It is May, soon our Swifts will be back, but first are our House Martins. Having returned from their African winter grounds in the Congo, they incredibly find their way back to the same nesting sites year after year. Reusing old nests, saves a lot of time and vital energy. It is about ten day's work of collecting bill-sized pellets of mud from streams and ponds and gradually building up layers to create the nest, which will require around 1000 pellets, that’s 1000 journeys to a stream or pond floor. House Martins don’t like to land and only do so to collect the mud they need for their nests. So please never knock down that empty nest.
The House Martin is a small bird with glossy blue-black upper parts and pure white under parts. It has a distinctive white rump with a forked tail and, on close inspection, white feathers covering its legs and toes. They spend most of their time on the wing collecting insect prey, especially flies and aphids. House martins typically feed at a higher altitude than swallows, so the two species do not compete with each other, on a good summers day you may see both feeding in the same patch of sky.
Few birds are more social than house martins, before they moved to the eaves of our houses, they would nest in colonies of several hundred birds underneath the overhang of cliffs. The use of the familiar boy’s name, Martin, is a reflection of our now close relationship with this species, in the continent they are called House Swallows. Their full name here, House Martin, is only a couple of centuries old, the ‘house’ was added to distinguish it from other martins such as the Sand Martin. The Sand Martin can also be seen in Otley but is much less common and nests in sandy banks along the river, so is less familiar to us human residents.
The House Martin, weighing less than an AA battery, is still an appetising meal for some predators, if they can catch them! The Hobby, a migratory falcon is extremely agile in flight and is able to out manoeuvres the aerial acrobatics of the House Martin. Tawny Owls and Great Spotted woodpeckers take an easier route though and have been known to break the nests open to get at the chicks within. If the chicks survive to fledge, they can be hard to distinguish from the adults, they lack blue sheen and their tail is shorter and blunter. Their underparts are dirty creamy white, not quite the brilliant white of the adults.
House martins are one of the last of our summer migrants to depart in the autumn and some breeding pairs may still have young in the nest during September. Unusually for birds, young from the first brood have often been observed helping their parents feed the next brood. The presence of young so late in the year often prompts concern in us human onlookers, about their chances of survival, even with the help of their older brothers and sisters. If the weather holds and does not deteriorate rapidly in September however, then the young should be able to make their way south, feeding on the wing as they go.