Migration Research Foundation - Research - Short-eared Owl

RESEARCH

SHORT-EARED OWL

BEHIND THE SCENES - THE GERBIL STORY

In order to study the movements of Short-eared Owls, we need to capture them and equip with them with standard leg bands at a minimum, and colour markers or lightweight transmitters where possible.

Unfortunately for us, Short-eared Owls are notoriously difficult to catch. We have spoken with several researchers who have had success over the years, but all emphasized that considerable amounts of time, patience, and creativity will be needed before we 'figure out' the Ontario population.

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In the summer of 2003 we began using bal-chatri traps to catch the owls - essentially small cages containing a lure animal, and lined on the top with nooses made of fishing line that would entrap the owl's feet when it lands. This is one of the oldest methods known, and has been used successfully on raptors of all sizes, from kestrels to eagles. The risk of injury to the bird is very low, and the lure animal inside also is completely protected from physical harm (one might expect them to be scared by the presence of the predator so close, but in our experience there's little visible evidence of that).

For those first few months, our lure animals were three female mice. Generally easy to handle and take care of, but ineffective for our purposes in that they tended to sit still inside the cage, providing no aural or visual stimulation to attract the owls. Smart mice!

After a few months of 'retirement' for the mice, it came time to try some winter trapping, this time with new bal-chatri traps painted white to blend in with the snow. Since the mice had been unhelpful in the summer, and likely weren't too cold hardy, we decided to buy two gerbils, which have received high praise from some raptor banders as being highly active lure animals. Active they were, and we nearly had success on a couple of occasions - it seems though that we have just a bit of fine tuning yet to do with our traps.

To our chagrin, they were also active in other ways. While we had been assured that both gerbils were female, one of them was growing ever larger, and sure enough, one night in March we found that the cage had eight new inhabitants. We immediately separated the adults, much to the dismay of the male, who was all over the female (literally) as soon as the first litter was born.

Eight was apparently an exceptionally large litter, and only six of them survived. Even so, that was far more than we knew what to do with. But before we could begin addressing that problem, it became worse - returning from a week-long course, we found that another six had been born! As of early June, all are independent - and we have learned from experience how to separate males and females better than the staff at the pet store!

HOWEVER - we still have far too many gerbils! If you are in the Montreal or Ottawa area, we would be happy to offer you two, three, or more (in all seriousness, they are social animals and it's better to have at least two or three together). Click on the photos below for larger versions. Please e-mail us for more information.