Saturday, 27 April 2013

Waxwing lyrical part 34 - counting down

The number of Waxwings continues to decline each day. The birds have been piling on weight and the weather has been generally favourable for migration so there is nothing to hold them back once they are ready to go. The graph below shows the numbers I have recorded each day since the first bird turned up and shows the trend in numbers. During March there were still plenty of berries around and numbers didn't really take off until the end of March when the berry supplies had been exhausted and the birds also started to fatten up.

copyright P J Alker

The weight increases some of the birds have shown recently is quite impressive - NW31951, a first winter female, weighed 62.8g on 20/04/13 but weighed 74.3g when retrapped this morning, an increase of 11.5g in 7 days or 18.3%.
NW31942, an adult female, weighed 63.3g on 19/04/13 but weighed 78.5g when retrapped this evening, an increase of 12.2 g in 8 days or 19.3%.

Apples may not be a natural food supply in spring but the data is still valuable and a good measure of their ability to put on weight. The birds are actually less dependant on the apples now and are also feeding on the emerging flowers of various trees. I have seen them feeding on Poplar flowers recently and the emerging flowers of Ash today.

There must be significant nutritional and or energy value in the emerging flowers given the effort the birds put in to get at them. I have  also seen quite a few Wood pigeons feeding on Ash flowers in the past few days.
I only caught 1 new and 4 retrap Waxwings today but one of the retraps was my favourite bird if you can ever have a favourite Waxwing. It was the colour-ringed bird from Aberdeen that was first seen in the garden on 18th February. This bird is a first winter female and has been recorded in the garden 32 times since then and has been caught 4 times. She hasn't shown the rapid weight increases of some birds but is making steady progress. She only weighed 49.3g on 30th March but was 63.0g when retrapped today.

NW65022 retrapped today.
She was first seen on 18th February amd her details can be found by clicking here.
This afternoon I dragged myself away from the Waxwings and surveyed one of my river sites as I normally would at this time of year. A Dipper was carrying food but the nest was inaccessible and a net across the river only produced a Kingfisher although they aren't known to nest on that particular stretch. There will be plenty for me to do once the Waxwings have finally gone but I may have a lie-in or two first.

Kingfisher (Alcedo atthis) 27/04/13

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