FLYING AROUND THE FARLEIGHS WITH ROY MORRIS
WELCOME TO THE OWLETS
Led by Mary Seymour, an intrepid Tutsham Team recently turned out in force to welcome three young barn owls to the village. The nestlings, on the point of fledging and leaving their nest box for good, were held safely in bags then weighed, measured and given a ring with a unique ID to identify them should they be seen again or eventually found dead (hopefully of natural causes).
Each had one of its large primary feathers measured, as from this we can calculate its hatching date accurately to within a day. Such precise information, along with that from hundreds of other chicks, is used to estimate the size of the UK’s barn owl population (about 4,000 breeding pairs) and how it is changing. Between 1995 and 2020 their numbers increased by 225% - so a conservation Good News story, partly because they are being provided with nest boxes in suitable, vole-rich rough grass habitat, such as we have along this part of the Medway Valley.
At about two weeks after hatching, the owlets begin to grow their first flight feathers, then in a further two, with a good supply of voles brought in by both parents, feathers are sufficiently well grown for them to be able to maintain their own body temperature without an adult brooding them. At this point the adults will roost nearby during the day, leaving the youngsters on their own in the increasingly crowded nest. After eight weeks the first faltering flights are taken, but they return to the nest in between to await delivery of voles (and other small rodents, and even an occasional frog). If the weather is suitable – still and dry, as the adults hunt by sound so prolonged wind and rain is disastrous – they will be ready to fledge in their eleventh week.
Two of the owlets were close to being ready to fledge. The third was a week or so behind its siblings. This is normal, as owls’ and raptors’ clutches don’t all hatch at the same time – there is usually an interval of a day or two between each egg. This is a kind of natural ‘insurance policy’ in the event of bad weather and sufficient food not being available for all the young – the largest get a bigger share of the food, leaving the smallest – if necessary - to starve to ensure at least some of the brood survive. Indeed, in very hard times the smallest chick can become food for an older brother or sister.
But our three proved to be lusty youngsters clearly doing well on The Farleighs’ vole population.
They were also hosting their own ‘residents’ in between their feathers. While one was being ringed, a flat fly emerged and, after some deft handling of a specimen pot, was promptly captured. Just like humans, wild birds carry parasites and pathogens that can affect their health and sometimes prove fatal if there are too many. So, alongside data about the birds themselves, information is also collected about any parasites they are carrying as this not only helps us understand how the birds are faring, it can sometimes be a warning sign of potential danger to domestic animals and even human health – think Bird Flu for example.
As their name implies, flat flies have evolved to live in the space between birds’ feathers. In fact, they are so flat that it’s almost impossible to swat one if it lands on you. Our fly was duly sent off to the national monitoring scheme and was identified as a Common or Bird Louse Fly Ornithomya avicularia which is routinely found on barn owls – so nothing to be concerned about and they don’t harm the owl.
After an exciting hour of ooh-ing and aah-ing and serious data collection, not to mention perilous ladder-climbing, the three owls were returned to their box where they promptly settled down to await their first feed of the evening from a parent. The box has now been in place for four years and in need of a few minor repairs and certainly a good clean out when the birds have finally left. The Tutsham Team have this on their ‘to do’ list for the coming winter and will almost certainly welcome the owls again next year to watch their comings and goings as they continue to increase the local population. Well done to all concerned!