An Amazing Sedge Warbler

A clear calm interval on Saturday morning gave us the opportunity to visit the Spring ride at Leighton Moss RSPB Reserve. The first round of our six nets produced a good variety, including a Cetti's warbler and a Nuthatch and four Sedge Warblers these were weighed  and  none showed any sign of fat. The average weight was 10.7 grams. The next round produced two more  Sedge Warblers one at 10.2 with a fat score of 1. Kevin extracted the other and was amazed  when he examined it , its body was completely covered in fat including the breast and he gave it a fat score of 8. We all guessed at its weight and the highest suggestion was 16 so we were all amazed when it came in at 19.3.grams. When I entered this weight on IPMR it came up with a warning that the usual highest weight was 17.9. So quite an intriguing bird

According to the migration Atlas Sedge Warblers mainly fatten up for their journey across to France along the English south coast or the South Wales coast. We have ringed as a group just over 14,000 Sedge Warblers so  just about impossible to search through these  but we only occasionally get birds above 13 grams. However a search of September catches revealed one  at 15 grams in late September and this appears to be the heaviest we have recorded up to now.

It is thought that Sedge Warblers fatten up on Plum/reed aphids which is abundant in many parts of the reed bed this year. But it is still amazing that this bird should accumulate so much fat especially when only one of the 89 other  birds caught this year so far, exceeded 13 grams and that by .1 of a gram.
John

Knot in odd places

My short working description of the purpose of the ringing scheme is 'Finding out what normal birds normally do rather than what rare birds rarely do' and similarly most BTO surveys are about 'what's there, what's not there but not what's rare'.  Just occasionally odd things do happen and they can be interesting too.  They're often what sparks an interest that lasts a lifetime.

My interest in Knot began one evening in late September 1999 when I handled my first Knot at Wolferton, Norfolk.  What made this juvenile Knot interesting was it had a metal ring above the knee and by the time I had read as far as 'Buda' on the ring it was in someone else's hand.  For me this is a moment that I'll never forget and also a lesson I pass on to everyone starting out wader ringing - Always check above the knee for rings.  It would have been easy to miss, particularly in the dark at the end of a long week of wader ringing.

The 'Bird ringing in Britain and Ireland in 2001' report mentions this bird:

HGB KX5227 is unprecedented. Few Knot are caught in Hungary each year, only 20 were ringed between 1985 and 1998 (Varga pers comm), and this bird was one of only two Knot, both juveniles, which were caught in walk-in traps on autumn passage in 1999. Just 10 days later the bird was mistnetted on the Wash. This will have been a canutus Knot from the Siberian population on passage to the wintering grounds in Africa. Given the number of Knot passing through Hungary and the scarcity of canutus now visiting Britain (Boyd & Piersma 2001), this recovery is quite amazing. SVS 4294422 is the eighth Swedish-ringed Knot to be reported in Britain & Ireland.

Since this exceptional record another Hungarian ringed Knot has been caught in Porsangerfjord, Norway in spring suggesting that at least some of the Knot reaching Hungary are islandica. I would guess they have overshot the west coast of Norway on the way south, gone down the east coast of Sweden and through central Europe however this is pure speculation.

Broadly speaking all the sightings of the Formby Knot have been as we expected with many in Iceland in spring, the odd one in Norway both in spring and autumn, a couple of the Netherlands, many in Scotland and Ireland but without exception on the coast.  This weekend Twitter sprung into life with a photograph of a flagged bird at Blithfield reservoir in Staffordshire.  Sadly the Knot was too far to read the flag so I thought we would just have a cohort record rather than an individual.  Luckily another photographer had a closer photograph and we now know this bird's identity.  Up until this record this Knot had done what we expected - stopped over in Iceland in May after spending at least some of the winter on the Sefton coast.  This is the first recovery of a Knot in Staffordshire.

With the big tides this weekend I'm sure a lot more sightings will be made and maybe this one will have reappeared in a more expected place.

How Long Do Birds Live?

With poor ringing weather I spent sometime updating our longevity records for our most regularly ringed species.I find it fascinating how this varies from species to species. Not only did I record the oldest bird but all birds surviving five years and above after ringing.

The most amazing species is Reed Warbler with a record of 9 years and 314 days after ringing and with 44 records over five years. Compare this with Sedge Warbler with a record of only 5 years and 51 days and  the only one making 5 years. Granted we have ringed 17, 234  Reed Warblers almost 7000 more than Sedge Warblers and the retrap rate for Reed Warblers is 23% compared to 12% in Sedge Warblers. The high retrap rate suggests we are mainly catching a breeding population of Reed Warblers although recoveries show a small number passing through our sites from the few small colonies to the north with 22 in Cumbria (mainly at nearby Helton Tarn) but only one in Scotland. Sedge Warblers by contrast have  ten spread around Scotland and 11 from Cumbria. So in the case of Sedge Warblers quite a proportion are from a  transient  migratory population  where the chance of retrapping in following years is low  One wonders why there is such a difference between these closely related species? Is it conditions in the wintering areas in Africa or different migration or breeding  strategies?

Of the other warblers the Lesser Whitethroat  record is  5 years and 19 days with another one at five years with only 844 ringed. Next best is Willow Warbler with four at five years from 10964 ringed,  but like Sedge Warblers a good number of the birds caught are migrating through our area with 14 reports from Scotland and four from Cumbria.

Bearded Tits with 17 birds five plus years and a national record of 7 years 93 days are also exceptional. These are the results of an intensive RAS study based on 2458 new birds and 7618 colour ring sightings or retraps.

Of the resident species Chaffinch (oldest 9 years and 246 days) has 17 records of five years plus, as does Blue Tit (oldest 8 years and 15 days) but  we have handled over 31000 more Blue Tit than Chaffinch! Of the other tits Marsh Tit is also outstanding with a record of 8 years 220 days and four over five years plus from only 725 handled. Long-tailed Tits(oldest 7years 285days) has 6 over 5 years from 3169 handlings.
 The table below details my findings with details  of numbers ringed, retraps/sightings. Numbers of birds  above 5 years and for comparison the national longevity record.


John

Table 1 Longevity Records for Most Ringed Species 1999-July 2018

Species	New ringed	Retraps  Etc	Oldest	9+ years	8	7	6	5	National
Sand Martin	17076	3334	6 Y 19D				1	6	7y 9m 1d
Swallow	23076	130	3Y 253 D						11y 1m11d
Wren	3467	1162	5Y 290d					1	7y3m6d
Dunnock	3130	1632	9Y 285D	1		1	4	2	11y3m7d
Robin	5203	1715	7Y 95 D			1	1	5	8y4m30d
Great S Wood	301	158	5y 161 D					1	11y5m2d
Blackbird	3494	1239	8Y 155 D		1		6	9	14y9m15d
Song Thrush	1023	152	6Y242 D				2	2	11y8d
Redstart	1363	21	4Y 80 D						8 y8d
Grey Wagtail	1003	78	4 Y70 D						7y1d
Sedge Warbler	10752	1463	5 Y 32 D					1	8y8m8d
Reed Warbler	17234	5325	9 Y314 D	2	2	8	11	21	12y11m21d
Blackcap	3154	437	4 Y 43 D						10y8m15d
Whitethroat	2450	361	4Y 84 D						7y9m5d
L.Whitethroat	844	180	5 y 19 D					2	9y2d
Willow Warbler	10964	774	5Y 337 D					4	10y11m18d
Chiffchaff	3783	400	2 Y 332 D						7Y7M24D
Cetti’s Warbler	65	61	3 Y 344 D						9Y 3M28D
Goldcrest	5184	728	2 Y113 D						5Y1M12D
Pied Flycatcher	9135	925	6 Y 10D				1	3	9Y7D
Bearded Tit	2458	7618	7 Y93D			2	4	13	7Y3M
Long-tailed Tit	3169	1850	7Y 285 D			1	1	4	8Y11M
Blue Tit	31155	8644	8 Y 15 D		1	5	3	8	10Y3M10D
Great Tit	13709	3922	13Y 329D	1			1	2	13Y11M5D
Coal Tit	4282	2975	7 Y21D			1	3	1	9Y2M25D
Marsh Tit	455	270	8Y 220 D		1	1		2	11Y3M
Nuthatch	976	2467	4Y 230D						10Y11M3D
Treecreeper	494	137	4Y 364 D						8Y18D
House Sparrow	1062	67	5Y 327 D					2	12Y12D
Chaffinch	7044	975	9 Y 246 D	2	3	3	3	6	13Y11M26D
Greenfinch	8862	1105	9 Y	1		1	1	2	12Y8M26D
Goldfinch	6675	1213	5 Y 15 D					1	10Y2D
Siskin	3306	93	3 Y 363 D						8Y1M27D6Y4M2
Twite	1227	1194	3 Y 363 D						6Y4M24D
Lesser Redpoll	2651	1031	4Y 333D						6Y10M11D
Bullfinch	956	488	6 Y361 D				1	1	9Y2M9D
Reed Bunting	3440	433	7 Y 355 D			1		1	9Y4M18D