It's been a record-breaking year for cranes flying in to winter at RSPB Lakenheath Fen
This month I really wanted to highlight the success of common cranes in the Cambridgeshire Fens, following a record-breaking high count of 78 birds in a winter flock at the Nene Washes on October 22. This is the highest count for at least one hundred years, and represents the cumulative efforts of several individual nature reserves and private landowners in the local area in providing suitable and safe habitat for the birds to breed and overwinter. This record was broken at 18:10 on that day, approximately five minutes after sunset, when 72 birds flew overhead of stunned onlookers to join six that were already on the ground feeding.
This winter flock is an annual event as birds from parts of Suffolk, Norfolk and Cambridgeshire migrate a short distance to spend the winter together. Their preferred meeting point are the agricultural fields around the Ouse Washes, but especially high rainfall there in autumn effectively flooded them out and meant the group – at the time of writing in early November – have moved to the Nene Washes instead.
Wherever they are, they are omnivores and will feed on a variety of food items such as insects, root vegetable crops such as sugar beet, earthworms, slugs or the stubble left behind in arable fields; maize is popular. The cranes are very sociable in the winter with individuals, mature pairs and small families (a pair with one or two chicks from the previous summer) mixing and socialising with each other before breaking apart again in late February or early March to return to their summer breeding grounds.
In the summer though, the birds’ hormones take over and things heat up, and it is now that cranes don’t like sharing! Our two pairs have a definite territory boundary and will bugle (call) and display to each other to mark where their patch starts and ends.
They make excellent parents when mature, and we often know when the first egg of the season has been laid as we suddenly only see one bird in a territory, instead of the pair together. From this moment onwards the egg or chick isn’t left unsupervised and will have its parent(s) with it until it joins the wintering flock several months later.
This year, we had our traditional pair, A2, who raised one chick, and a new pair, B2, who didn’t – they seem to be young birds and perhaps inexperienced, and it is likely that not only did they choose an unsuitable nesting spot, but it appeared they also left the egg(s) unattended. In time we hope they will get the hang of things!
We noticed that pair A2 and pair B2 (the new birds) weren’t as territorial as separate pairs usually are, which may indicate that one of pair B2 is the offspring of pair A2 from a previous year – common cranes seem to have good memories of each other and they form strong bonds that last over time.
Much of the insight we have each season into the breeding success of ‘our’ birds, and also updates from the wintering flock, come from Norman Sills, who keeps a careful watch on them and used to be our site manager here. At this time of year, we are starting to think about the conditions the cranes will want on the reserve to tempt them to breed again next spring – water levels have to be just right, and they like a variety of reedbed density, too, made up of areas that have been recently cut and some that are more mature. We hope that, over time, we can keep using Lakenheath Fen to contribute to growing the Fens’ crane population even further; at the moment the future looks bright for these special birds.
If you have any queries about the cranes, you can get in touch with us on 01842 863400 or email us at firstname.lastname@example.org and we’d be glad to answer them.
Hope to see you soon.
Visitor Experience Officer
RSPB Lakenheath Fen