At risk of repeating the same overall message, 2009 was yet another 'interesting' year; by which we mean that it was different from the previous 3 years in a variety of ways. It gives strength to the argument that to really get to know a site in any detail requires many years of continuous study.
Now that most of our net sites at Belvide are consistent from year to year, they have become well trampled so access to them in early July does not pose any risk to species which may still be nesting. In addition, the water levels were lower than in recent years, meaning that we were able to start the 'post-breeding' ringing programme earlier than ever on 8 July, and continue until 19 September.
In 2009, for the first time, we also embarked on what we hope will be a long-term study of those breeding birds using the many nest boxes around the reserve. The results from this are, as is often the case, raising as many questions as answers at this stage, but we look forward very much to continuing this study, the results of which are reported later.
Finally, a small amount of netting at the reed-beds was done in November and December for Reed Buntings. Small numbers were coming in to roost, but this year unfortunately no Starling roost developed.
The table below shows the numbers of new birds ringed in 2009. Overall the year provided the largest number of new birds ringed so far; which is consistent with the early results from the national Constant Effort Sites Scheme which suggests that 2009 was a good year for breeding success for many small birds. However, as can also be seen, the variety of species ringed was lower than in recent years. This need not cause real concern since the main 'core' species were present in good numbers; and often the number of species is a function of chance and extra effort in certain ways. For example if weather conditions are right, it's possible to catch many hirundines and Swifts; if not , then we don't catch any, even though there are still plenty in the area.
|Species||Ringed 2009||Ringed 2008||Ringed 2007||Ringed 2006|
|Great Spotted Woodpecker||0||5||0||0|
|Stock Dove||0 + (2)||0||0||0|
|Long Tailed Tit||25||26||35||50|
|Total||1389 of 31 sp.||1299 of 45 sp.||833 of 32 sp.||788 of 26 sp.|
Indeed, the only new species ringed this year, resulted from a chance encounter — Moorhen — and increased effort with nest boxes, in that the Stock Dove chicks were raised in one of the boxes erected to attract Barn Owls.
Of the non-passerines, although there are some year-on-year differences, it's probable that none of these are significant. For example, we caught no Sparrowhawks this year, but individuals were present. The lack of woodpeckers was probably due to a reduced catching effort at the feeding station, and the large number of House Martins was one of the chance occurrences mentioned earlier where weather conditions on one morning were such that this species was forced low to catch insects.
We have grouped the resident breeders into three loose categories. The first group appear to be in a steady state: Blackbird, Song Thrush, Treecreeper, Bullfinch, Greenfinch and Goldfinch all had insignificant variations in numbers caught suggesting there are holding their own.
Dunnock and Chaffinch both appear to have had very good breeding success with more young birds caught this year than ever. All 59 Dunnocks were juveniles with no new adults ringed. Several adults were re-trapped from up to 4 years ago — it seems that this population of adult Dunnocks have pretty well got the place to themselves, and are obviously very good at defending their territories against interlopers. Coal Tit also increased, but there may been a chance that this was because perhaps one pair bred this year compared to none in the recent past.
Concern surrounds those species which appear to have had a poor breeding season. Given the similarities between Robin and Dunnock lifestyles, it's a puzzle as to why Robins appear to have fared so badly this year. Perhaps it is easier to account for the lower numbers of Wren, Goldcrest and Long-tailed Tit. All three are well known to be vulnerable to cold snaps, of which there were more in early 2009 than in previous years, so the suggestion here is that the adult breeding stock was hit before breeding started. However all three species are also known to be able to bounce back given milder winters so let's hope. The smaller number of Tree Sparrows is probably not significant — at least judging by the numbers of un-ringed birds at the feeder at any given time. The reduced ringing effort at the feeder is probably the reason.
Summer visitors overall did quite well. It's always difficult to know if numbers are due mainly to breeding or to birds calling into the reserve on migration. Whichever is the case, the numbers do give an indication of breeding success, either at Belvide or wherever birds have come from.
Reed Warbler numbers are creeping back to the high levels of 4 years ago. The low water levels have undoubtedly helped with strong reed growth, which was combined with generally very good weather during the summer. Of the birds ringed 13 were un-ringed adults, probably from breeding colonies elsewhere, although none were bearing rings. Unfortunately we did not carry out a supplementary survey of actual nests. We hope that the clearing of areas of willow scrub will increase the available breeding habitat for this species in future years. Sedge Warblers are showing the same pattern, perhaps even more related to the low water levels this year providing more suitable breeding habitat.
Of the 'Sylvia' warblers, Whitethroat, Lesser Whitethroat and Garden Warbler appear to be relatively stable, with Blackcaps having a particularly good breeding season. The low water levels, dense bramble scrub and decent weather all seem to have promoted a good breeding season for this species, with most of the regular adult birds being re-trapped, and 83 young birds ringed.
Both Chiffchaff and Willow Warbler had their second highest totals in recent years. Chiffchaff appear to be breeding well in the area, and these numbers are bolstered by passage migrants — 3 birds were caught bearing rings from elsewhere although details of these have not yet come through. No Willow Warblers bred on the reserve this year, so totals are based on passage migrants alone, and the generally high number is encouraging given the concern about the national decline overall in this species.
There are over 80 boxes of various types on the reserve, but apart from the Stock Doves mentioned earlier, the only boxes checked regularly and containing chicks were 45 'hole' boxes. None of the open boxes was occupied. Of the hole boxes 60% were occupied by Blue Tits and Great Tits.
19 boxes held Blue Tit broods, from which 156 chicks fledged, giving an average fledging success of 8.2 chicks per nest, with a range of brood sizes from 2–13, as shown below.
|Brood size||Number of broods of this size|
By any standards this feels like a good year for Blue Tit breeding and it will be interesting to compare these figures year on year. Weather conditions at fledging time were good so there is a good chance that most of these chicks will have at least had the opportunity of establishing themselves as independent individuals after leaving the nest.
With this in mind we have been monitoring the number of these chicks which have subsequently been caught on the reserve. The results have been as surprising as they are difficult to explain. Of the 156 Blue Tit chicks which fledged in May/June, only 14 were re-trapped later in the year. The very high mortality rate in small birds undoubtedly plays a part in this, but some results suggest it is more complex than this. For example individuals X355349 and 409 were not recaptured at all through the summer, but were trapped at the Gazebo feeder in mid November. Could it be that, contrary to our initial hypothesis, young tits do not simply hang around in their breeding area, but move out to explore their surroundings (as well as being chased away by their parents), and some move back into the area as they become more experienced/assertive? We will need to monitor this in future years.
11 boxes held 59 chicks giving an average brood size of 5.4, with a range of between 8 and 1, as shown below.
|Brood size||Number of broods of this size|
A very similar pattern is seen with Great Tits. Of the 59 fledged chicks, only 2 were ever re-trapped: TL 448415, and 430 were caught at the feeder in July, and neither they nor any of their fellow fledglings has been re-caught. Clearly there is a lot more work to be done.
Another very successful year has put a few more pieces of the jigsaw in place, but equally other puzzles have been thrown up. The scrub clearance carried out during the latter part of 2009 looks promising in terms of opening up some areas for possible breeding of species such as Willow Warbler. The concentration of willow bushes around netting areas may also concentrate available birds near the nets: only time will tell if next year's catch will be significantly different. We hope to make a concerted effort to count and monitor Reed Warbler nests in 2010, providing the water levels make it safe for us to do so.
As ever, great thanks go to the West Midland bird Club for extending our permit to ring at Belvide; we hope that the range of ringing demonstrations has enhanced the interest/experience of the many visitors to the site. Continuing support from the Belvide management team in so many ways is again much appreciated; we hope that the findings help in some way towards the continued successful development of the site as a great place for both birds and birders.
Colin McShane on behalf of Brewood Ringers; December 2009.
Belvide Reservoir Nature Reserve is situated near Brewood, Staffordshire, England, seven miles north-west of Wolverhampton, at grid reference SJ870099.
Ornithology in Staffordshire, Warwickshire, Worcestershire & the West Midlands county, since 1929.
Fetched fromon Thursday 23 May 2013 22:17:56
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