Tuesday, 9 August 2016

Fabulous forty.

It looked like there would be a few hours of suitable weather this morning but it was still a case of fingers crossed and a final check of the rainfall radar before setting off. I headed up to Billinge a little later than planned but still had the first net set up by sunrise and another two nets soon after.

We are just at the start of the main migration period for Tree Pipits and most will have gone through by the end of August so I want to get out whenever the weather looks suitable, even if it's only for a couple of hours. It is also the peak time for Willow Warbler migration so that just added to the incentive to get out this morning

Three Tree Pipits were caught in the first couple of rounds which was a really promising start but unfortunately none were caught or seen after that. A check of the rainfall radar on my phone showed that a band of heavy showers had developed to the north of the site and that may have been the reason they stopped moving.

One of today's Tree Pipits was this cracking adult.

Tree Pipit adult (left) and first year (right).
There doesn't appear to be a great deal of difference in the coverts of these two birds but the first year has paler fringes to the median coverts, greater coverts and tertials and they are more abraded. Many first years replace some median or greater coverts so there is often some contrast between the new and old feathers. However, the first year on the right hasn't replaced any of its coverts so there is no contrast to be seen in this particular individual. 
While Tree Pipits didn't move through in any number the same couldn't be said for Willow Warblers. There didn't seem to be that many around at first but the final tally of 40 new birds and 1 retrap made it the hightest total recorded at the site. It all happened quite quickly with all but 1 being caught by 09:00. The retrap Willow Warbler was originally ringed as a juvenile in July 2014 and was caught again in April 2015 but not handled again until today.

The tips of this Willow Warblers tail feathers had snapped off along the line of a fault bar.

A closer look at the tail. Fault bars are a line of weakness that can develop in feathers due to a shortage in nutrition when the feathers are growing. In extreme cases the feathers can snap along the line of weakness. There were 2 other similar examples in the Willow Warblers caught this morning.
Chiffchaff was a notable absentee today with none caught or present in the vicinity of the nets. This was quite a surprise as I expected to catch a few with so many Willow Warblers being on the move. If it hadn't been for the Willow Warblers it would have been a very quiet day although I would have been happy catching the 3 Tree Pipits on their own.

Ringing totals (retraps in brackets) for 09/08/2016 were: Blue Tit 1; Great Tit 1 (1); Long-tailed Tit 1; Willow Warblers 40 (1); Blackcap (1); Whitethroat 3; Tree Pipit 3; Goldfinch 2; Reed Bunting 1 (1). Total 52 new birds and 4 retraps.

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