01/05/14 - Whimbrel'ing on Wheldrake

On Tuesday staff and volunteers from the LDV Team spent the night on Wheldrake Ings catching Whimbrel – and with 109 birds coming into roost the previous night things were looking good. The nets were positioned in three different areas which we believed the birds may pass through on route in to the roost. At 2010hrs the first birds, a group of four, flew into Swantail Ings and by 2050hrs a total of 58 were present. A final flock of 51 (which had roosted and come in as a single flock the previous night) flew in around 2100hrs, another hour’s wait for complete darkness then we could start doing the rounds. Over the course of the evening and into the early hours many miles (or what felt like!) were walked in chest waders, through deep water, thick mud and long vegetation but it was all worth it for a catch of 8 Whimbrel, 1 Lapwing and 1 Mallard.

One of the newly c/r Whimbrel for 2014

 

Out of the 8 Whimbrel 6 were new with 2 from previous years – one from 2009 and one from 2010. With the difficulty of reading colour-rings in the field this year it was most pleasing to catch these two birds. Full details are listed below:

EL49894: Yellow//Green Yellow 

2009 - Ringed on 29^th April at the Wheldrake roost

2010 - Re-caught at the Wheldrake roost on 26^th April

2012 - Sighted on 4^th May at Nosterfield Gravel Pits, North Yorkshire

2013 - Re-sighted on 22^nd April at the favoured feeding fields in Storwood

2014 - Re-caught at the Wheldrake roost on the 29^th April

EL49985: 

2010 - Ringed on 2^nd May at the Wheldrake roost

2014 - Re-caught at the Wheldrake roost on 29^th April

Since the initial ringing date the oldest bird here (EL49894) ringed in 2009 has travelled at least 80,000 Km on its many journeys between the Lower Derwent Valley to Iceland (to the breeding grounds between May to August) and then on to the West African wintering grounds from September to March before returning once again in the spring to the Wheldrake roost.

As mentioned previously we’ve struggled so far this year to read colour-rings from birds in the field during the day, which over the years is how we’ve managed to build up such a great set of data – with to date over 195 sightings of 53 colour-ringed Whimbrel (out of 106 which is the total number of birds colour-ringed since the start of the project in 2004).

Interestingly this year we also haven’t seen the birds as frequently in their favoured feeding fields – which is presumably down to the fact that the fields are so dry (and with a good growing season, the vegetation is too long to favour them) so they seem to be struggling to feed and find available earthworms and leather jackets (cranefly larve) - their favoured food. In fact the only feeding birds found this year have been unusually found on newly ploughed fields which have presumably offered them an easy, but temporary feeding opportunity. This was then confirmed at the roost as out of the 8 birds that were caught the weights ranged from 385 being the lightest with 425 being the heaviest. The average weight/what we would expect at this time of year and at this stage in the valley is around 450 to 500 grams so about 100 grams down on what might be expected. Whilst that doesn’t sound like much it is about 15-20% of their body weight. These individual birds are likely to only be here for another 8 days or so, and during this time they feed up on their main prey items of worms and cranefly larve, almost doubling their body weight before setting off on their 24 hour non-stop journey to Iceland, and with such a long journey before them it’s so important that they manage to feed up during their short stay in the valley.

During the evening of the roost we were treated to views of Greenshank and Little Ringed Plover, along with listening to Snipe drumming. Whilst walking the fields we also came across three clutches of Lapwing eggs (all of 4 eggs) and a Coot incubating 13 eggs. A late passage Jack Snipe was seen twice, a Roe Deer was heard barking on several occasions and a male Barn Owl was quartering over the site during the evening.