During the spring, you may have noticed wooden nest boxes on poles popping up around the Park and Zoo. The Conservation and Research team has installed these nest boxes to increase available nesting habitat for tree swallows. Tree swallows are aerial insectivores (a bird that hunts insects while flying), which have suffered population declines over the past 50 years in North America. These declines may be caused by reduced insect abundance, climate change, and a reduction in available nesting habitat.
These nest boxes are monitored throughout the breeding season. We are happy to report that since the nest boxes were first installed in 2019, a family of tree swallows has successfully used them to raise a nest of young each year!
This year, we invited Kevin Fraser's team from the Avian Behaviour and Conservation Lab at the University of Manitoba to come band the tree swallow family occupying one of our nest boxes in the Zoo.
Opening the nestbox in the Zoo
A tree swallow nestling
The Avian Behaviour and Conservation Lab at the University of Manitoba works on a wide variety of bird research programs focusing on aerial insectivore monitoring and studying bird migration. We collaborate with them on the nest box project, and the purple Martin condo, and the Zoo has supported their migration research on robins that use Assiniboine Park before migrating in the fall.
Their team carefully removed six nestlings and one adult from the nest box to be weighed, measured and banded. The birds were placed in a breathable fabric bag to be weighed, and then wing and tail measurements were taken using a ruler. A leg measurement, tarsus length, was also measured with callipers, which is part of a bird's leg between what appears to be a backward-facing 'knee' and what appears to be an 'ankle'.
The team measured the wings with a ruler
Tarsus length was measured with callipers
The birds were banded with a tiny metal band with a unique identification number. The bands should remain on for life and as birds’ legs are widest as nestlings, there is no adjustment needed as they age and no negative impact on the birds. The bands allow us to know what birds return year after year and contribute to the collaborative network of bird banding across North America.
A question you may be asking yourself is “Don’t mother birds not return to care for their young if they are touched by humans?”, though this is widely believed, it is considered a myth. Of course, it is always best to leave wildlife alone and avoid human contact, but when a young bird is held by trained professionals for research purposes, the parent birds will return to care for their young.
A quick note that if you ever spot a young bird on the ground, it may be a fledging that is learning to fly and should not be picked up. Wildlife Haven has useful information on what to do if you come across injured, sick, or orphaned wildlife.
Adult tree swallow with an identification band
We are thrilled to see the nestlings in our nest boxes grow up and fledge in the coming month. We invite you to join us in our conservation efforts for tree swallows by helping to maintain their food source. By avoiding insecticides or pesticides and planting natives plant species in your garden, you can attract beneficial insects and provide a food source for aerial insectivores.
