Kestrels in Gloucestershire a factsheet (to be periodically updated as more records are received) Records of Kestrel (courtesy of Richard Baatsen) give some indication of their fortunes over the past 15 years or so in Gloucestershire. There appears to be an increase in numbers, this is in part confirmed by anecdotal evidence that there is something of a recovery compared with previous years. The overall view is that any trip along the M5 (or other motorways for that matter) 20 years ago produced regular sightings of Kestrels every few miles in the late 20 th century to the point where they were considered every-day and common birds. However, as is often the case with those birds we consider commonplace, it was only after they largely disappeared that they were missed. A similar motorway trip now produces far more Buzzards than Kestrels illustrating the change in fortunes of both species. The perception that Kestrels had declined sharply towards the end of the 20 th century is borne out by statistical evidence that after persecution in the early years of the century and the withdrawal from use of Organochlorine pesticides in mid-century, the population increased towards the 1970s but began to decline again in the 1980s. The last 30 years or so seem to show fluctuations rather than a sustained decline. Never the less, it appears that Kestrels as familiar roadside birds have been more or less replaced by Buzzards which have shown a national and remarkable expansion in both range and numbers since the 1960s. There is more solid evidence of significant decline in Scotland which at present is unexplained. A hovering Kestrel is perhaps the easiest of raptors to identify, the only other predator that regularly hovers is the Buzzard but it is far less adept at doing so and presents a far bigger and broader profile than the smaller Kestrel. Kestrels also hunt by perching and watching the ground below, on posts, trees and overhead cables; when doing so, with the head bowed and looking downwards, the profile can appear to be rather hunch-backed. The two falcons most closely resembling the Kestrel are the Merlin and Hobby; Merlins are far less often seen in Gloucestershire, they are primarily winter birds here and in flight resemble a miniature Peregrine with a shorter tail and more purposeful direct flight than Kestrel. Hobbies are more streamlined, faster and longer winged than Kestrels, the wing is more sickle shaped. Hunting flights by both Merlin and Hobby are very much about chasing prey at high speed, the Merlin favours small passerines, the Hobby takes Dragonflies but will also predate on Swallows and Martins so is generally associated with water in Gloucestershire, pools and lakes for Dragonflies, the river for its colonies of Sand Martin and Swallows in the riverside meadows. On the left a first winter male bird in west Gloucestershire; the bird on the right is a full adult male in Belgium with a radio tracking tag aerial visible above the tail. The pair of birds were breeding in a nest box and being intensively studied by local naturalists there.
(Courtesy of BTO from the Bird Trends page of the web-site for Kestrel - http://blx1.bto.org/birdtrends/species.jsp?s=kestr&year=2014) Kestrels had recovered from the lethal and sub lethal effects of organochlorine pesticides by the mid-1970s, the recovery probably driven by improving nesting success, but subsequently entered a decline. Since the mid-1980s, the English population has fluctuated without a long-term trend being apparent but there are significant declines over the BBS period in England and especially in Scotland. The BBS map of change in relative density between 1994-96 and 2007-09 indicates that the increase was widespread during that period, in contrast to the longer-term trend, but that decreases occurred in Northern Ireland, north-western Scotland and in some English cities. There has been a substantial increase in the number of fledglings per breeding attempt; brood sizes increased up to 1990, but a subsequent decline has resulted in the inclusion of Kestrel in an NRS concern list (Leech & Barimore 2008). Despite its decline since the mid-1970s, the Kestrel breeds at high density in mixed farmland across much of England, suggesting that the British population might have formerly exceeded 50,000 pairs (Clements 2008). A moderate decrease has been recorded in the Republic of Ireland since 1998 (Crowe 2012). There has been widespread moderate decline across Europe since 1980 (PECBMS 2014a).
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 No. of Recrds Annual records of Kestrel for Gloucestershire 1999 2014 these are total reports covering all seasons and illustrate a slight upward trend over the period. This is a biased result because of more intensive fieldwork and surveys for the BTO Breeding Bird Survey, the National Atlas 2007-11 and most importantly, the fieldwork carried out for the NCOS Atlas and The Birds of Gloucestershire. Bias usually distorts the picture but in this case, it s a positive result, Kestrels were under-recorded in the past and we now know that recording of common birds is arguably far more important than rarities because common species trends indicate what is really happening out there in the environment. For conservation purposes, you must know what s going on before you can work out how to do something about the issues. 1400 Kestrel Total Records by Year 1382 1200 1000 874 913 800 600 471 446 696 704 632 565 693 400 350 306 200 0 6 13 124 19
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 When separated, the records for breeding season and non-breeding periods still reflect the same trend overall and mirror each other. This again reflects intensified observer effort as noted above. However, in order to confirm whether or not the increase is genuine and continues in both cases, consistently recording as much as possible is necessary. The positive trend, if confirmed to show a real increase may well indicate better breeding and survival rates, which will lead to population recovery (as has been the case for Peregrines post DDT). 900 800 700 Non-breeding - Breeding - Kestrel Breeding & Non-Breeding Records 832 600 500 400 300 200 100 0 24 11 2 83 41 14 5 257 93 229 77 319 152 340 585 106 111 550 520 354 574 339 396 308 426 206 386 509 179 184
Breeding Season Records as a %age of total records by year: Year Breeding Season Non Breeding Season Breeding Records % 1999 2 4 50% 2000 2 11 18% 2001 41 83 49% 2002 5 14 36% 2003 93 257 36% 2004 77 229 34% 2005 152 319 48% 2006 106 340 31% 2007 111 585 19% 2008 550 832 66% 2009 354 520 68% 2010 339 574 59% 2011 308 396 78% 2012 206 426 48% 2013 179 386 46% 2014 184 509 36% Breeding season records as a percentage of total records overall are not very consistent from year to year with a variation from 18 to 78 %, the average being 45%; there are only three years in which the real proportion is close to the average. There will be annual fluctuations in numbers for both breeding and non-breeding periods due to the variation in weather conditions, availability of food supply, survival rates of young from previous years and of course, the variation in observer effort in any series of years so it is unlikely that much can be read into these figures.
Distribution Maps: This is a representation of the breeding season records indicated in Birds of Gloucestershire in a tetrad format. Overall it portrays the distribution pattern of breeding birds being greater in the more open areas of mixed farmland which prevails in the Cotswolds, the Vale and North West of the county compared with the hills, valleys and wooded areas of the Dean Forest and the west of the county.
Birds of Gloucestershire - KESTREL Breeding Season Abundance 5 SO 5 6 7 8 9 0 > 0.25 SP 1 3 4 0.25-0.50 0.51-0.75 4 4 0.76-2.00 3 3 The relative abundance map in Birds of Gloucestershire makes the geographical bias towards the east of the Severn even clearer 2 2 1 1 SO 0 0 ST SP SU There is also a noticeable increase in abundance to the east and south-east in the catchment of the Thames where Gloucestershire abuts Oxfordshire and Wiltshire which both have large areas of open country and mixed farmland 9 9 8 5 6 7 8 9 0 ST SU 1 2 3
The breeding season records taken from the 1999 to 2014 period on a 1 kilometre square basis shows more gaps than in the tetrad format as might be imagined but does show a similar bias in distribution towards the same open areas mentioned above, compared with the woodland cover areas to the west of the Severn.
At a 10 kilometre square level, there is little difference between distribution maps from the BTO Atlas for 1968-72 and the latest national Atlas 2007-11; 10 k squares are not sufficiently detailed to show the change picture at local level, only at national level, also, they do not at this scale indicate gain, loss or abundance (for Gloucestershire) which is the real key to illustrating what is going on with Kestrel populations. 5 GLOUCESTERSHIRE 10 K Breeding Distribution 1968-1972 SO SP GLOUCESTERSHIRE 10 K Breeding Distribution 2007-2011 SO SP 5 6 7 8 9 0 1 3 4 5 6 7 8 9 0 1 3 4 5 4 4 4 4 3 3 3 3 2 2 2 2 1 1 1 1 SO ST 0 0 SP SU SO ST 0 0 SP SU 9 9 9 9 5 6 7 8 9 0 ST SU 1 2 3 8 5 6 7 8 9 0 ST SU 1 2 3 8 Confirmed Probable Possible Breeding Evidence No Strong Breeding Evidenc
A Forest Kestrel Nest Site: Kestrel nest site in the Forest of Dean; the nest hole had been previously used by Tawny Owl and is a natural split in the main trunk of a hollow Nelson Oak approximately 200 years old. Five eggs were laid in this instance. Kestrels are less numerous in the Dean than the Vale and Cotswolds where the open country suits them better; however, some birds nest in trees here, or in quarries, though most quarries are now dominated by Peregrines, even if not breeding there. Kestrels are more frequent on the edges of the Dean where open farmland fringes the woodland.
The eggs pictured are about half incubated, when first laid they are more uniformly reddish and have a fresh bloom ; as incubation progresses, the eggs become washed out and lose their colour. Of the five eggs laid, at least three hatched but the fate of the other two eggs was not known; the chicks in this picture have their eyes open so are several days old. They continued to grow and develop. Quarry nests sites were used in the Forest of Dean in the past, though less frequently used now due to increased tree and undergrowth regeneration since the quarries fell out of use and because of the presence of Peregrines in some places. This is a clutch of 5 eggs on a ledge in a Forest sandstone quarry where Kestrels shared the site with Jackdaws and Stock Doves.
Three well grown chicks are now approaching the point of fledging, they have all survived to this point from the stage they were at in the previous photograph above and still have the vestiges of their down; this will fall away to reveal proper feathers but only after their first moult will they begin to show their adult plumage. This chick, probably the oldest of the three in the tree nest takes a look at the big wide world he will shortly venture into. Surviving his first winter will be the greatest challenge of his life; if he makes it to the following Spring and Summer, he will probably go on to be a breeding adult for many more years.
The female dominates the feeding process, on this occasion she took food from the incoming male in the tree tops and sent him off to find more whilst she approached the nest and fed the growing young herself. Much of her time was spent in relatively close proximity to the nest between hatching and fledging whilst the male hunted all hours for the whole family.
So, what next??? Continue the gathering of records to build a more detailed picture of distribution in all seasons this will enable a view of fluctuations over a period of years and help establish trends if there are any to be seen. Find if possible and monitor nests sites, in particular, try to establish breeding success that is to say numbers of eggs laid and birds fledging fledging and survival rates are the key to successful breeding and over time, result in the increase or decrease of populations. Compare Kestrel trends with other birds of prey to some degree Kestrels share habitat and food sources with Owls so there may be some degree of similarity in trends. Possibly erect nest boxes to facilitate monitoring in suitable locations. Acknowledgements and references: Richard Baatsen (County Bird Recorder, Gloucestershire) and Gloucestershire Raptor Monitoring Group for the records BTO Bird Trends page of the web-site for the CBC/BBS data graph Birds of Gloucestershire (Kirk & Phillips, 2013, Liverpool University Press) for the tetrad distribution and abundance maps (re-drawn by Andrew Bluett) The Atlas of Breeding Birds of Britain and Ireland (Sharrock, 1976, Poyser) and Bird Atlas 2007-11, Balmer et al, 2013, BTO) for the 10km square maps data (re-drawn by Andrew Bluett) Text, other maps, graphs and photographs by Andrew Bluett