Friday, 11 April 2014

Fun with finches.

The baited site at Longshaw is still holding a few Bramblings but it isn't easy to gauge numbers and the birds have been proving quite difficult to catch. On my last visit, a week ago, I managed to catch 5 which isn't bad for April but I had hoped for a few more. The birds are clearly taking full advantage of the sunflower seeds for fattening up for their return migration to the breeding grounds and while most of them weighed in at 23 to 24g one weighed in at a whopping 31.4g.

When I went and topped up the feeders yesterday afternoon there were still around a dozen Bramblings present so I decided it would be worth trying another ringing session there this morning. I was joined by Wayne and Steve and we had a couple of nets up before sunrise. We retreated to a vantage point to watch for any birds coming in and it wasn't long before the first small group arrived and circled overhead.  More birds joined them and soon there were at least 25 Bramblings which is a a really good number given the date. They all dropped down to the feeders and we expected a decent catch but the first check of the nets only produced 1 Brambling and 1 Willow Warbler. We did manage to catch another 5 Bramblings subsequently along with a couple of Chaffinches, a Chiffchaff and the first Blackcap of the spring but not as many Bramblings as expected given the number present.

One of today's fine male Bramblings
One of 3 Blackcaps seen or heard at Longshaw today and the first to be ringed this spring.  
Although there was very little in the way of passage overhead I also tried playing Redpoll on the MP3 lure. This resulted in 3 Lesser Redpolls being caught during the morning. Interestingly the first 2 were already wearing rings and we had ringed both of them at another baited site just over 5km away to the east with one of them having been ringed there only yesterday and the other having been ringed there on 1st April. Although they hadn't moved far such movements are interesting, especially when one is so quick. Perhaps the birds are moving between favored feeding sites over quite a large area or these birds could be moving towards their breeding areas.

On the subject of Redpolls we have caught and ringed 91 in the past few weeks and now have them coming to feeders at 2 sites. The vast majority have been Lesser Redpolls as would be expected but we have caught 5 'Mealies' or Common Redpolls if you prefer. However there have been a few birds that have made us look twice because they almost seem to be intermediate between Lesser and Mealy in appearance. All of these birds look colder and greyer than a typical warm brown Lesser, especially when seen side by side. These greyer looking Lessers are not unusual in spring and presumably get these colder tones as a result of plumage wear although it is interesting that it doesn't happen to them all. This creates significant variation in appearance and I am sure it would be quite easy for some of these to get identified as Mealies.

Variation in Lesser Redpolls with a typical warm brown bird on the left and progressively colder and greyer birds centre and right. The right hand bird was ringed very early in the morning and the light levels did affect the white balance of the picture as can be seen by comparing the colour of the skin tones of my hand and the vegetation in the background but it was still the palest of all 3. Lighting conditions can make a big difference to how they appear to the eye as well as the camera.

This Lesser had quite a pale rump, elements of pale tram lines on the mantle and greyish tones to the feathers around the ear coverts.
And 2 proper Mealy Redpolls to finish with but there is variation even here with the right hand bird being that bit browner and less frosted looking. There was an obvious size difference in all the Mealies we have caught even if they had the same wing length as a Lesser. They always looked longer overall when compared side by side with a Lesser of the same wing length.

No comments:

Post a Comment