Crakes on the scope I: Baillon’s Crake

“So, my theory is hot dogs are not actually dogs, despite what they teach you in school.”Greg. Over the Garden Wall (David Smith, 2014).

Regardless of their country of origin, every European birder would agree that crakes are undoubtedly among the most glamorous species of the continent.  All 3 species regularly occurring in the region are considered to be real skulkers, but from time to time you can come across a showy individual putting on a great show.

They have all the ingredients to be sought-after: they are migrants, variably scarce and we all have a place nearby where they can potentially pop up, but usually don’t. Always on the candidates list for being the yearly highlight of a basic local patch. Spotted Crake seems to be the most generous in that respect, with apparently a wider variety of suitable habitat and usually appearing in degraded areas. Little Crake is more exquisite but still regular and entirely expectable at some hotspots, whereas Baillon’s Crake is almost a rarity that can randomly appear anywhere.

This year however, all three species are offering point-blank views and one can even choose between different individuals of each species, all giving an amazing show. With the increasing coverage of some secondary wetlands and small rivers and the fact that nowadays every birder wears a camera, a quick look through the birding portals reveals an unprecedented gallery of stunning Crake photos, all taken in Catalonia during the last week. Indeed it’s a perfect chance to take a look at plumage variation. The purpose of this series of posts is to put up some insights on age and sex differentiation in all three species, using some photos taken during last week’s bonanza in addition to some other images I had stored in my library. Thanks, first of all, to all the observers who’ve found these birds and, second, to all the photographers who’ve kindly shared their pictures with this blog.

Overview

According to most references (Demongin 2016, Baker 2016), all three species perform a partial post-juvenile moult that includes body feathers and, in some species, some wing coverts (including tertials in Little and Baillon’s). Adults, in the other hand, undertake a complete post-breeding moult. The existence and extension of a pre-nuptial moult is still unclear, as well as whether it’s related to a particular age-class or not. Anyhow, it might only include some body feathers.

Baillon’s Crake

This species can breed opportunistically depending on habitat availability, especially in relation to the intensity and duration of the African rainy season. Birds in the Senegambia area can breed during the winter and produce more than one clutch per breeding season if the extensive sedge and grassland area they use is still flooded (Seifert, et al. 2012). The entire population migrates as soon as it gets dry and, despite their destination and movements are still poorly understood, the genetic studies show a significant exchange between African and European grounds suggesting some connectivity between these areas (Seifert, et al. 2016).

With this in mind, we should expect a lot of variation in terms of wear, since such an elastic breeding season might lead to a very elastic moulting period too. Also, we should also consider the possibility that some of the birds we see in spring could be 1st calendar year (hereafter “1cy”).

One of the birds that is showing well these days at Besòs River (La Llagosta, Barcelona) looks surprisingly juvenile-like, quite dull and showing almost entirely brown cheeks and brown-tipped breast feathers. The contrast between brown upperparts and bluish underparts isn’t sharp and the black-and-white region in the rear flanks and vent isn’t as extensive and well contrasted either.

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Figures 1 & 2. Baillon’s Crake Porzana pusilla. Besòs River, La Llagosta, Barcelona. March 2019 © Marcel Gil Velasco. This bird shows a very dull appearance, combined with black and fresh primaries.
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Figure 3. Baillon’s Crake Porzana pusilla. Besòs River, La Llagosta, Barcelona. March 2019 © Marcel Gil Velasco. Detail of the primaries. Note that they are in much better condition than the bird in Figure 6. One could tentatively say these primaries aren’t as broad, but the actual shape is hard to assess.

An immature is probably the first that comes to our minds but there’s something that doesn’t quite fit: the primaries are all very fresh. What are the options then?

  • An adult female: the state of the primaries seems to fit with a complete post-breeding moult and the overall dull colouration should exclude a male. However, the species is not meant to show such a noticeable sex dimorphism.
  • A 1cy (or close to) of unknown sex. That would mean this bird was born last winter, probably in Africa, and migrated north afterwards. Primaries are fresh because of their short age, but the plumage isn’t entirely juvenile (compare it to the one in Figure 4), indicating a very early partial post-juvenile restricted to body feathers. It’s worth noting that a quick look through the eBird gallery shows similar individuals, all of them with surprisingly fresh primaries, supporting the 1cy theory. Common Quails, a species reasonably close to crakes, famously follow the same strategy.
  • A 2cy of unknown sex. It would make sense that 2cy birds show such dull plumage, but, to be that fresh now, the primaries must have been moulted in either a complete post-juvenile or a complete pre-breeding. This moult doesn’t happen in classical 2cy (Figure 5), which also show a brighter appearance overall.
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Figure 4. Baillon’s crake Porzana pusilla. Wadi Al Mughsayl, Oman. November 2017. © Marcel Gil Velasco. An individual with an entirely juvenile appearance.
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Figure 5. Baillon’s crake Porzana pusilla. Ridaura River Mouth, Girona. April 2013. © Rosa Matesanz. Note entirely juvenile flight feathers but adult-like appearance overall.

Let’s now add the bird at Empordà Golf, Gualta (Girona), into the equation. This bird has been present in that area since last weekend, allowing great views too. It shows a much brighter plumage: there’s no brown on the cheeks, the contrast between brown upperparts and much highly saturated underparts is very sharp and the black-and-white region in the rear flanks and vent is more extensive and well-contrasted. The primaries are intriguing though, with an apparent moult limit between P6 and P7 and a subtle difference in wear (and maybe shape) between P5 and P6. Admittedly, the wear increases gradually outwards, but the change from P6 to P7 seems to steep for being just a matter of exposure. The question is whether this is an adult with a suspended complete or a 2cy with an extensive post-juvenile. The shape of the outer primary should shed some light on this, but sadly it’s too hard to assess in these photos.

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Figures 6 & 7. Baillon’s Crake Porzana pusilla. Golf Empordà, Gualta, Girona. March 2019. © Joan Goy. A much brighter individual.
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Figure 8. Baillon’s Crake Porzana pusilla. Golf Empordà, Gualta, Girona. March 2019. © Joan Goy. Detail of the primaries of the bird at Golf Empordà. Note that wear increases outwards, but the contrast between P6 and P7 is very strong.

Regarding the sex, if the dull appearance of the bird at La Llagosta is due to age and not to sex, then this bird should probably be left unsexed, fitting the low sexual dimorphism stated in the literature. If the difference is due to sex and not to age, then this bird is surely a male.

In conclusion, Baillon’s Crake has at least 3 different plumages: one in autumn easily assignable to 1cy birds (Figure 4), a dull but already brown-and-blue (Figures 1 – 3) and the typical adult-like plumage (Figures 5 – 8). Surprisingly, birds with a very dull appearance in spring seem to show very fresh primaries (Figure 3), whereas birds brighter overall show either juvenile primaries (Figure 5) or a putative moult limit around P6 (Figure 8). Keeping in mind how variable and habitat-dependent breeding season is, I find it quite plausible that dull birds like the one at La Llagosta are just a few months old, born in Africa like many Quails, and that the putative moult limit in adult-like individuals is just a suspension, as happens with other opportunistic breeders typically around the tropics. 2cys, just as the bird at Ridaura, would then show an entirely juvenile wing (p-j moult restricted to body feathers, as expected) and there wouldn’t be much sexual dimorphism (also as expected). In-hand analysis of both dull-plumaged and adult-like birds in spring is critical in order to clarify the situation.

References

Baker, J. (2016). Identification guide to European Non-Passerines. A BTO Guide. British Trust for Ornithology,

Demongin, L. (2016). Identification guide to birds in the hand. Cambridge: Cambridge University Press.

Seifert, N., Becker, P., & Flade, M. (2012). Breeding in a postulated wintering site: first evidence for the breeding of Baillon’s Crake Porzana pusilla in Senegambia, West Africa. Ostrich, 83(2), 79-84.

Seifert, N., Haase, M., Van Wilgenburg, S. L., Voigt, C. C., & Schmitz Ornés, A. (2016). Complex migration and breeding strategies in an elusive bird species illuminated by genetic and isotopic markers. Journal of Avian Biology, 47(2), 275-287.

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