Thursday 30 October 2014

Summer days

Currently on a pretty wet and windy ferry crossing back to Islay for the winter and quietly hoping i’m not going to be that guy that gets sea sick.. Which seems as good a time as any to re-start the old goose blog; once again you can get all your exciting goose related facts and anecdotes all in one place!

But for those still reading (a pretty grand assumption, i know..), you’ll no doubt be pleased to hear I’m going to start by talking about ducks. Ducks are cool. Everybody likes ducks. And over the summer I was lucky enough to work on what has to be our most enigmatic and mysterious UK breeding duck – the common scoter.

Scoters are sea ducks, spending almost all their lives in shallow seas feeding on shellfish, only fleetingly visiting a few Scottish freshwater lochs in order to breed. Because of this marine lifestyle, most people only ever see them from a coastal vantage point as a series of small black and brown dots bobbing around in the waves, which, i have to admit, has never really excited me before. But when seen close up they are actually a pretty striking bird – well, the males are at least; jet black with a splash of bright yellow on the top of the bill, the females are the classic fairly dull brown of so many duck species.

Male common scoter

Don’t let the “common” part of the name fool you – scoters are in real trouble as a British breeding bird, likely having declined by well over 50% in the last 20 years to the current population of maybe 40 pairs. We also know virtually nothing about them – which is a bit of a problem when it comes to coming up with conservation measures to stop them going extinct as a breeding bird in this country.

So it was pretty lucky that us species research folk at the Wildfowl and Wetlands Trust got some funding to investigate their breeding ecology on a couple of West Highland lochs over the summer. We started by finding some nests; easier said than done when you only have 15 females between two lochs that are both about 12 km long – serious needles in haystacks time. With a lot of effort and fair bit of luck we managed to find 9, not bad considering only 20-30 have ever been found before. We could monitor these nests using cameras and temperature loggers placed in the bottom of the nest cup to see how many hatched successfully and if they failed why, were they predated and, if so, by what? Similarly, any ducklings that hatched were followed to the point that they either disappeared, or successfully fledged. All pretty basic stuff, but never done before.

Cosy looking nest

Early impressions suggest that when nests were located within good cover (nice tall and thick vegetation, like old-growth heather) hatching success was pretty good, although some birds nested on some small grassy islands with very little cover – and these did very poorly indeed, not surprising really!

Scoter ducklings are very sweet. They leave the nest after a day or so and trundle down to the loch after mum, often a trek of a few hundred metres over rough ground and through thick, snaggly vegetation. Once on the water though, they are completely at home, diving to feed on aquatic invertebrates almost immediately, bobbing back up like fluffy corks and quickly bunching up behind an ever alert mum. Sadly though, more than half of them died within the first week – thereafter survival is fairly constant, but fewer than one in five of those that hatched survived through to fledging.

Common scoter female with week-old ducklings

Trying to reduce duckling mortality might prove tricky, but we think we can quite easily improve the nesting habitat available on these lochs – hopefully this will mean more successful nests and we get more ducklings onto the water; if mortality rates remain the same then a few more ducklings should survive to fledging. 

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