Introduction
This is the 22nd
year of our study at Leighton Moss RSPB. It was an interesting year with good
productivity and survival.
Breeding
Population and Survival
This year we have
either re-trapped or re-sighted a total of 15 adult females and 11 adult males.
Past experience is that we always miss a few and this would suggest a breeding
population of ca 18 pairs. Survival this
year has been most interesting. Of 31
adults known to be alive in 2012, 15 were present in the breeding season of
2013. This gives a crude survival rate
of 49%. The lower numbers of grit tray sightings obtained this year has probably reduced the numbers of adult re-sightings. However 49% survival rate is about average for adults in years with reasonable winter
weather. However of 17 juveniles ringed
in the 2012 breeding season no less than 12 survived to the 2013 breeding
season, a survival rate of 77% and the best survival rate yet recorded for
juveniles and only the third year in the 22 years of the study that juvenile
survival has been better than adult survival. Overall this gives a survival rate of 60%, one
of the highest yet recorded.
Productivity
Productivity was much better this year with 48
ringed although one un-ringed bird was seen in late October. After a cold start, which surprisingly did not delay
breeding the weather was good with a low
water level so no flooding out of
natural nests. Of 21 nestlings ringed 16
were caught as juveniles so survival at
this stage was good.
Grit Tray Sightings
A total of 191
sightings of colour ringed birds were obtained between August 24th and December
17th on the grit trays. A
total of 54 different birds were recorded, 24 adults and 29 juveniles. Total
sightings were 114 down on 2012 probably due to the mild autumn with large
numbers of insects present and a low water level, allowing access to the substrate.
John
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