For today's advent calendar blog post, I am focussing on a species which is perhaps a little more suiting to the current time of year...the Purple Sandpiper (Calidris maritima). This smart little wader is a favourite of mine, with a subtle plumage of gey tones with a delicate purplish tinge in the winter, accompanied with the bright yellow legs and base of the bill. They can be tricky to spot, remaining very well hidden at high tide in its preferred habitat type: dark rocks and boulders in the splash zone around exposed coasts and shorelines. Here on Bardsey, we have a small flock of wintering birds every year, although it has gradually been declining from around 50 birds in the 2000s to just 10-15 this winter. This trend fits with its status as an Amber species of conservation concern in the UK, due to recent declines in wintering and breeding population declines.
The Purple Sandpiper assumes a very interesting mating system in its breeding areas in the Arctic tundra: when paired, the Purple Sandpipers display a long-term bond with their partner, in a relationship known as monogamy. However, characters more typical of a polyandrous mating system have also been noted: it seems that the male takes on almost all the responsibility for the parental care of the hatchlings, with very little help from the female. They display the typical 'broken wing' tactic when threatened by predators, to lure attention away from a nest or young. The food source for this species varies depending on the time of year: in the summer, a range of terrestrial invertebrates such as spiders and insects will be taken, with more of a reliance upon marine gastropods and crustaceans in the winter months.
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