I have discovered that the instinct to nurture and protect young is so fiercely ingrained in birds of prey that it is possible to get them to act as surrogate mothers and raise chicks that are not their own.
This year, I have successfully re-homed kestrel, barn owl and tawny owl chicks that have been found and handed in to me, putting them back into wild nests. Now wildlife rehabilitation centres have even begun to bring me rescued chicks, which I ‘foster’ onto unsuspecting parent birds. And I’ve been sharing my findings with the World Owl Trust of which I am a patron in the hope that it can help their conservation efforts abroad.
Last year I put the parenting skills of a pair of tawny owls to the test by persuading them to take on six extra owlets: making their entire brood up to 10! I helped support this large brood by offering food to supplement their diet until the chicks became independent.
Then this year I pushed the boundaries further by persuading a pair of barn owls to accept two foster barn owl chicks before their own eggs had even hatched. A farmer had found these chicks after emptying out a barn of straw and brought them to me. They were less than a week old and were very frail. They needed to be kept warm so I put them on a heat mat in a box in my porch while I decided what to do with them. I have raised owlets this size before, feeding them every couple of hours and trying to release them back into the wild when they are full grown. But the young chick can become ‘imprinted’ on you, mistaking you for its real mother. It causes them real difficulty when they try and make their own way in the wild as they are instinctively drawn to humans. It makes far more sense to get a wild owl to raise them if you can.
Earlier in the year a pair of barn owls living close to my gallery that had just won a vicious battle with a kestrel over a nesting site. I already had this nesting site wired with a camera which could relay live video footage to a screen in my studio. So I decided to foster the barn owl chicks onto this pair so that I could see how the female took to the new chicks and monitor the situation in case I needed to intervene if things started to go awry. I have put chicks into a barn owl nest before but always when the bird’s own chicks had hatched and were already well grown. But this pair was still incubating eggs in a nest box in a sycamore tree so I was unsure how they would react.
That evening I got my ladder out and propped it against the tree. The female flew out as I climbed up the rungs with the chicks balanced in my left hand. As the box was vacated I could quickly place the two chicks next to the still warm eggs. I left as quickly as possible and headed back home. I was intrigued to see on screen how these new chicks would be received. I was surprised to see that the female owl was already inside the box by the time I got back. She was standing over the chicks, looking down at them in surprise, as if to say, ‘Cor blimey I’ve only been gone a second’. She reached down with her beak and hesitated. For a horrible moment I wondered whether she was going to brood them or eat them. Then she touched each chick with her beak and started to try and work out how she was going to get these helpless wriggling white blobs underneath her to brood.
It was important that these young chicks survived as 2015 has been a very disappointing year so far for breeding barn owls. Their success is closely linked to the availability of their main prey, field voles. Vole numbers fluctuate along a four to five year cycle, but these cycles can also be affected by the weather. Last year, for instance, there was a relatively mild winter followed by a great summer and this brought about a ‘boom’ year for voles. Consequently it was the best year on record for breeding barn owls, with many pairs rearing two clutches of chicks, which is known as ‘double brooding.’But this year there has been so few voles that females have not been able to eat enough to get into healthy breeding condition and when they are below a certain weight they don’t bother to breed.
I had rung the female the year before with a colleague so I knew that she was a new parent and these two extra owlets were her first ever chicks. She didn’t seem to know how to go about brooding them and where to put her long sharp talons. She kept lifting one foot and then the other and clenched her claws into a tight fist in an attempt to keep the chicks safe but she still managed to stand on them in the process. Talk about being all fingers and thumbs!
I watched as she pecked at her own feet in frustration, but finally, after a lot of fidgeting, she was sitting on her new brood.
Just before midnight the male arrived in the nest box. Whenever he comes into the box he always briefly greets her and then tries to mate her. Normally when he does this, even if she is incubating the eggs, she bows her head in submission. But this time she looked him straight in the eye and pecked at him in disbelief. He took a step back in confusion, as if to say ‘What’s wrong with you tonight?’ before stepping forward to try again. But again she rebuffed his advances, this time standing up with her wings out and pushing him around the large nest box, pecking him all the while. She forced him into the far corner and made him stay there while she returned to tend to her chicks. She sat back carefully onto her cherished owlets a look of complete contentment writ large across her face and then glanced up disdainfully to check that the male was keeping his distance. He watched on forlornly from the sidelines and shuffled around the edges of the box.
It was fascinating to watch but even better to see that she had taken to her role as surrogate with such dedication. The next morning I watched as she fed the chicks in turn, each chick tucked neatly under a wing. A week later her own eggs hatched. There was a sizable difference between the largest and smallest chick in the nest, but this didn’t overly concern me. It is perfectly natural for barn owls to have a range of differently sized young. Barn owls incubate the first egg as soon as it is laid while most birds lay the whole clutch of eggs before starting to incubate them, so that they all hatch at the same time. A barn owl usually lays one egg every three days. So if they lay six, there will be 18 days between the oldest and youngest chick. This, however, can present a very nasty problem. The chicks grow so fast that the largest is big enough to swallow the youngest one whole.
But, I’m putting out extra food for this artificially expanded family so I’m hoping that that these four chicks will all make it to fledging time. They will certainly be an added bonus for the population of barn owls on the Yorkshire Wolds this season. And I’m hoping that this wild surrogacy technique that I’ve honed near my home in Thixendale can be used in conservation projects around the world to help increase populations of endangered owl species in the future.