Housemartins

Question

Hi everyone 
 The is a Housemartins nest in the eaves across the road. I have become fascinated by these fabulous little birds and this has given me questions I should love the answer to if any of you would be so kind?? 
 1. They often congregate airborne around the nest having obviously taken on food - but not all of them enter the nest site although many approach and then shear away. Why is this? 
 2. I have noticed that in the evening just befor dusk they often fly over a short distance in a tight group -, and suddenly they disappear!! Are they roosting together in a nearby tree?? 
 3. Do any of them actually live in the nest where the young are? 
 4. As they are still apparently feeding young at sept 1st, will this brood be strong enough to migrate to Africa in a few weeks and will they sleep on the wing during the journey? 
 Thanks in anticipation for any relevent info! 
 steve

Goldcrest · Answer

A warm welcome to the forum Steve. 
 I had Housemartins nesting for several years at my house, the nests are still there but we have not had any breeding pairs since 2006. I really miss them. 
 I asked a question on this forum last May and was given this interesting link by one of the moderators, IanH. 
 http://www.bto.org/home/house_martins_2009_final.pdf 
 which may answer some of your questions. 
 These are my attempts at answers but I am definitely not an expert. Hopefully by bumping up this thread one of our experts will confirm or refute my answers. :-) 
 1. When the original pair have a second brood, the first juveniles often swoop to the nest and can help with the feeding. They are very "family orientated" birds. 
 2. Fledgings only return to the nest for a week or so and not every night. They do remain in family groups so it does seem very likely you are correct. 
 3. I am not 100% sure but I think the female will stay with the young but when they get to a certain age there is just no room for extra adults. 
 4. One year, ours had a very late brood and I remember how concerned I was. Luckily, they all fledged and had time to strengthen their wings before disappearing with the other families. Late broods are often successful. I do not know if House Martins sleep on the wing but I would imagine they have to for some of the journey. 
 I hope some of this has helped and I do apologise if I have got anything wrong, I do not pretend to be an expert. 
 I do agree they are fantastic birds and we loved having them. This month, several were swooping in and actually entering our old nests so I am hoping they are youngsters who are planning their accommodation for next year. Fingers crossed.

Trochilus · Answer

House martin roosting behaviour is quite interesting. When the birds first arrive in the spring, the adults roost mainly in the nest, but to some extent, also in trees. If the birds are hit by severe weather early in the season, they have a habit of roosting communally to save energy and body heat. They may huddle together in a tree, or use a nest - a record of 14 house martins have been found roosting in one nest! As the chicks grow, one of the parents sometimes stops roosting in the nest, and moves out to a nearby tree or other sheltered site. Having said that, frequently the whole family roosts in the nest, even after the young have fledged. Fledged young often roost in a neighbouring nest especially if their parents are rearing another brood. Normally, but not always, the chosen nest is unoccupied. There is a record of a nest with two adults, one chick and four strange fledglings from a nearby nest! Aerial roosting is not proven, but there is circumstantial evidence to suggest that it happens. During migration and in their wintering grounds, house martins roost in trees and on various ledges. Unlike swallows, they only rarely roost in reedbeds. On migration, the birds often roost in house martin nests they come across en route.