Thursday, 17 October 2013

Fat light-bellied Brent geese have more offspring - but only if the weather's good

I pinched this neat catchy headline from Xav's twitter feed when he circulated the link to this further neat paper from his thesis.

Entitled "Environmental Conditions during Breeding Modify the Strength of Mass-Dependent Carry-Over Effects in a Migratory Bird" this paper continues on the main theme of Xav's PhD work - looking at carry-over effects in our study population of Light-bellied Brent Geese and Xav's phrasing in the headline of this post just about says it all!

So we have demonstrated that female geese in better spring body condition are more likely to successfully raise young in that breeding season (established in a few other populations too and previous Brent papers led by the Exeter team have shown this). What is new here is an examination of the role of summer breeding conditions (snow melt, temperatures, winds on migration - those sorts of factors that we might expect would have an impact on the birds directly or indirectly) which shows that if the arctic breeding conditions were poor, irrespective of birds body condition, reproductive output would be bad. 

The full article is available here and is well worth the read. Well done to all involved.

Results rolling in from the October census: headlines over 34,000 birds; hardly any young

A few weekends ago various groups of Brent-enthusiasts were out and about counting Brent; trying to get a comprehensive count in that snapshot in what is always a very short and unpredictable time window when we know the majority of the population are concentrated at relatively few manageable sites. I say manageable - it still requires the unenviable job of counting birds from the air in Iceland and the not-to-be-taken-on-lightly job of counting the very large numbers at Strangford.

Provisional results from many sites are still to be compiled but the running totals approximate to:

21,000 (Strangford)
10,000 (W Iceland)
2,000 (L Foyle)
1,000 (Tralee & Castlemaine Hbr, Kerry)

Thanks to the participants and local organisers for covering these key major sites.
A lot of other folk have submitted data from all round the Irish coast and also Wales and Scotland - thanks all.
We'll collate this and circulate the results.

What has also become apparent is that the 2013 breeding season was not a very productive one for Brent in the Canadian breeding grounds. It seems likely that we will be lucky to have more than double figures this year. We suspect that the combination of late snow melt, low temperatures and other climatic factors in the breeding range have led to this - presumably the same is the case for other species on the same flyway (e.g. Turnstone) or those that migrate south within continental North America but have the same breeding range (e.g. Greater Snow Geese). We'll put the feelers out and try to report what info we can accumulate over the coming weeks.