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Ringing at Ashleworth Ham

Visit 11 on 21 August 2018

The conditions for catching birds were perfect, slightly overcast, and only a light breeze. The trouble is that, in order to catch birds, there need to be birds present. The complete absence of bird sound whilst putting up the nets, soon materialised into the second lowest catch of the year. Whilst not totally unexpected, it is always disappointing to have fears confirmed. The catch of 30 birds was well below the averages (48 for last five years, and 52 for the full twenty previous years). The hedgerows are full of fruit, and a few insects are around, but for the time being, the birds appear to have left the site, a feature that has been noted in previous years. Numbers pick up again in mid- to late September, and good catches are obtained in October.

Whitethroat topped the list with six birds caught, closely followed by Blackcap and Redstart with five of each species. All five Blackcaps were re-traps, of which two were adults in full annual moult. Two each of Redstart and Whitethroat were re-traps, one of the Whitethroats being an adult in annual moult.

The Redstarts were all juveniles at different stages of their post juvenile moult. Two were females fully moulted out, but still recognisable as juveniles by the orange fringes on the greater coverts, the other three were males, one obviously so as it was nearly through its moult, the other two were only just recognisable as males, as their moult had just reached their heads, and a few white feathers were just beginning to show through their protective sheaths. It is this opportunity to see these intimate details of a bird’s life cycle, that is one of the major appeals of ringing. For the scientists studying populations, the data from Ashleworth show that in this area, Redstarts have had a successful breeding season, with 22 of the 31 individuals handled this year being juveniles.

Chiffchaffs on the other hand appear not to have done so well locally.  Most years at this time, the sound we hear most frequently is the disyllabic call note of the young birds keeping contact with each other. This year there is little or no sound of them, and the catching figures reflect this, each visit yielding an average of just over one bird per visit, compared with last year when each visit yielded 8.4 birds per visit, and 5.8 birds per visit in 2016. It will be interesting to see if visit 12 (the final CES visit) does anything to change these statistics, but it is doubtful if it will.

Mervyn Greening

Ringing at Hasfield Ham

by Mervyn Greening

Visit 10 on Tuesday 14 August 2018

The electric fence, to protect the netting area from cattle, was re-instated yesterday, and was still standing when operations started this morning. Weather-wise, the conditions could not have been better, slightly overcast and with the gentlest of breezes. Whilst the nets were being erected it was noted that there was virtually no bird sound. So, despite the perfect conditions, it was no surprise that catching was very slow.

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If it hadn’t been for the arrival of good numbers of migrating Swallows and House Martins, some of which descended low enough to be caught, the catch would have been well below the average of 57. As it was the catch, with the hirundines, was slightly above average at 63. Of the regular birds, Whitethroat was top of the list with nine caught, followed by Bullfinches with six.

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Of the 63 birds caught, only five were adults, four of which were in post-breeding moult, while one had completed its moult. All the hirundines were birds of the year which had completed their rapid, short, and incomplete post-juvenile moult, which will be finished when they reach their winter quarters. Young Swallows look like adults, but with much subdued colours, especially the throat which is rusty rather than red. House Martin juveniles on the other hand look quite different from the adults. Their plumage is more the colour of Sand Martins, as the blue tinge to the black feathers is not developed until post-juvenile plumage. When the birds are in the hand, and the rump (which is white) and the underparts are not readily visible, then the head alone could easily be mistaken for a Sand Martin.

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During the morning the cattle paid us a visit, and the effectiveness of a fully operational electric fence was demonstrated, when the herd tried to walk through the hedge where the nets are, only for the leading cows to touch the fence and jump back; this in turn caused confusion for the cows behind which ran off. Question now is, do the others learn from the ones in front? Or do they all have to touch the fence at some time to know what it does?

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One of the interesting things for me at this time of year is seeing young birds at different stages of post-juvenile (PJ) moult. A multi-brooded species like the Robin, can have young ranging from birds still completely in juvenile plumage, up to birds of the year that have completed their PJ moult and look exactly like adults. It’s also interesting to see the difference in the speed at which PJ moult happens. Long distance migrants like Swallows have a rapid and incomplete PJ moult; Chiffchaffs and Willow Warblers have a partial PJ moult of all their body feathers (but not flight feathers) which takes a few weeks; Wrens which have a similar strategy, stay in juvenile plumage a long time, then have a rapid moult; and Long-tailed Tits have a complete moult so are indistinguishable from adults by September.

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Not all birds are healthy, and sometimes individuals are caught which cannot be ringed. Bullfinches and Chaffinches sometimes have mite infestations that cause their legs to develop growths. Such was the case with one of the adult Bullfinches caught today. In this male bird, the infestation has made the legs and claws grow unevenly and bigger.

This is the report from CES visits 5 to 9 to Ashleworth Ham:

Ashleworth Ham CES visits 5-9 (PDF).

Posted on behalf of Mervyn Greening.