Friday, 20 May 2016

Starling RAS 2016

Over the past few weeks most of my ringing effort has been directed at my Starling RAS which runs from 21st April to 24th May each year. A total of 129 different adult Starlings were recorded in the garden during that 5 week period last year and all of those birds were colour-ringed. Fewer adults have been recorded this year with a total of 85 individuals recorded to date but that number could still increase as there are a few days of this year's RAS period to go.

Adult male Starling
Although the number of adults is down on last year's total, 62 of the 85 were resightings or recaptures of birds ringed prior to the start of this year's RAS period and only 23 were new birds. More importantly 47 were birds from last year's RAS period which gives a provisional re-encounter rate of just over 36%. This is very good re-encounter rate for a RAS project of this type and means the project is on track to provide high quality data on adult survival when analysed in more detail by the BTO.

The local Coal Tits have no problem dining with Starlings.
The most striking feature of this year is that Starlings have bred a good two weeks earlier than they did last year (in this area at least). This can be illustrated by the occurrence and ringing of juveniles in the garden with the first juvenile ringed on 7th May this year compared to 22nd May last year. In addition 105 juveniles have been ringed up to and including today and I didn't reach that number until 4th June last year with a similar amount of effort, so it certainly isn't a case of a few pairs nesting early.

Juvenile Starling coming out of the trap that it was caught in just a day or two before. I catch Starlings using a very simple cage trap, operated by a pull cord, and this allows me to be highly selective. Once Starlings have been colour-ringed there is no need to recapture them so they are free to take advantage of the food in the trap as often as they like and a great many do. This has the advantage of attracting unringed birds into the trap which I usually manage to catch without retrapping any previously ringed birds.

I also have a fat block feeder near the trap that is specifically positioned to make it easy to read the numbers on the colour-rings. Birds happily move between this feeder and the food on offer in the trap.

Juveniles are not intimidated by the adults and have no problem competing for food.

The abundance and availability of soil invertebrates, especially leather jackets, is one of the factors that could influence the number and frequency of adults visiting the garden. Observations at a nearby playing field suggests there is more natural food available this spring and that may be one of the reasons behind the smaller number of adults recorded in the garden this year. It is also likely to be a factor in this year's earlier nesting.

Starlings feeding on the nearby college sports pitches.

Another factor affecting the number of adults is likely to be the ongoing loss of nest sites due to property improvements. The replacement of old wooden soffits and facias and or the pointing up of gable end ridge tiles potentially results in the loss of up to 4 nest sites on a single property. A few houses are 'improved' in that way around here every year so the population seems set to decline irrespective of other factors unless more people can be persuaded to put up Starling nest boxes to compensate for such losses.

More information on RAS projects can be found  here,  here  and  here.

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