Swallow General biology
Length: 20 cm.
Weight: 16-25 grams.
Wingspan: 33 cm.
The arrival of swallows is surely one of the surest signs that summer is on its way. The barn swallow, to give it, its full name, arrives in Ireland in April and will stay till September, before flying back to Africa for the winter. During its brief stay here it will be very active, building up food reserves and raising two, three or maybe even four families in this short time.
We are all familiar with the term; “One swallow doesn’t make a summer”. This old proverb, suggests that caution should be shown during the early part of May. Just because the first swallow has arrived, it does not mean that the weather will stay fine. This year was a classic example. A very good Easter has been followed by a very wet and windy last few weeks.
The swallow is most easily recognized by its long tail streamers and forked tail. The longer a male swallow’s tail streamers are, the more chance it has of mating. This is because the female picks the male with the most symmetrical tails. It is often difficult to see the other distinguishing features because they are almost always flying. They have long, pointed wings and gaping mouths that are used to catch insects when in flight. The head is a bluish colour with a red forehead and also a red throat patch. They have a bluish breast band, but the belly is creamy white. The sexes are very similar, but the female’s tail streamers are shorter than those of the male.
When they first return in early summer, they are very active, feeding on the wing and scooping water from the local river or canal. The males are the first to arrive and they are quick to establish their nest sites. The females arrive later. Some people believed that swallows hibernated for the winter and others even believed that they flew to the Moon!
Swallows have always held a special place in people’s hearts. Apart from heralding in summer, their delightful twittering is a joy to listen to and birds with a blue colouration have always managed to charm us – none more so that the Blue tit. In addition, their effortless movements through the sky is a joy to behold. Indeed, it was considered very bad luck to interfere with swallows. To destroy a nest or to kill a bird would result in continuous rainfall for a month and that cows milk would run dry (in North Yorkshire).
It is often said, that swallows can foretell the weather, just by watching them flying. High flying swallows is a sign of good weather, whereas if they fly close to the ground, it is a sign of rain. There may be some truth to this. Swallows feed on insects. These are more likely to be carried on thermals when the weather is warm and settled. If the weather is unsettled, they will be closer to the ground and hence the swallows will also fly close to the ground.
The name, barn swallow, is well chosen as one of the commonest places to build a nest is within a barn or outhouse. The nest is built of mud and lined with feathers. They gather up little pellets of mud in the beak and use these to form the cup shaped nest.
To strengthen the nest, they push small pieces of grass or straw into the mud walls. Up to 1,000 visits may be made to bring the mudballs to make the nest. Four or five eggs are laid. They are generally white with reddish flecks. These are incubated by the female and hatch after about 15 - 16 days.
The male and female are very aggressive at the nest, chasing off any intruders. The young are fed by both parents for about 21 days, after which they fledge or leave the nest. They can feed their young up to 400 times a day. During cold and wet weather, when insects are not flying, adults may have great difficulty in providing enough food for the young. After the young birds have dispersed, they will be fed by the adults for a few days before they set about rearing a second brood.
Because barns and cow sheds are no longer as common as they once were, swallows are no longer as common as they once were.
As summer draws into autumn, the days get shorter and the weather becomes cooler. This leads to a decrease of insects. Its now time to head back to Africa.
Swallows gather in large groups, often on telephone wires, chattering noisily to each other. Then suddenly, they are gone. The 6,000 mile journey to Africa has begun. Most cross the Mediterranean at Gibraltar, and after a brief rest, all head off again across the Sahara to South Africa. Migration is a hazardous time for the birds.
Many birds will die from starvation and exhaustion.
It’s hard to think that a bird that weighs less than an ounce, can travel thousands of miles every year and bring such joy to us for the summer months. That bird is the swallow.