Thursday, 10 April 2014

Goldfinches....Gold Rush times three

Firstly from Chris,
Between 4 and 7 yesterday afternoon I trapped 34 Goldfinches, 32 of them new.
More remarkably, on entering them into IPMR that evening, I found that  7 of them, all males, exceeded the maximum weight expected by IPMR (19.6 gm).  The heaviest I had was 20.9 gm, this bird having a wing length of 83mm, which equals the maximum wing length expected by IPMR.
(It was also bigger and heavier than the female Chaffinch that I had processed a little while before it (80mm and 19.8gm)).

The heaviest Goldfinches I have ever processed before this were one at 21.1 gm (wing 82) and one at 21.0 gm. I've only had 6 before today that exceeded 19.6 gm, 4 of them in April 2008, one in April 2010, and one in May 2010.
I've also done 13 before today with wings of 83mm, 3 with wings of 84mm, and one at 85mm. No obvious date pattern here though.

A similar pattern from Wendy -
Several Goldfinches ringed this week that have been heavier than the maximum weight expected - the heaviest weighing in at 21.3g but wing length only 77mm and none with wings longer than 83mm.
There has been a noticeable increase in Goldfinches in the garden and also along the coast when out for a walk today. This fits with the same observations last year although a bit earlier as my garden peak was around the 16th April.

From the finch passage heartland of upland Boncath a similar story of very large Goldfinches passing through. Goldfinches ringed yesterday included - 6 birds over 20g - max 21.7g, though no bird today weighed over 20g. Yesterday 11 birds had  fat scores 3 or above - the max  fat score being a 6 (a 2nd year male with wing 79 and weight 20.7g) Yesterday, 7 birds with wing lengths of 80 or above - max 82. The longest wing measured today was an adult male with a wing length of 84mm.

These are interesting observations of passage birds clearly feeding well. Weight will increase during the day, but they do seem to be well above "average" size and weight birds, with some carrying considerable fat - indicative of a fair distance still to travel.

Siskin migration seems to have slowed or stopped, with all eight of my Siskins caught in the last two days showing signs of breeding.

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