A Tale of Two Birdies

October 17th 2013

Article originally published in the Assynt News during October 2013

A Tale of Two Birdies

It was a good time for one; it was a bad time for the other!

This story is not about revolution but more about revelation; more specifically about what a few small rings on the legs of two birds can reveal.

The first bird, a Siskin, was discovered by Beccy Garvey the gardener at Ardvar on 21st June. It was, sadly, dead, most probably as a result of a Sparrowhawk taking advantage of a moment’s lapse in concentration by the Siskin.

Beccy firstly was fortunate enough to find such a small green bird but she then had the foresight to take a closer look and so noticed that it had a metal ring on one of its legs.

These metal rings are put on birds’ legs by highly trained volunteers and professionals and ringing schemes in Britain and Ireland are organised by the BTO (British Trust for Ornithology). Each year over 900,000 birds are ringed in Britain and Ireland and this work helps in the study of bird movements, how many young birds fledge and survive to breed as adults, how many adults survive from year to year and how many birds disperse to different breeding sites.

This information is only discovered if the birds are re-trapped or, in Beccy’s case, are found dead and the ring recovered. So don’t be put off looking at dead birds, always check if they have a leg ring. If you do find a ringed bird then remove the ring (sorry, cutting the leg is the easiest way to do this) and send it to the BTO, The Nunnery, Norfolk, IP24 2PU, or the address stamped on the ring, along with as much information as possible but at least date found, location and grid reference, condition of the bird – freshly or long dead.

You will sooner or later, receive a report from the BTO, or the ringer, giving you information about the bird.

In the case of Beccy’s Siskin this took until 7th October but what it did reveal was that this female bird was ringed on 7th March 2013 at Polstead, Suffolk. Because ringers are highly trained and knowledgeable they are able to age birds by looking closely at the wing and tail feathers so we also know that when ringed this bird was in its 2nd year i.e. it hatched in 2012.

Given that Beccy found the bird at Ardvar it is likely that it was an Assynt bird which migrated south last winter to warmer weather and then returned to its natal area to itself breed. And, this is where it met its end – 106 days after being ringed and 793km from where it was ringed.

This is not unusual for this type of bird. The typical lifespan of a Siskin is two years with the oldest known bird having reached 8 years 1 month. Their status in the UK is resident breeder but they are also passage migrants and winter visitors i.e. they pass through and also winter in the UK – all this from a bird which weighs on average 15gms!

The second bird in our story makes for a happier tale. Many birds pass over Assynt on their spring and autumn migration and some of them stop at strategic locations to fuel up for the next leg. Bay of Culkein seems to be one of those locations, it’s not used by the huge numbers of waders etc. seen in the Forth Estuary or The Wash but it has its moments.

We may think autumn starts mid September in Assynt; many waders say otherwise. Having completed their breeding duties adult males will start to leave the breeding territory in mid-July and head south to their wintering grounds.

So it was not too much of a surprise to find over 90 adult Sanderling feeding in the bay on 15th July. This early in their ‘autumn’ many were still in breeding plumage, a really stunning sight as come winter they are very much a ‘black, grey and white’ bird.

Sanderlings are part of the same genus of Calidris sandpipers which includes Knot and Dunlin. One of the notable differences however is that the Sanderling has no hind toe which contributes to its very noticeable darting running action – a real joy to watch.

Amongst these 90+ birds was one with a combination of colour rings on each leg, no metal ring was evident this time. We get quite excited when we see birds with colour rings (we do get out a lot, honest) as it means we can record and report it and so add to the knowledge of the species and find out the bird’s ‘history’.

Colour rings mean someone is carrying out a study of that species and will want you to report your sighting – no need to cut off the legs, dead or alive, as all you need to do is carefully note the combination of colours from top to bottom on each leg then simply log onto the BTO website www.bto.org and click on “report a ringed bird” where you will get instructions on how to fill in the various boxes.

After a period of time!! you will receive a report, most likely direct from the ringer, giving the history of your bird.

We received ours, believe it or not, on 7th October, the same day as Beccy found out about her Siskin, not from the BTO but from Jeroen Reneerkens who is based at the University of Groningen, Netherlands where he works on ‘life history trade-offs in the long-distance migratory Sanderling’.

So what of our Sanderling? Well it was ringed on 2nd July 2009 at Zackenberg, Greenland as an adult bird where it was sharing incubation duties with a female which, from ringing data, is known to winter in Mauritania. Jeroen did comment that our male bird, unlike many other ringed males, has never been seen at its breeding area since 2009.

However, since being ringed it has been sighted as follows:

Date Location
14-7-2009 Baltray Beach, Ireland
11-5-2010 Pointe de Mousterlin, Fouesnant, Finistere, France
15-5-2010 Boutrouille, Kerlouan, France
09-5-2013 Pointe de Mousterlin, Fouesnant, Finistere, France
20-5-2013 The Ouse, Westray, Orkney
24-5-2013 The Ouse, Westray, Orkney
15-7-2013 Bay of Culkein, Sutherland

We will now put 2 and 2 together and probably get 5 but it does make for an interesting possibility. From data available it is known that Sanderlings incubate their eggs for 24-27 days and that the fledging period is around 17 days so a possible maximum of 44 days of family duties for this male (although he is unlikely to hang around for the whole fledging period). He was seen in Orkney on 24th May and then at Bay of Culkein on 15th July – that’s 52 days. Enough time for him to have left Orkney, gone to Greenland(?), attracted a mate, raised a family and headed south again – what do you think?

Sanderling do not breed until they are 2 years old so when ringed in 2009 our one was at least that age meaning that when we saw him he was a minimum of 6 years old. The typical lifespan of a Sanderling is 7 years and the maximum age recorded is 17 years 7 months so we could well see him a few more times yet.

The status of Sanderling in the UK is passage migrant/winter visitor as they breed in arctic North America, northern Siberia and Greenland and they winter in Europe (including Britain), southern Asia to southern Africa, Australia and South America – and what do they weigh? A massive 59gms!

So there we are two completely different birds with two completely different stories. One had no say in its end, one may go on to tell us more.

Enjoy them all.

D and A Haines

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