Understanding Ring Ouzel declines – Innes Sim
What’s in this talk?
•Progress in 2012/13
•Review the 2012 season
•Review long-term trends in popn size, productivity, and adult & 1st year survival
•Ask what is driving the popn trend?
•Plans for 2013 and beyond
Progress in 2012/13
•Completed my PhD thesis & published a further 3 papers in scientific journals (The Auk, Ibis & Bird Study)
•Carried out the second & final year of a 2-year experiment on supplementary feeding on RZ in Glen Clunie (Davide will talk on this later...)
•Continued with the long-term monitoring of popn size, productivity, and adult & 1st year survival in Glen Clunie
Study population
•Breeding population in Glen Clunie, near Braemar, studied since 1998
•580 nest histories
•1,840 chicks and 310 breeding adults individually colour ringed
•Measure population trend, productivity & survival/return rates
The 2012 breeding season was unusually late:
Early nest mean laying dates 1998-2012
Late nest mean laying dates 1998-2012
However, there were no great effects on early nest mean clutch & fledged brood sizes...
...or on late nest mean clutch & fledged brood sizes
Population trend 1998-2009 (-67%)
Demographic analysis 1998-2009
•1st year survival was identified as the most likely demographic rate driving popn growth rate
•However, adult survival was lower than that of species with a similar ecology
Population trend 1998-2012 (-49%)
So, what caused this large popn increase in 2012?
No evidence that it was down to high reproductive success in 2011...
...or unusually high adult survival between 2011 and 2012...
However, 1st year return rates were particularly high in 2012, especially for late broods...
So, 1st year return rate appears to be driving popn growth rate...
So why was 1st year return rate so high in 2012?
•High overwinter survival?
•High survival during migration?
•High survival during late summer 2011?
•Is it all down to the size of the moorland berry crop? Moorland berries were very scarce in late summer 2012, so if they are the key factor driving popn declines we would expect to see a drop in popn size in 2013...
Plans for 2013 and beyond...
•Fit 10 geolocators to breeding adults (now received from Biotrack!)
•Hope that some adults fitted with geolocators in 2013 return in 2014...and that we can catch them...and that they work!
•Carry on with long-term Clunie monitoring of population size, productivity, survival & demography
•Write up results of feeding experiment & publish results
•Look to start some habitat management trials on RSPB reserves...