25/02/12 - More Shelduck...more old friends!

Another good day (Friday 24^th) with a catch of 13 new and 10 re-trap Shelduck in one of the traps (along with 10 new Mallard and a Coot). 

The next Webs count in March will tell us how many Shelduck are present  throughout the valley but 90 were counted by a local farmer roosting on his pond one evening last week - probably a good indication that it’s around the 100 mark at the moment. A quick look at the figures caught this year reveal 47 new birds ringed so far, with 13 re-traps from previous years and the one control - a total of 61 different birds handled so far this year. 

It’s nice to have a good sample of the population marked and once again shows a high degree of turnover of breeding birds from one season to the next, especially as we ringed 59 birds out of the population last year. Of the 11 re-traps from previous years, 6 were originally caught in 2011 and 2 from 2010, 2006 and 2005. So clearly some of the birds are site faithful (certainly for one or two years and some even longer). Smaller numbers of birds, mainly pulli (with a higher mortality rate), were ringed in 2007-2009 which may account for the ‘non-appearance’ of birds from those years. 

Although the whole reserve covers over 1000 hectares, which stretches some 10 Km along the River Derwent and the Pocklington Canal corridors, its often amazing how site specific some birds are. A male Mallard caught at Bank Island in a whoosh net catch yesterday was originally ringed in the same whoosh net area (10 x 10m) at Bank Island on 30/05/10. Nice to know he’s dodged the lead shot and wintering Peregrines for two winters! However, topping that was GN12614, a Mallard caught and ringed at Wheldrake on 28/06/99 and re-caught today at North Duffield Carrs. That’s nearly 13 years since ringing and makes it atleast 14 years old. Interesting that it’s not been re-caught since, so you have to wonder where it’s been since we last saw it. It’s certainly a good age for such a popular quarry species, the longevity record from the BTO ringing in the UK is 20 years and 5 months. 

Continuing the Mallard theme, Mike & Craig had a control female Mallard - GR37501 today (one ringed somewhere else by another ringer). This is the first time we've controlled a Mallard in the Lower Derwent Valley, so it will be most interesting to see where it's come from....

20/02/12 - A new surprise...

Things have been ticking over in the last few days with one or two new birds being caught each day, mainly Shelduck, 34 new birds and 10 different re-traps from previous years have now been caught during 2012.

On arriving to check the trap today there were two Shelduck up on the grain in the whoosh net area - with a similar sized dark bird just behind them. A quick double take followed by an instant fire of the net added a fine first winter Dark-bellied Brent Goose onto the LDV ringing totals. The species is rather scarce in the valley, being less than annual with 15 records in the last 35 years. Occurrences can be rather sporadic but there is a trend to fall largely between January - March, but birds tend to move on quickly and seldom linger for more than a day. All in all a big surprise, and the 150^th species to be ringed in the valley (not bad for an inland site!). 

Also on a scarce goose theme - Egyptian Geese have been increasing in the valley over recent years. There were five records between the first in 1979 and 2002, with another 5 between 2003 - 2009. A pair arrived in the valley in early March 2010 and the male found this way into a whoosh net area on 25/03/10. They attempted breeding (but appeared to fail) in 2010 and again (along with a second pair) which attempted but failed in 2011. They have turned up again over the last few days as the photo below from Hagg Bridge shows. It’s obviously of value to have at least one of the birds ringed so we can keep tabs on what’s happening with them, especially as it may be the start of colonising the valley.

15/02/12 - 'Shelducking'

Following the successful hard weather catching of recent weeks, numbers have now started to decrease as both the ice released its grip on the valley and melt water from the North York Moors caused birds to spread out around the valley and revert to natural food sources. Still, we can’t complain as it was good whilst it lasted and we certainly made the most of it.

However, February is typically the start of Shelduck ringing in the valley, and with Shelduck numbers starting to increase and now beginning to use some of the trapping areas it’s looking promising. Today saw the best catch of the year so far for the species with 9 new birds and four re-traps. It’s always nice to catch a mix of new birds and ‘old friends’ so it was really good to see GN81934 (black darvic FL) who was originally ringed in the same spot on 04/02/05, seven years and a week earlier! 

The following photos were taken to explain how we’re ageing Shelduck. The bird in the photograph below is a 7 (which means it’s definitely two years old and so it hatched during 2010). Notice the white tips to the secondaries and some of the primaries, but otherwise it’s an adult looking wing. It’s possible that not all birds of this age can be confidently aged to this level.

 

The Shelduck in the photograph below is an example of a bird that might be a 7 (definitely hatched two years ago) because it’s still got white on the tips of the secondaries but no white on the primaries - and so it was aged as a 6 (hatched at least 2 years ago) as we can’t be sure it was hatched in 2010.

The bird below is a 6 (adult) there’s no grey on the coverts and no white tips to the secondaries and the wing is bright and colourful. Birds like this one may be 3+ years old (which would make it an 8), but again we’re not sure these could be recorded with confidence. There is still a lot to be learned about ageing waterfowl!

Until Shelduck are atleast two years old they can't be sexed, from then on it is based on knob size and shape/colour of the bill nail. Some adult males have large prominent knobs, the one in the photograph below is on the small size, and males have a well defined 'v' nail. Female birds show a blue coloured tip with a less defined nail, and they lack the knob of the males.  

Male

Female

Whilst at North Duffield, Steve managed a couple of nice photographs of the local Barn Owls, they were out and about day flying this afternoon, enjoying the milder conditions and disappearing snow cover.

Before we went out this morning the net at the base was open for a few hours whilst we were doing hide repairs, a nice small catch of 14 birds, made up mainly of Greenfinch (8).

Greenfinch (juvenile male)

13/02/12 - Breaking records

As of today we have ringed 203 ducks this month making it the best February to date after 174 in February 2004 (and we are only half way through the month). That’s 359 ducks during 2012, including exactly 220 Teal, which represents between 10-16% of the UK annual ringing totals over the last 5 years. It should hopefully generate a few recoveries in the years to come...

Although most of the effort has been focused upon wildfowl ringing, the net at the base feeding station has been open for a couple of hours during the last week in-between other jobs around the base. This accounted for 30 new birds with suggestions of an influx of un-ringed Robins, Dunnocks and Blackbirds mirroring other local sites. Three Reed Buntings were nice at this site whilst a Fieldfare was the first of the year to be caught. Up to 6 Short-Eared Owls were present in the southern half of the valley on Saturday (11^th) whilst 2 Kingfishers are also still present on the River Derwent at North Duffield Carrs. 

Following on from Saturday it was a similar picture yesterday (but slightly warmer one) with 6 new Wigeon, 4 Teal, 2 Mallard and a Moorhen, whilst amongst the re-traps was another different Shelduck, originally ringed in the valley in June 2010.

Today (Monday 13^th) once again delivered another huge catch - 46 birds in the trap with another 26 new: 20 Teal, 5 Wigeon and 1 Mallard, with re-traps including a Moorhen, Coot and Pintail - 6 species of wildfowl.

11/02/12 - Back on track, in style!

At the end of the last blog post (Wednesday 8^th) we mentioned how the ice had finally beaten us and blocked the funnels. This was extremely frustrating given that the traps had been so successful in catching during the present conditions. A bit of head scratching and a quick dash to B&Q saw us back at the trap in the evening with a hammer and blow torch to melt away the ice from around the trap entrances.

Obviously the ducks had been kept out the trap for 36 hours and we had put additional ‘free’ food around the outside of the trap to encourage them to keep the water around the trap ice-free. The result was just two ducks on Thursday morning, but for Dan Lombard who joined us from the coast for some duck experience, a superb adult male Pintail and drake Wigeon - a nice way to start your duck ringing! Quality not quantity!

The following morning (Friday 10^th) we were back on track making the most of the conditions once again - with another great catch of 29 new Teal and 4 new Wigeon. Temperatures then plummeted reaching -10 during the night of the 10^th/11^th, this greatly reduced the size of the open water on the Top Pond and also increased the ice build up on the entrances to the trap again. However, it was so cold that even the River Derwent started to freeze (see below) with a constant movement of ‘ice flows’ downstream. This forced larger numbers of ducks onto the Top Pond and despite the ice build up, another 16 new birds were ringed - 12 Teal and 4 Wigeon. 

 

It’s been interesting to watch the weights and wing lengths of the birds involved this week - after a sharp fall in weights last week as the cold spell kicked in, this week weights have gone back up to around the average despite the prolonged freeze - interestingly wing lengths of the birds have also gone up with some very long winged Teal (up to 204mm), Mallard (292mm) and Wigeon (up to 285mm) - have our wintering birds moved out and been replaced by continental birds moving west...??