The local hospital grounds have their own resident swans. Last year they hatched six eggs and reared four young. I was surprised to see the adults and at least two of the cygnets (now as big as their parents) still around in the depth of winter (January I think); apparently not having migrated. I expect this was because they got well fed by hospital staff and visitors - so why bother?
Is this common among swans and other migrants in a similar situation?
You've got it right. Birds won't migrate if they don't need to. If the conditions are bad, they go South, but only as far as they need. But if they find unfrozen lakes with sufficient food and safe places to rest, they will stop there. In the age of feeding wild birds, many migratory species have populations that become resident, at least in towns, and also expand their range North.
Mute Swans and other birds have northern populations that are summer visitors to their breeding grounds, but southern populations are resident. Even birds that we think of as strictly migratory, such as the Barn Swallow, have resident populations in areas that can sustain them year round, as seen on this map.
In Britain, as you can see on this RSPB fact file, Mute Swans are resident birds, even though individual birds or families may wander away from the nesting sites.
Thank you for that information - very interesting. I read that local populations of some species, such as starlings, only migrate for short distances - perhaps only a few miles - but never realised that even swallows don't always migrate. But how would they find enough insects in winter?
Re swans (mute swans that is), I went to a local park with a friend recently and we were feeding the birds on the lake with (wholemeal) bread. There were parent swans and a couple of what I assumed were their youngsters. The parents chased the cygnets away from the food quite aggressively, beating with their wings and pecking at them.
Starlings are not strictly insectivorous. They can eat berries, soft fruits, seeds, or bread in towns. That’s how they survive long, harsh winters in towns like Montreal. So these species that can switch diets with seasons, are able to live as residents. Tits do the same thing, you know they eat sunflower seeds at bird tables. But they also search the trees for hibernating insects, usually eggs and nymphs hidden on branches and trunks. We humans are able to count the eggs and make an estimate of next summer’s level of infestation with some insects seen as forest pests. But so do the tits! The ones that feed on many insects during winter will lay more eggs in spring, so many chicks will be fed on an abundance of larvae, as predicted by the abundance of eggs.
Swallows are resident in warm, wet areas, where insects are abundant all year round. Why would they leave then?
Adult Swans and other resident birds will chase away their progeny when ready to live independently. They will not tolerate competition for resources, and the young are going elsewhere. That’s not migration, but dispersal.
Hi again Florin, thanks for the information.
You said: "Swallows are resident in warm, wet areas, where insects are abundant all year round. Why would they leave then?"
Not sure if I understand this comment. Some species of swallows do migrate to temperate climates to breed, then return to warmer climates in the winter. I supppose because of the flush of insects, (and perhaps less competition from other kinds of swallows?) during the temperate summer. When I went to work in Africa there were a number of resident swallow species but also our familiar European swallows that came during the Northern winter.
You mention Montreal, do you live in Canada? Maybe things are a bit different there?
Sorry about getting back so late.
I meant to say that Barn Swallows (Hirundo rustica) are summer visitors on most of their breeding grounds in the temperate region, including Montreal and London. But the populations breeding in warm areas such as Egypt are resident birds there; they don't need to fly away in winter, because they can find food all year round. The same thing with the Red-rumped Swallow (Cecropis daurica), who visits Southern Europe during the summer, but is a resident bird in India and Africa. In those places, in winter, you will find both the local birds and the northern populations, living together for a few months.
There are also many species of swallows that never migrate, such as the Congo Martin (Riparia congica) and the White-bibbed Swallow (Hirundo nigrita), both from insect-rich areas of Africa. I had these species and those Egyptian populations of the Barn Swallow in my mind when I was asking "why would they migrate?"
It's the same in North America. I lived in Montreal for almost four years. The Barn Swallows there have a red belly instead of white, but they are the same species.
In general, the areas where the birds nest is considered their home land. Of course, penguins and other sea birds are at home in the high sea, and go on land only briefly, to nest. But Honey Buzzards come here in Britain every summer for a few years until they mature, before even establishing a territory and nesting. So I would say that they are truly at home in Britain and are migrating to Africa to spend their winter, and not at home in Africa and rushing to Britain only to breed.
All the best,
Thanks agai Florin, got you now!
I spend several years in East Africa and it was a bird watcher's paradise! I don't think there were any swans (ARE there swans in Africa???) but there were lots of other birds. My favourite swallows were the tiny striped swallows. They had striped breasts and several of them used to sit in rows on the wires and make musical little "screep, screep, screep" sounds, like fairy violins tuning up! We even had a couple of crowned cranes in the garden - seemed like a youngster with a half grown crest (like a blond crew-cut) and its parent. The parent was honking gently to it as they stalked across the lawn. Various kinds of eagles and other birds of prey were fairly common, and Hammerkops sitting on the wires above roadsides - and even once a wild grey parrot. Lots of smaller birds too, whydahs, babblers, ibises, bulbuls, the water bottle bird (coucal) whose call was like water bubbling out of a bottle, sunbirds and bishop birds with their bright colours, mousebirds that ran along branches like mice and used to nibble holes in pawpaws, weavers, glossy starlings, firefinches etc etc, as well as some familiar European migrants...
Makes me "homesick" to think of them!