Ivel Ringing Group Report No.4 - 1996-97

Contents Introduction Highlights of 1996 & 1997 Site Reports Annual Totals Recoveries and Controls Specie's reports 10 year comparison of the percentage of juveniles caught for six commonly trapped species Juvenile Whitethroat productivity 1988-97 (update) Membership Acknowledgements

Cover: Corn Bunting (Milaria milaria) by Andy Chick (by permission E C B Newman)

INTRODUCTION This is the fourth biennial report of the Ivel Ringing Group. We hope that the information published, together with that in previous reports, is proving informative to our readers. During the period, the core membership remained at seven, three A’, three ‘C’ and one Trainee permit holders. During 1997, Amanda Proud was granted a ‘C’ permit and began to ring at her home in Bartonle-Clay and nearby Shillington, whilst maintaining her contact with the group’s Trainers. We also welcomed Tony Aldhous, a bat worker, who needed practical experience of removing birds and large insects from mist nets in order that he could be licensed to use mist nets for catching bats. This he managed to achieve in a reasonable time-scale. Our ringing totals dropped to their lowest yet in 1996, generally a bad year all round for many ringers. Productivity of young was at a low for many species that year due to the English weather. The Constant Effort Sites ringing was disrupted and the data for juveniles are inadmissible. By the end of the year we had ringed a mere 1400 birds. 1997 saw a modest improvement to the 1850 mark. We caught our second Nuthatch, controlled a Cetti’s Warbler, and had another “county first” with Yellowbrowed Warbler. We went a whole year without catching a single Linnet for the first time ever; a sign of the times, no doubt. On the computer front, a completely new (Windows compatible?) version of B-Ring from the BTO is envisaged. The current version has been found cumbersome to use by us and we will continue to use the PRO-IV program for inputting until this new version has been proved On the social side, Steve Spick and Emma Brindley tied the knot (nothing to do with wader catches!) and EN relocated to Bedford, both in 1996. Naturally, both had some effect on the annual totals. HIGHLIGHTS 1996  The end of year total was 1394 new birds ringed, including 51 pulli, plus 473 retrap handlings. This level of effort is equal to 35% of 1994 and 25% of our best year, 1991. The specie tally was a mere 43. A total of 16 birds were recovered or controlled during the year. The most noticeable characteristic of the year’s weather was its dryness. Only 70% of average rainfall was recorded. The wettest months were August (49mm) and November (58mm) of rain was recorded; neither month was exceptionally wet. The temperatures in March and May were well below average with cold winds. June and July were generally warm and dry. September was noticeable for the north and north-east winds that persisted and lack of rainfall (8mm). November and December both had significant spells of cold weather. The conditions in August and September were not conducive to catching birds at a time when we would normally expect to catch one third of the annual total. Before the weather changed, SS and AP managed to spend time in the Sand Martin colony at Manor Farm and ended up with over 250 birds in total. [If you discount these birds, it makes the final figures look even more depressing. Ed.] Numbers of Swift pulli ringed were lower than normal, due to the dry spring and early summer. 1997  The end of year total was 1863 new birds ringed, including 39 pulli, plus 581 retrap handlings. This is 35% up on last year, a move in the right direction. The specie tally was 48 (including the already ringed Cetti’s). A total of 18 birds were recovered or controlled. Yellow-browed Warbler was added to the group’s ringing list. Even though January, March and April were very dry, rainfall was 90% of average. June was generally in England the wettest this century but in Bedfordshire not as wet as June 1958. August was the second hottest since 1659, even beating record-breaking 1995. December was noted for its storms. The wetness of June may well have had a significant, detrimental effect on our birds and other wildlife. This was the year of the Cetti’s and Yellow-browed Warblers, both at Priory CP. There was a miniinvasion of the first in January. One subsequently turned up with a ring on and, following the rules, an attempt was made to catch it. Ten minutes after setting a net, it was a controlled bird. The Yellowbrowed turned up with a mixed flock of tits and warblers just before one o’clock. As this was only going to be a quick, on the spur of the moment, lunch-time session, the ‘brownie points’ bonus was very welcome. Again, a disappointingly low number of Swift pulli were ringed this year.

SITE REPORTS Note: the numbers of birds given for each year represents newly ringed ones only. Approximately 25% of all birds handled already bear a ring (called retraps if ringed on or near the same site) All sites are in Bedfordshire except for those at Gamlingay, which are in Cambridgeshire.

BARTON-LE-CLAY (TL0810) Large private garden beside the A6, close to the quarry 1996 - 107 birds of 10 spp. 1997 - 87 birds of 13 spp

BAR

The site was started in late June 1996. The top bird in ‘96 was House Sparrow with 40 followed by Blue Tit. The latter was tops in ‘97. A surprising 15 Dunnocks were caught over the two years. CHALTON STW (TL0327) Treatment works for the north of Luton (on the chalk spring line) 1996 - 68 birds of 20 spp. 1997 - 180 birds of 22 spp.

CHA

Six visits were made between March and June 1996 with 10 Sedge Warblers being the highest. One Willow Tit and two Treecreepers were interesting for an open site. Eleven visits made during the first eight months of 1997 with a good number of Long-tailed Tits ringed (see under ‘Recoveries’). Fourteen Blackbirds and 25 Blackcaps are also of note for ‘97. THE EMBANKMENT, BEDFORD (TL0649) Popular, public riverside walk and lawns alongside the River Great Ouse. 1996 - 46 Mute Swans 1997 - nil

EMB

GAMLINGAY CINQUES (TL2353) Mixed scrub and a pond (on the Greensand spring line) 1996 - 89 birds of 19 spp. 1997 - site not visited

GAC

A good mix of birds for training was encountered in the first five months of ‘96; Gt. Spotted Woodpecker and Jay were the highlights.

THE EMPLINS, GAMLINGAY (TL2452) Fifteenth Century house next to the village church. Swift colony of 20-22 nests. 1996 - 20 Swift pulli 1997 - 15 Swift pulli

GAE

Two poor years - probably the weather had something to do with it.

R. OUSE at GT. BARFORD (TL1351) Riverside Meadows where it is quite easy to catch a few Swans 1996 - 4 Mute Swan 1997 - nil

GBB

PARKSIDE, HOUGHTON REGIS (TL0324) Small private garden adjoining ancient hedgerow. 1996 - 1 Swift (released) 1997 - 1 Blue Tit

HRH

KETTLEDEAN FARM, nr. SHILLINGTON (TL1211) KDF Farm copse close to buildings in an arable setting. Has a potential for attracting finches. 1996 - 33 birds of 10 spp. 1997 - 8 birds of 5 spp.

WARREN VILLAS NR. (MANOR FARM) (TL1847) MAN Collection of former gravel pits in the Ivel Valley between Biggleswade and Sandy. They now form part of a Wildlife Trust reserve and a private fishery. 1996 - 313 birds of 5 spp. 1997 - 271 birds of 13 spp. 263 new Sand Martins and 43 Reed Buntings caught the first year with only 108 Sand Martins the second year but 131 new Reed Buntings. The site is usually only worked during Oct./Nov., Jan./Feb. and June/July each year. The ‘Recoveries’ section gives the notable recoveries/controls. PRIORY COUNTRY PARK (TL0749) PCP A landscaped, very popular, public park, in a large bend of the R. Great Ouse. Habitat consists of two large, mature lakes, several meadows, waterside scrub and maturing, deciduous plantations. A Constant Effort Site has been operated here in dry scrub since 1992. 1996 - 359 birds of 29 spp. 1997 - 594 birds of 29 spp. There were no visits in Sept./Oct. in ‘96 and similarly in Dec. ‘97. One Green and six Great Spotted Woodpeckers, 56 Blackbirds, 17 Redwings, 30 Sedge and 42 Reed Warblers, 48 Whitethroats, 26 Garden Warblers and 89 Blackcaps were caught over the two years - even though the weather was against both the birds and the ringers. New Willow Warbler numbers stayed in the twenties both years (catches were in the seventies back in ‘92 & ‘93) but 26 Bullfinches were ringed. As mentioned before, the birds that overshadowed all others were the controlled Cetti’s in January and the autumn Yellowbrowed.

SOUTH MILLS NR. (TL1550) SMI A small, restored sand and gravel pit in private ownership adjacent to the R. Ivel. 1996 - 221 birds of 24 spp. 1997 - 100 birds of 19 spp. The site is deteriorating due to the keeping of Pot-bellied pigs by the landowner which can severely hamper ringing sessions. Operated intermittently until September in ‘96 and then only Apr. to July the next year. 30 Sedge and 37 Reed Warblers were ringed in ‘96 but only 7 and 13 in ‘97. 44 Reed Buntings were caught, mainly at roost in ‘96. WATERLOO THORNS (TL1852) THO Part of a wartime airfield now largely covered in mature Hawthorn scrub. The site has been run as a Constant Effort Site since 1988 with few visits outside the CES calendar period (May to August) 1996 - 133 birds of 23 spp. 1997 - 607 birds of 33 spp. Only the first six visits of the CES were undertaken in 1996 and, therefore, the totals only contributed to the national adult survival indices. The other visits were missed when EN was moving to Bedford. The highest numbers caught were 19 Willow Warblers and 17 Robins. The following year numbers caught were much higher 42 Dunnocks, 32 Robins, 62 Whitethroats, 55 Blackcaps, 46 Willow Warblers, 45 Chaffinch and 23 new Bullfinches.

Note: All the Group’s ringing data is held on computer. The “non-standard” program was developed by RW in 1990 using a McDonnell-Douglas system called PRO-IV. The BTO also developed a DOS system known as B-RING. However, we find our system easier to use for inputting data; its one disadvantage is that we never properly developed the analysis part of the package. A MS-Windows compatible version of B-Ring is under development by a group of computer literate ringers and this is expected shortly. We will evaluate it when it is available and potentially switch to that system. This will mean “squirting” all the data we hold across to the newer programme. There will no longer be the need to prepare paper schedules for the Ringing Office since data for new birds - and also for retraps - can be sent in using a floppy disk. It will contain much more information about each bird, making for better analysis overall of our bird populations.

ANNUAL TOTALS FOR 1996-1997 (New birds ringed) Year Species Great Crested Grebe Leach’s Petrel Mute Swan Teal Mallard Pintail Shoveler Tufted Duck Sparrowhawk Kestrel Red-legged Partridge Water Rail Moorhen Coot Little Ringed Plover Ringed Plover Lapwing Dunlin Ruff Jack Snipe Snipe Woodcock Black-tailed Godwit Redshank Greenshank Green Sandpiper Common Sandpiper Turnstone Black-headed Gull Lesser Black-backed Gull Woodpigeon Collared Dove Turtle Dove Cuckoo Barn Owl Little Owl Tawny Owl Long-eared Owl Swift Kingfisher Green Woodpecker Great Spotted Woodpecker Lesser Spotted Woodpecker Skylark Sand Martin Swallow House Martin Tree Pipit Meadow Pipit Water Pipit Yellow Wagtail Grey Wagtail Pied Wagtail Wren Dunnock Robin Nightingale Redstart

Beds

1996 Cambs

1997 Beds

Cambs

1 72

1

3 3

1

1 1

20

15

6

1 5

4 265

108

20 35 48 6

2 7 5

2 49 72 62 4

GRAND TOTAL 3 1 320 15 12 1 1 2 46 8 1 4 24 4 19 72 132 8 1 21 114 1 1 37 1 1 7 1 1 2 28 15 8 13 12 5 3 2 493 83 18 25 4 23 871 852 734 2 111 1 33 9 116 1113 1443 1154 73 9

Year Species Whinchat Stonechat Wheatear Blackbird Fieldfare Song Thrush Redwing Mistle Thrush Grasshopper Warbler Sedge Warbler Reed Warbler Lesser Whitethroat Common Whitethroat Garden Warbler Blackcap Radde’s Warbler Wood Warbler Yellow-browed Warbler Chiffchaff Willow Warbler Goldcrest Firecrest Spotted Flycatcher Pied Flycatcher Long-tailed Tit Marsh Tit Willow Tit Coal Tit Blue Tit Great Tit Nuthatch Treecreeper Jay Magpie Rook Carrion Crow Starling House Sparrow Tree Sparrow Chaffinch Brambling Greenfinch Goldfinch Siskin Linnet Redpoll Bullfinch Yellowhammer Reed Bunting Corn Bunting County totals

Beds

1996 Cambs

1997 Beds

57

11

71

21 16

1

11 8

59 53 18 32 27 31

16 50

1 1 5

2

Cambs

5 3 7 2228 38 775 154 12 31 1638 1324 520 903 728 1466 1 1 1 566 2083 211 1 84 1 1287 29 44 76 4070 1874 2 133 19 12 1 2 534 119 16 1067 10 4111 278 31 246 142 862 324 2606 263

1 30 48 18 98 37 148

1 29 84 15

32 2 1 1 102 44 1 3 1 1

15 4

1

15 2 1

17 40

1 1

9 14

39

2

61

36 2

27

114 11

107 4 2 2 275 111

8 20 10 93

1 1

6 42 11 148

1 286

109

1 848

GRAND TOTAL

15

The grand total (of 108 species) covers the 16-year period from 1982 to 1997

=39 099

RECOVERIES & CONTROLS  Directions, distances and elapsed time are notified to us by the BTO. A recovery is where the bird is reported dead, not released, or released without its numbered ring; a control is where the bird is  Age (Euring notation) 1 pullus (nestling or chick incapable of flight) 2 fully grown, year of hatching quite unknown 3 hatched during calendar year of ringing 4 hatched before calendar year of ringing, but exact year unknown 5 hatched during previous calendar year 6 hatched before previous calendar year, but exact year unknown 7 definitely hatched two calendar years before ringing 8 hatched more than two calendar years before ringing Sex M sexed as male on plumage or cloaca F sexed as female on plumage, brood patch or cloaca J birds which are still in recognisable juvenile plumage = sexed on recovery  Manner of recovery X found dead XF found dying or freshly dead XL found long dead + shot , intentionally taken or killed by man S sick or injured - not known to have been released SR sick or injured, released with ring A alive and probably healthy - fate unknown V alive, caught & released with ring but not by ringer VV alive, ring or colour mark read in the field but not by ringer R caught and released by ringer RR alive, ring or colour mark read in field by ringer // condition on finding wholly unknown local = within 5km of the ringing site  This list is not exhaustive - it contains those records likely to be of interest to local ringers and land managers. Selection has been for the distance the bird has travelled, the time interval between trappings and the date or place of ringing or recovery. Mute Swan Z76453

Z81358

Z76471

Z76497

Z76454

Z49600

5 XF

Bedford Kettering, Norhants.

04-04-92 08-01-96

33km NNW, 1374days

1 R

Wallingford, Oxon. Bedford

23-07-93 31-03-96

77km NE, 982days

8M RR

South Mills, Blunham Hampton Court, Gtr.London

05-07-92 07-04-96

81km S, 1372days

6M S

Bedford Haddenham, Cambs.

23-08-92 23-10-96

47km ENE, 1522days

7F SR

Bedford Tring, Herts.

04-04-92 11-02-97

40km SSW, 1774days

6M RR

Bedford Priory CP, Bedford

09-02-85 31-12-97

local, 4740days

This last bird has dominated the Park and Fingers Lake in particular for at least eight years. It was given the honour of the first Darvic (orange 200). Unfortunately, it died shortly afterwards, in January 1998, of pneumonia, defending his third “wife”, a recent widow, in appalling weather.

We received reports of another 25 Swans that were found dead (12), sick (3) or had hit power cables (4), been kicked to death (1), taken by a dog (1), decapitated (1), had become iced in and died (2) or seen alive (1). None of these were more than 11km from the place of ringing. Wood Pigeon FA36268 4 R

South Mills, Blunham South Mills, Blunham

15-06-95 31-05-97

local, 716days

Not very often do we manage to retrap this species. A difficult one to catch, except by chance. Green Woodpecker DK81271 6M R Sand Martin K133901

K241208

K241065

J511555

K241754

J511739

K241324

K241318

J948910

J807645

K203054

Priory Country Park Priory CP

30-03-95 22-06-97

local, 815days

3J R

Wanlip GPs, Leics. Seddington

14-07-95 24-06-96

86km SE, 346days

4 R

Seddington Icklesham, Sussex

24-06-96 04-08-96

149km SSE, 41days

4 R

Seddington Buckden GPs, Cambs.

18-06-96 21-06-97

22km N, 368days

3 R

Priory CP, Bedford Baston Fen, Lincs.

23-08-95 30-06-97

65km N, 677days

3 R

Seddington Dunwich, Suffolk

08-07-97 17-07-97

131km E, 9days

3 R

Priory CP, Bedford Heath & Reach

06-09-95 18-07-97

26km SSW, 681days

3J R

Seddington Maxey GPs, Cambs.

16-07-96 03-08-97

61km N, 383days

4M R

Seddington Icklesham, Sussex

16-07-96 11-08-97

149km SSE, 391days

3 R =F

nr. Godmanchester, Cambs Seddington

10-07-96 08-07-97

25km SSW, 363 days

3 R =F

Icklesham, Sussex Seddington

17-08-95 28-06-97

149km NNW, 681 days

3 R =F

Icklesham, Sussex Seddington

18-08-96 08-07-97

149km NNW, 324 days

A good cross-section of recoveries that indicates the “unfaithful” nature of the species. Swallow J511626

J511639

3 R

Priory CP, Bedford Balby STW, Sth.Yorks

23-08-95 18-05-96

159km NNW, 269days

3 XF

Priory CP, Bedford Hatch, nr. Sandy

23-08-95 28-06-97

9km E, 675days

Our first Swallow recoveries since 1983-84 when EN tackled a small roost at Girtford GPs.

Dunnock H010857

J030583

J030044

3 R =M

Priory CP, Bedford Priory CP, Bedford

08-09-91 04-05-96

local, 1699days

3J R =M

Waterloo Thorns Waterloo Thorns

07-08-93 25-05-97

local, 1381days

4 R =F

Priory CP, Bedford Priory CP, Bedford

27-03-93 14-06-97

local, 1540days

02-06-93 29-05-97

local, 1457days

The three oldest birds for the current period. Robin J030192

3J R =M

Waterloo Thorns Waterloo Thorns

Our oldest so far is C266196 that used to spend the winter in/around EN’s Gamlingay garden. The final retrap interval was 1817 days (on 22-12-90). The national record is 3120 days. Nightingale J030992

5F R

Waterloo Thorns Priory CP, Bedford

30-04-94 15-06-96

10km W, 777days

This bird paired with a male (that was also first caught on 30-04-94 - but at Priory CP) with which it was retrapped. Blackbird RH42274

RH42479

3M R

Chalton STW Chalton STW

25-11-90 02-06-96

local, 2016days

6M R

Priory CP, Bedford Priory CP, Bedford

16-03-91 27-04-96

local, 1869days

These are our oldest Blackbirds at the present time. At seven years (or older) the second bird has reached a good age for a Blackbird. Many die young around two-three years old; the national record is almost 15 years. Song Thrush RS29794

RS59015

RV56085

3J R =M

Priory CP, Bedford Priory CP, Bedford

18-09-94 21-03-97

local, 914days

5F R

Waterloo Thorns Waterloo Thorns

25-06-94 25-05-97

local, 1064days

3J R =M

Waterloo Thorns Waterloo Thorns

10-06-90 29-05-97

local, 2545days

Song Thrush mortality in their first autumn and winter is high. This is a major contribution to the species recent decline. It is believed to be caused by lack of suitable foods e.g. slugs and snails. Obviously, some of the youngsters are making it - despite adverse habitat conditions elsewhere. Cetti’s Warbler K838113 2F R

Beachy Head, Sussex Priory CP, Bedford

19-10-96 25-01-97

163km NNW, 98days

This bird was trapped eleven days after the first (un-ringed) Cetti’s appeared at the site.

Sedge Warbler H460589 4M R H460357 J272898

3J R 3J R

Reed Warbler F717450 5M R

Priory CP, Bedford Priory CP, Bedford

25-07-92 12-05-96

Priory CP, Bedford Priory CP, Bedford South Mills, Blunham Godmanchester , Cambs

21-06-92 25-05-96 02-07-95 21-07-96

Houghton Regis ChP Wilstone Res. Tring, Herts.

15-07-90 12-05-96

local, 1378days

local, 1434days 25km NNE, 385days

16km SW, 2128days

An update on the record in the last report; seven years old is quite special. H355680

H872910

5M R =M

South Mills, Blunham South Mills, Blunham

21-05-92 22-06-96

local, 1493days

5M R

Houghton Regis ChP Marsworth Res. Tring, Herts

03-06-93 15-06-97

14km SW, 1473days

Remember that vandals burned the reed bed in the Chalk Pit in 1996 Whitethroat J600042

6M R

Waterloo Thorns Waterloo Thorns

14-05-94 19-07-97

local, 1161days

This is our longest. The bird was at least 6 years old. In the majority of cases, the males seem to return for just two or three years (before they are dead?). Females are not very site faithful. Garden Warbler H460650 3J R =M H460268

H871869

J030147

J921004

H460497

Priory CP, Bedford Priory CP, Bedford

28-07-92 12-05-96

local, 1384days

5M R

Priory CP, Bedford Priory CP, Bedford

10-05-92 25-05-96

local, 1476days

3J R =F

South Mills, Blunham South Mills, Blunham

01-07-93 16-06-96

local, 1081days

4F R

Waterloo Thorns Waterloo Thorns

14-05-93 23-06-96

local, 1136days

4 R

Linford Lakes, Bucks Priory CP, Bedford

10-05-95 03-05-97

25km ENE, 724 days

3J R =M

Priory CP, Bedford Priory CP, Bedford

17-07-92 30-05-97

local, 1778days

A selection of our older birds returning to breeding sites. H871869 is included since it appears to be a female returning to nest at its natal site. This is not very common at all in warblers. E238223 is still our oldest.

Blackcap J271003

3J R =M

Bidwell, Houghton Regis Windsor Great Pond, Berks.

18-07-93 06-05-96

54km S, 1023days

This is an update on the previous record in the last report. H460700

3J R =M

Waterloo Thorns Heck Dale, Dalby, Nth.Yorks

02-08-92 13-07-97

235km N, 1806days

Our oldest Blackcap to date, now “living up north”. J600993

Chiffchaff 9S3447

3J R =M

Priory CP, Bedford Icklesham, Sussex

09-08-97 07-09-97

157km SSE, 29days

3J R =M

Hitchin STW, Herts Priory CP, Bedford

18-06-95 22-06-96

21km NNw. 370days

Rutland Water, Leics Waterloo Thorns

01-05-94 06-05-96

64km SSE, 736days

3JM R

Priory CP, Bedford Priory CP, Bedford

17-07-92 12-05-96

local, 1395days

3JM R R

South Mills, Blunham Priory CP, Bedford Priory CP, Bedford

03-07-94 08-07-95 25-05-96

8km W, 692days

4M R

Waterloo Thorns Waterloo Thorns

28-07-91 04-05-97

local, 2107days

Willow Warbler 5W7152 4 R 5F8858

3S8846

5T8279

Now our oldest “Willy” but 1500 days short of the BTO’s record. Trapped every year except ‘96. Long-tailed Tit 3S8660 2 R =F 8S1188

3L4926

Blue Tit H460229

H872893

J271049

J030252

Waterloo Thorns Waterloo Thorns

02-06-93 01-06-96

local, 1095days

2 R =F

Chalton STW Chalton STW

27-12-93 08-02-97

local, 1138days

2 R =M

Bellows Mill, Eaton Bray Chalton STW

14-12-96 22-04-97

9km NE, 129days

5F R

Priory CP, Bedford Priory CP, Bedford

03-05-92 04-12-96

local, 1676days

5F R

Chalton STW Chalton STW

01-06-93 06-03-97

local, 1374days

3F R

Chalton STW Chalton STW

31-08-93 12-08-97

local, 1442days

3JM R

Waterloo Thorns Waterloo Thorns

19-06-93 16-08-97

local, 1519days

H460229 is the ‘oldest’ this period.

Great Tit H010733

3JM R

Priory CP, Bedford Priory CP, Bedford

24-08-91 12-04-97

local, 2058days

Expect to hear more of this large male with an 81mm wing chord! Chaffinch J030060

5M R

Waterloo Thorns Waterloo Thorns

04-04-93 02-08-97

local, 1581days

This is our oldest Chaffinch so far. Greenfinch VN20408

VJ74572

5M R

Gamlingay Cinques Landguard BO, Suffolk

20-01-96 08-04-96

107km ESE, 79days

5M R

Priory CP, Bedford Priory CP, Bedford

21-04-91 04-05-96

local, 1840days

Most likely, VN20408 was a 'continental' bird returning "home", using the short, southern North Sea crossing. VJ74572 is our oldest Greenfinch to date. Bullfinch J600284

J600733

3J R =M

Priory CP, Bedford Priory CP, Bedford

16-07-94 26-08-96

local, 771days

3J R =F

Priory CP, Bedford Priory CP, Bedford

26-07-95 09-08-97

local, 744days

nr. Pymore, Cambs Seddington

10-10-95 04-02-96

52km SW, 117days

3JM R

South Mills, Blunham South Mills, Blunham

20-07-92 14-04-96

local, 1364days

5M R

South Mills, Blunham South Mills, Blunham

27-01-93 19-05-96

local, 1205days

3F R

South Mills, Blunham South Mills, Blunham

27-11-93 13-04-97

local, 1232days

Reed Bunting K428168 3F R H355950

H872366

J271920

SPECIE’S REPORTS TEN YEAR COMPARISON OF PERCENTAGE JUVENILES CAUGHT IN BEDFORDSHIRE Because of the ups and downs of catching, it posed the question whether the number of juveniles caught over a period bore any relationship to one another. Six species were chosen: Robin (which nests rather early), Great Tit (fledging young in late April), Blue Tit (fledging early May), Willow Warbler (mainly double brooded spread through May & June), Blackcap (June and July) and Reed Warbler (that has fledged young in July & August). These six species give a good spread over the breeding season. Any peaks or troughs should indicate that poor weather had affected their breeding attempts either by “washing out” the nest at the egg stage or by suppressing the food supply during fledging and immediately after. If all the species reach a peak or trough together, then it might indicate that it was a particularly good or poor year for finding prey items across the board. Below are the six charts for the period 1988 to 1997. All data was taken from the Group’s records for its Bedfordshire sites only.

% of catch Robin 100.00%

75.00%

50.00% 88

89

90

91

92

93

year Series 1 G reat T it 100.00% 75.00% 50.00% 25.00%

BlueTit 100.00%

75.00%

50.00%

25.00% Series 1

94

95

96

97

WillowWarbler 75.00%

50.00%

25.00%

0.00% Series 1

Series 1 25.00%

50.00%

75.00%

100.00% Blackcap

ReedW arbler 75.00%

50.00%

25.00% Series1

Robin We have always expected to catch a high percentage of '3s' compared to adults; the level on all sites has remained high, around 70-75% of the total number. Why this is higher than other species has never really been understood. From the graph, this "base level" can clearly be seen. There are peaks in 1989 and 1993. In both these years, the first six-month period had average rainfall (ca. 250-300 mm) and the temperatures were a little above average for the time of year. In 1993, the autumn turned relatively cold and spring 1994 turned cold and wet after a promising start. 1994 gave the lowest percentage ever and the dip between the two years is pronounced on the graph. It is also an indication of the weather having a deleterious affect on that season's breeding success. The steep trough shown in 1996 on all the other graphs does not occur on that of the Robin; perhaps this is because the species is an early nester and benefited from the best of the weather when rearing its young.

Generally, it seems that the English weather suits both the Robin and its food supply, enabling it to successfully rear many young in a normal year. The species is highly territorial and surplus (immature) birds must move away or quickly perish in autumn (called intraspecific competition). Following a severe winter, something we have not seen for a while, the Robin population recovers quickly, provided that such a winter is not followed by a cold spring. Great Tit The anticipated percentage of juveniles caught during a year is around 60%. However, the specie's productivity is subject to severe ups and downs and this is very much dependent on the food available to the nestlings. If the weather precludes normal, seasonal tree growth then the numbers of defoliating caterpillars will be fewer and smaller in size and the female Great Tit and her young less well fed, i.e. less fit. The warmer the weather at nesting time, the higher the survival of the young. Just as in the Robin, there are peaks in 1989 and 1993 with a lesser peak in 1995. Productivity slumped to half that of "normal" in 1990, 1994 and 1996 and to a lesser extent in 1997. This can almost certainly be put down to the lower than average temperatures in May with many daily maximum temperatures in the mid-'teens Celsius during the "poor" years instead of the low twenties that we would expect. Blue Tit As a rule, we expect catches to average two juveniles to every adult bird (60-70%) once the young have fledged. The graph follows that of the Great Tit above but the variations are less pronounced. As the Blue Tit nests just that little bit later than the Great Tit, it usually benefits from slightly better weather (i.e. warmer days). It also has a larger brood that may help dampen any variation. The same weather patterns that affected its larger cousin above apply. As Blue Tits out number Great Tits by 5:3 in the winter period, the larger population may also help to smooth the graph. Willow Warbler The normally expected percentage of '3Js' on our sites has been about 60% of the total Willow Warblers caught. Some ringers in other parts of the country trap as many as 75% of their totals as juveniles. In 1989, this species was the only one to show a decrease in juvenile productivity; we also trapped 50% fewer Willow Warblers that year than in the previous year. There followed four steady years before another"drop off" occurred. From 1994 the trend is downwards; 1995, a long, dry and warm summer, was the exception. 1996 in contrast exceptionally dry from April through to August, with the added complication of some severe thunderstorms at the beginning and end of June. This weather pattern is likely to have affected this specie more than most since it nests in grass tussocks on the ground and feeds in open scrub and woodland where the parching of the habitat was most apparent. 1996 was, therefore, a disastrous year for all the mainstream nesters that utilise the scrub habitat component. Blackcap This graph is different from the others in that it shows a climb to a peak in 1991 followed by a gradual decline until the "bad year", 1996, since when there has been a good recovery. The numbers of young Blackcaps that we catch is very much dependant on the numbers of migrants coming through in the middle of September. The large majority of our "native" youngsters leave at the end of August or the beginning of September. Blackcap numbers have been increasing nationally throughout the 'nineties. The species also tends to nest in heavier cover than the Willow Warbler and this habitat is, to some extent, better protected from the vagaries of the wind, rain and most important of all, evaporation from the soil and desiccation of the habitat. It suffered like all the rest in 1996 - but to what extent it is not possible to say here because very little ringing took place by the group during that particular autumn migration. Reed Warbler And now for something completely different (with apologies to Monty Python). The dominant aspect here is the biennial seesaw effect. We have noticed this before and remarked upon it. Why this should happen in the Reed Warbler (it also is apparent with Long-tailed Tits) we simply do not understand. Is it something to do with the growth of the Phragmites and Typha? Or is it to do with the inexperience of last year's young to make a proper go of it? Do they need a learning curve before they produce lots of young themselves? 1993 shows a small anomaly in the general pattern. July that year was noted as being "cool and wet"; this may account for the lower percentage of young that year.

These six species were chosen not only because their individual breeding seasons are spread throughout the spring and summer but also because they are trapped in good numbers (or have been) over the years. They also represent a cross-section of different nesting strategies and differing habitats. None of the above is very scientific - we leave that to the staff at the BTO - but, like the rest of all our reports, we try to make it an enjoyable and thought provoking read. [Author: E C Newman]

JUVENILE WHITETHROATS Updated plot of the number of juvenile Whitethroats caught at Waterloo Thorns from 1988 to 1997 (excludes 1996) during CES visits 5-12 compared to the mean maximum temperatures recorded during th th the period 20 May – 30 June inclusive.

Juvenile Whitethroats Nos. caught V mean max. temp. 24 23 mean max. temp.

22 21 20 19 18 17 16 15 15

20

25

30

35

40

45

50

55

60

numbers caught CES visits 5-12 Series 1

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

Mean max. air temp C

18.7

21.4

19.1

17.9

22.7

20.7

20.1

20.4

21.5

21.1

No. of juveniles (V5-12)

24

34

35

20

55

42

45

18

n.d.

38

o

MEMBERSHIP The Group is registered with the British Trust for Ornithology (ringing group 9147) which administers the British and Irish Ringing Schemes. The Group is a corporate member of the Bedfordshire Natural History Society. At the end of the period the following were subscribing members of IRG: Dr E Brindley, N R Finan, E C Newman, A Proud, J M Reed, S Spick and R Wooding. E Newman and S Spick are Full Trainers and members of the Trainers Panel.

ACKNOWLEDGEMENTS We would like to thank the following for permission to ring on their land: Anglian Water Services, Bedford Borough Council, The Wildlife Trust for Bedfordshire, Mr & Mrs P Gorton, Mr & Mrs G Hill, A Pym Esq., South Mills Leisure Club. (+KDF) We would also like to thank the Bedfordshire Natural History Society for purchasing replacements nets for the two ongoing Constant Effort Sites.

Articles in previous Reports: No.1 (1990-91) Waders ringed in the Ivel Valley 1983-91 Swift pulli ringed and brood sizes at Gamlingay 1983-91 Whitethroats ringed at the Thorns (CES data) 1988-91 Reed Bunting biometrics No. 2 (1992-93)

Whitethroat productivity in relation to temperatures Warbler passage at Priory CP in autumn Recovery maps

No.3 (1994-95)

Initial data from a Nightingale study at the Thorns 1988-95

Address for correspondence: *REMOVED.

Report compiled August 2000 Published December 2001

Copyright reserved Ivel Ringing Group September 2000