic.
Now these utc (Figure 12) are more or less "average" for a male Mealy. The longest utc is well marked (dark and broad; arrow shaped) but other utc are also marked:
Figure 12. Mealy Redpoll, adult male, Meijendel, Wassenaar, the Netherlands, December 2017. These type of markings on the undertail coverts - dark brown, arrow-shaped on the longest, other coverts also marked - are common in Mealy Redpolls.
Some males are less well marked. Take a look at this one (Figure 13). The shape and size might match Arctic, but the markings are not restricted to the longest utc.
Figure 13. Mealy Redpoll, adult male. With two undertail coverts with small streaks, this is a poorly marked individual. Meijendel, Wassenaar, the Netherlands, 9 January 2018. This individual is not included in the nine birds that have undertail coverts that match Arctic. I've added this pic to show part of the variation in Mealy.
Now it becomes more interesting. Only the longest utc is marked in this bird (Figure 14-16). I'd say this fits a darker Arctic (but perhaps not an adult male): it is even less well-marked than than the most extreme Arctics in both Svensson (1992) and Demongin (2016). I trapped at least five birds with comparable utc in less than 2 months.
Figure 14-16. Mealy Redpoll, adult male, Meijendel, Wassenaar, the Netherlands, 7 January 2018. Though obviously marked, these undertail coverts should be possible on Arctic Redpoll.
Four birds however, showed utc that no Arctic Redpoll would be ashamed of - not even the males. Three of these birds only showed a greyish shaft streak. Check the two birds below that only have a pale grey streak on the longest utc (Figure 17-20)
Figure 17-18. Mealy Redpoll, adult male, Meijendel, Wassenaar, the Netherlands, 24 November 2017. These undertail coverts fit Arctic Redpoll, with only a faint and fairly short streak on the longest covert.
Figure 19-20. Mealy Redpoll, adult male, Meijendel, Wassenaar, the Netherlands, 7 January 2018. Another bird with only a small and fairly faint streak on the longest undertail covert.
But in this third bird, I'd call the streak on the longest utc hardly noticeable (Figure 21-24). I'm pretty sure this will go unnoticed in the field in all but the most favourable conditions.
Figure 21-23. Mealy Redpoll, adult male, Meijendel, Wassenaar, the Netherlands, 9 January 2018. This bird is even less marked on the undertail coverts than the bird in Figure 19-20.
Here's a close-up. Just note how small and faint the streak on the longest utc is!
Figure 24. Mealy Redpoll, adult male, Meijendel, Wassenaar, the Netherlands, 7 January 2018. Close-up of undertail coverts, same bird as Figure 21-23.
And, finally, there's this fella: a Mealy Redpoll with completely white undertail coverts (Figure 25-26).
Figure 25-26. Mealy Redpoll, Meijendel, Wassenaar, the Netherlands, 7 January 2018. Bird with completely unmarked undertail coverts.
Conclusions
In this fairly small - and admittedly not wel defined - sample size (an estimated 75 males), roughly 10% of the adult male Mealy Redpolls showed undertail coverts that can also be found on Arctic. Four of these birds even showed what could be defined as perfect for adult male Arctic. In three birds a (very) faint shaft streak on the longest covert was all that was present. The 4th bird even had immaculately white undertail coverts. Though this type of undertail coverts is only found in a minority of the Mealy Redpoll males, I wouldn't say that it's rare. Especially with the large number of birds that roam around during an invasion, a small percentage can still produce a high number of individuals with this feature. Note however that Demeulemeester (2017) mentions that birds without undertail cover markings often show extensive pink on the underparts and rump, which allows them to be identified correctly as Mealy Redpoll.
Undertail coverts are important to ID a vagrant Coues's Arctic in the Netherlands. It's a good marker in the field, a reason to check a bird, but identifying Arctic is always about using a set of characters, so use it with care!
References
Demongin, L., 2016. Identification Guide to Birds in the Hand. Beauregard-Vendon.
Demeulemeester, M. 2017. Identification of Redpolls, a compilation (2017 update).
Svensson, L. , 1992. Identification guide to European passerines (1992). Stockholm.