Out of the common four similar species that come to the uk (House & Sand Martins, Swallows and Swifts) why do the swifts leave so early? What's in it for them by doing so? Or is it that our climate is just not good enough for them? During our summer months they have much more light per day for feeding than they would have in Africa so why could it be?
-
Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.
Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
Why do swifts leave so early? (1 Viewer)
- Thread starter Mannix
- Start date
Possibly the earlier late summer rapid decine in insect density at the higher elevations usually frequented by Swifts who are far more specialised aerial feeders than the three hirundine species. The House Martins which have successfully nested under the eaves of my house every year since it was built in 1972 hawk for their insects at or a little above house roof level.
The Martins and Swallows hawk for their insect food at much lower elevations than the Swifts rarely ever do, the Swallow often skimming at speed very low over water for insects that lurk on or just above the surface.
Maybe other factors too play a part but air temperature warmth is essential for most insect flight. Insects unlike the birds are cold blooded and need warmth to fly freely. Birds generate their own body heat being warm blooded.
joannec
Well-known member
Hi Mannix
Swifts are always on the wing except for nesting....they feed on the wing, sleep on the wing, mate on the wing and if they could nest on the wing, they would. But that is beyond even them. So coming to northern Europe is incidental in the life of swifts; they only come here to nest because of our plentiful summertime insect supply. Flying insects are their only food source. Once nesting is finished they are off....on the wing again and by the end of the summer insects are beginning to decrease in number. There is no longer any reason to remain. They go wherever there are abundant insects.
They are so well adapted to flight that if the weather is cold and wet when they have chicks in the nest and there are few insects about the parents will travel hundreds of miles south to feed where it's warmer and there is a better food supply, sometimes they are gone for days. The chicks go into a sort or torpor state which they survive, I don't know for how long. The parents return when the weather improves and continue with the chick rearing. Then once the business of rearing chicks is completed they are off.....following their insect food. But they may return later on feeding forays if the conditions are suitable. In fact I saw a swifts in Sussex last year in October.
Joanne
Swifts are always on the wing except for nesting....they feed on the wing, sleep on the wing, mate on the wing and if they could nest on the wing, they would. But that is beyond even them. So coming to northern Europe is incidental in the life of swifts; they only come here to nest because of our plentiful summertime insect supply. Flying insects are their only food source. Once nesting is finished they are off....on the wing again and by the end of the summer insects are beginning to decrease in number. There is no longer any reason to remain. They go wherever there are abundant insects.
They are so well adapted to flight that if the weather is cold and wet when they have chicks in the nest and there are few insects about the parents will travel hundreds of miles south to feed where it's warmer and there is a better food supply, sometimes they are gone for days. The chicks go into a sort or torpor state which they survive, I don't know for how long. The parents return when the weather improves and continue with the chick rearing. Then once the business of rearing chicks is completed they are off.....following their insect food. But they may return later on feeding forays if the conditions are suitable. In fact I saw a swifts in Sussex last year in October.
Joanne
Barred Wobbler
Well-known member
Saw a couple of swifts today. Late for these parts. The last ones I saw were about 10 days into August.
Songkhran
Well-known member
Yes 1-2 at Cley today and 2 West at Sheringham, there were some in off two days ago as well, got strongish SW's at the moment so are these late departers or birds blown over from the continent?
RecoveringScot
Well-known member
I saw 30+ SW on 24th August here in Aberdeen and there were still 4 going SW on 31st August, both days when significant numbers of hirundines were also on the move. Stiff breezes have been a feature of practically the whole summer up here, and recently there has been increased rain, so perhaps this rather later departure than last year is influenced by lack of suitable weather conditions for migrating.
Cheers,
Phil
RecoveringScot
Well-known member
A few years ago here in Aberdeen I briefly saw a Swift (not close enough to identify as to species) on 9th November. Pallid Swift is actually more likely that late, but I couldn't really say that mine looked anything other than Common Swift on first impression. I spent another day or two hoping it would show up again. There were single records of both House Martin and Swallow around the same time elsewhere in town. The weather was unusually warm and fine for the time of year.
Unfortunately it didn't return for a closer look.
Cheers,
I do actually know this. We have swifts nesting under our eaves every year and during most part of the day they feed at quite a low level. The only time they disappear upward is at night. But to my mind they will get up to 8 hours more light for feeding their young over here than they would near the equator and I think that this is a major rerason for them coming here. That is assuming that they do not feed in the dark. I would think that Africa has a hell of a lot of insects flying about so I don't personally think they come here for that reason. If it was for that then why leave so early?
KnockerNorton
Well-known member
swifts need good weather to feed at their high altitude niche. In poor summers they leave early. They also move ahead of weather sysstems, which tells you all you need to know - they're following the good weather and the high flies.
John Cantelo
Well-known member
A related question, but I've never quite understood why Pallid Swift (whose Mediterranean distribution suggests preferance for warmer climes) arrives in Spain in late Feb/March and departs in October whilst Common Swift, which can cope with cooler northern latitudes, arrives (broadly speaking) a month later and departs a month earlier.
Suggestions?
John
Suggestions?
John
deborah4
Well-known member
Hi John
I've read somewhere it's to do with the length of the breeding season (longer in Pallids who's breeding is less effected by temperate weather ie. postpone egg laying until eg. June subject to change in weather). So ... number of broods perhaps cf. to Common Swift
edit: Also perhaps because they have a shorter migration than Common Swift so can spend longer in their breeding ground, which is presumably connected with the above point!
I've read somewhere it's to do with the length of the breeding season (longer in Pallids who's breeding is less effected by temperate weather ie. postpone egg laying until eg. June subject to change in weather). So ... number of broods perhaps cf. to Common Swift
edit: Also perhaps because they have a shorter migration than Common Swift so can spend longer in their breeding ground, which is presumably connected with the above point!
Last edited:
deborah4
Well-known member
Only a quick google but found this John (excerpts below} might help explain some of reason for earlier departure of commons cf. to pallids
http://www.londons-swifts.org.uk/PhotoGallery..htm
'Pallid Swifts spend the winter months in an area from West Africa and the Sahel, across to the Sudan and Ethiopia, and so have a much shorter migration than does the Common Swift.
Because of this they can spend longer in the breeding areas, (from April to November in Southern France), and can raise two broods.'
and this article which you may find interesting (I can't access the whole article but you may be able to)
Abstract
The reproductive ecology of three colonies of pallid swift in a warm continental climate (Piedmont, NW-Italy) was studied over a ten years period. About 60% of the clutches were laid in late May and June, but continued until late August and September, when some females laid a second clutch. Clutch size and the mean number of fledged young decreased progressively from spring to autumn. Laying dates were influenced by rain and temperature: unfavourable weather conditions during May induced most females to postpone egg laying until June. Clutch size was not related to the rain or temperature parameters considered. These observations differ from the findings about the common swift studied in cool temperate areas, where a very short stay in the breeding colonies does not allow a delay in laying, and spring weather conditions therefore have a strong influence on clutch size. There are also differences about the effect of weather on chick rearing. In warmer climates, typical of our colonies, fledging success is hindered both by too dry or too rainy seasons, even if these situations very rarely occur and the three-egg clutch is always the most productive. In colder climates the breeding success of the common swift depends primarily on the climatic conditions of May, and in bad weather a two-egg clutch is more productive than a clutch of three. In summary, the annual breeding success of the pallid swift appears little influenced by weather changes, due to a lesser impact of adverse conditions in Southern climates and the possibility, for this species, of shifting the laying period in response to a temporary worsening of climatic conditions
http://www.jstor.org/pss/3683188
http://www.londons-swifts.org.uk/PhotoGallery..htm
'Pallid Swifts spend the winter months in an area from West Africa and the Sahel, across to the Sudan and Ethiopia, and so have a much shorter migration than does the Common Swift.
Because of this they can spend longer in the breeding areas, (from April to November in Southern France), and can raise two broods.'
and this article which you may find interesting (I can't access the whole article but you may be able to)
Abstract
The reproductive ecology of three colonies of pallid swift in a warm continental climate (Piedmont, NW-Italy) was studied over a ten years period. About 60% of the clutches were laid in late May and June, but continued until late August and September, when some females laid a second clutch. Clutch size and the mean number of fledged young decreased progressively from spring to autumn. Laying dates were influenced by rain and temperature: unfavourable weather conditions during May induced most females to postpone egg laying until June. Clutch size was not related to the rain or temperature parameters considered. These observations differ from the findings about the common swift studied in cool temperate areas, where a very short stay in the breeding colonies does not allow a delay in laying, and spring weather conditions therefore have a strong influence on clutch size. There are also differences about the effect of weather on chick rearing. In warmer climates, typical of our colonies, fledging success is hindered both by too dry or too rainy seasons, even if these situations very rarely occur and the three-egg clutch is always the most productive. In colder climates the breeding success of the common swift depends primarily on the climatic conditions of May, and in bad weather a two-egg clutch is more productive than a clutch of three. In summary, the annual breeding success of the pallid swift appears little influenced by weather changes, due to a lesser impact of adverse conditions in Southern climates and the possibility, for this species, of shifting the laying period in response to a temporary worsening of climatic conditions
http://www.jstor.org/pss/3683188
dantheman
Bah humbug
. . . They just like to make a swift exit. No flies on them. :t:
The flight of some swift species is characterised by a distinctive "flicking" action. Swifts have a worldwide distribution in tropical and temperate areas, the swifts of temperate regions are strongly migratory and winter in the tropics. Some species can survive short periods of cold weather.
The resemblances between swifts and swallows are due to convergent evolution reflecting similar life styles based on catching insects in flight.
---------------------
gwen
Guaranteed ROI
The resemblances between swifts and swallows are due to convergent evolution reflecting similar life styles based on catching insects in flight.
---------------------
gwen
Guaranteed ROI
