Wednesday, 28 December 2011

Preliminary results from the BTO 2011







The preliminary results from the British Trust for Ornithology’s 2011 Nest Record Scheme (to which we contribute by submitting all of our breeding records) indicate a happier 2011 for the nation’s Barn Owls following the disappointments of the previous year.

Nationally Barn Owls had a disappointing season in 2010, with mean brood sizes falling to their lowest level for a decade. The extremely cold winter of 2009/10 may have left females in poor condition at the start of the breeding season, reducing the amount of energy available to invest in egg production, leading to below average clutch sizes. The harsh winter weather conditions may also have affected vole numbers later in the season, although snow cover can actually be beneficial to small mammals as it shields them from predators.


Barn Owl chicks. Photo by Colin Shawyer
 Barn Owl brood sizes in 2010 (red dot) were the second lowest since 1985

Percentage breeding success in 2011 relative to the average for the previous five years. Significant increase in green; significant decreases in red.

Species
Clutch size
Brood size
Egg stage
survival
Chick stage
survival
Fledglings
produced
Kestrel
0.0
6.8
2.4
3.1
14.6
Barn Owl
7.2
3.9
1.6
1.3
1.3
Tawny Owl
1.6
6.0
-7.8
1.2
-2.1
Swallow
-1.0
-0.3
-0.4
2.1
0.6
Dunnock
0.7
-0.4
-0.6
19.0
19.7
Robin
1.4
4.9
11.6
-15.9
-1.3
Blackbird
-0.9
-1.0
-1.8
3.2
-0.1
Song Thrush
-2.2
-0.2
11.9
4.5
13.4
Reed Warbler
1.1
2.9
0.9
-1.0
3.0
Blackcap
0.5
4.5
-15.1
-7.0
-15.6
Whitethroat
-5.8
-5.8
3.8
-7.4
-12.0
Chiffchaff
-1.0
-2.9
-0.9
2.3
2.5
Willow Warbler
-3.0
1.5
-9.3
1.4
-8.0
Pied Flycatcher
2.4
1.6
1.4
-2.4
0.9
Blue Tit
-3.6
2.8
1.1
4.0
3.4
Great Tit
6.4
10.0
1.5
1.8
12.2
Tree Sparrow
-0.1
3.8
-4.3
-4.1
-6.1
House Sparrow
0.9
-1.2
0.2
1.0
5.1




 .



















Rodent specialists produce bumper broods

In contrast to the 2010 season, during which Barn Owl brood sizes fell to one of the lowest levels on record, 2011 appeared to be a very productive year for all three of the small mammal specialists included in these analyses; Barn Owl, Tawny Owl and Kestrel. Anecdotal reports of well-stocked prey larders suggest that rodents were plentiful during the breeding season, and the warm, dry spring weather provided perfect hunting conditions. Kestrel appeared to fare particularly well, exhibiting a 15% increase in the number of fledglings produced per nest, welcome news for a species whose recent population decline, particularly in England, has raised concerns amongst conservationists.
 
 Small-mammal-eating Raptors, like the Kestrel, had good breeding seasons in 2011.


Locally in Mid-Cheshire we did not enjoy the same success in terms of brood size and fledging success as that which is depicted nationally; although we did find 41 successful breeding Barn Owl pairs which managed to fledge 110 young.

Thursday, 22 December 2011

Barn Owl Windows



Clearly visible in the apex of the gable end of this old Cheshire barn is a Barn Owl window. These windows were traditionally incorporated into agricultural buildings in order to encourage the owls to take up residence. Owls were a natural means of pest control and served to keep the rodent population in check on many farms.
Note the later addition of cables below the window; this would seriously impair the flight path of any bird approaching or leaving the barn. The use of these windows has declined to the extent that their use is now minimal and the provision of alternative nest sites is consequently one of our conservation priorities.


Today, on a really sunny December morning, we put up a couple of new boxes on the south side of Middlewich. Peter is posing underneath the latest addition to our box portfolio!


Thursday, 15 December 2011

2011: A summary.




As a busy 2011 draws to a close we can reflect upon what turned out to be a pretty good year for Mid- Cheshire's Barn Owls. After two harsh winters we were not really sure quite what to expect in the breeding season and whilst the year was not our best it still turned out to be quite productive.

We located 41 successful breeding pairs which managed to fledge 110 young. Additionally I ringed 18 new adult birds and 22 were found from previous years. One of our birds which was ringed as a chick near Whatcroft in 2005 had the bad taste to fly south to Shropshire where she is still breeding successfully. She is now the oldest breeding Mid-Cheshire bird that we know about.




This splendid female has bred for three consecutive years in the Lach Dennis area and has managed to raise seven young birds in that time. Her second brood of four birds in 2010 however, had not manage to fledge.


This female is the most heavily marked individual that I have ever come across and she also has bred for three consecutive years near Weaverham. She has managed to raise thirteen young birds in that time. Sadly one of her brood was found dead on the roadside at Oakmere in September.

Birds that fly into the path of traffic represent the biggest killer of Barn Owls in Britain and of the eight dead birds that have been recovered in 2011, six were the victims of road side kills. One was found frozen to death last winter and the other had flown into a building, sustaining a broken neck as a consequence.

The year has also seen us erect 43 new boxes and replace 17 of our older ones. Birds seem to readily take to the new boxes and this week I found out that this male bird is still roosting in a box that was replaced in October.


We look forward to 2012 and hope that we can continue to enjoy more of these magnificent birds in our countryside.

Saturday, 12 November 2011

A short life.


This little chap was the last owlet that I had ringed this year back at the beginning of September. He had managed to fledge successfully and had left his natal site moving 4km to nearby Wincham.

In early November, at 11 o'clock in the morning (I suspect that he had been disturbed from his roosting site), he flew into an office window and sustained a broken neck. His short life had only lasted a couple of months and serves to demonstrate how perilous life is for newly fledged owls.