Ode to a wader

6 05 2013

“Tell me what you’d like to hear me sing. I’ll sing whatever you like, after which I will take up a collection, if you don’t mind…”

– Edith Piaf

It’s not the first time I’ve realized my life has changed by looking at which species I am targeting at work. One year ago, I wrote a similar post about Laurel pigeon and today, it’s time to take a look to another species that is breeding close to the place where I am living: the Dunlin. These 2 species seem to share opposite fates: while Laurel pigeon is experimenting a notable increase due to hunting prohibition and habitat protection, Southern dunlins Calidris alpina shinzii are declining dramatically.

Calidris alpina

Everybody knows the Arctic is in serious trouble. The increase of the global temperature together with the accumulation of contaminants is leading most of Arctic species to extinction. However, the firsts changes in their populations can be noticed further south, in the little spots of tundra (or its equivalent southern moorland habitats) where these species do also breed. Sometimes these areas are well-protected and local researchers are not able to explain why the population of such species keeps on decreasing. In these cases, the conservation strategies must be global, acting in the heart of the populations, sometimes in places where a decline has not been noticed yet. This means to study the still healthy populations, assessing their threats, even if they come from further south like contaminants or occur further south like human pressure in wintering grounds. To ensure the main range of a species guarantees its future and it would be the species itself who would send advanced scouts to establish satellite populations in this isolated southern spots of habitat.

Vellinge Angar

Vellinge Angar2

I am working in one of those spots: southwestern Skåne. The population of dunlins here is fragmented and declining despite the big effort performed by local researchers. Vellinge Ängar is already my favourite area among the 8 comprising the breeding bird survey. It’s a beautiful wet wasteland, with some channels across carrying water from the adjacent farmland area to the main lagoon. Migrating waders forage along the muddy shore, always in large numbers, while the breeding species display in the middle of the heath. Oystercatchers, redshanks, lapwings, ringed plovers, avocets and of course the dunlins make up a orchestra that plays every morning, even (who knows if especially) when there’s nobody to enjoy it.

In the first visit to the area, I saw 4 males dunlin and 2 females. All the males were crazily singing, but both females seemed to belong to the same lucky male, a very old one ringed (as an adult) in 2006. Males are supposed to take care of the brood and therefore a shorter bill is positively selected, since it is useful to forage in terrestrial habitats. The short bill is also typical of Southern populations C. a. schinzii, so the short-billed impression in males schinzii is quite impressive. Moreover, the date of arrival of breeding dunlins seems to be correlated with bill length and body mass. The pairs composed by a small and short-billed male and a big and long-billed female (like the gorgeous TC) arrive earlier to the breeding grounds, while the pairs composed by average-sized birds arrive later (Jönson 1987). Most of the birds I saw were short-billed males and long-billed females, what make me hope yet another arrival of dunlins in the following days.

female TC yellow

male R_green L_red_white

Despite this fact, the number of dunlins in the area already represents a remarkable increase with respect to last year’s numbers. A promising breeding season for them, in the end! There’s still a long way to success, but at least the initial settings couldn’t be better.

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