A season of success – 28 young burrowing owls!

The adult burrowing owls have been hard at work these past several weeks, incubating and raising their young. We have had the pleasure of watching 28 burrowing owl young grow from tiny 8 gram white fluff balls to 130-140 gram wide-eyed young owls. Burrowing owls are an endangered species in Manitoba and throughout their range in Canada. The Manitoba Burrowing Owl Recovery Program’s (MBORP) reintroduction activities to encourage nesting success has paid off. This season’s efforts have resulted in the highest number of fledged young since the inception of MBORP in 2010.

A burrowing owl, only a few days old.

Extremely dry summer conditions in 2021 have been ideal for nesting burrowing owls. Nests have remained dry and food sources are abundant with many grasshoppers around. Climate change is a real threat to species at risk like burrowing owls. Most species cannot adapt to these rapid changes and this negatively impacts these already struggling and small populations. During the 2010-2014 breeding seasons, captive-release and wild nests were plagued by flooding due to extreme summer storms event in southwestern Manitoba devastating most nests.

Another positive for the 2021 season is the absence of predation events. MBORP installs Reconyx trail cameras at all nest sites to monitor activities 24 hours a day. This season, only two observations of raccoons were noted on the trail cameras after young had hatched. These curious raccoons made no attempt to access the enclosure and ultimately left the owl burrows alone. All 28 owl young survived the early vulnerable nesting stages.

A raccoon spotted in one of the enclosure trail cameras.

To increase survival of young, we increase the supplement of mice provided to each family group. This encourages strong, healthy young and reduces sibling competition. Every few days we checked the burrows to make sure all young were accounted for during their first few weeks. I found that it was better to take a deep breath prior to opening the burrow lid, as the stagnant underground air of the burrow was filled with the smell of old mice and owl excrement. The odour only became increasingly unpleasant following the next several weeks of humid, 30+ ℃ temperatures. I couldn’t help but feel sorry for the young owls living inside, although I’m sure it didn’t even phase them as they don’t have a great sense of smell and they really do enjoy living in cow manure lined burrows and nests.

Burrowing owl young around 2.5 weeks old (left) and 4 weeks old (right).

When the owl young were roughly four weeks old we spent a full day weighing, banding, checking body condition and taking blood samples with the help of the veterinarians from the Assiniboine Park Zoo. (Read more about the weighing technique here.) Banding burrowing owls allows us to identify individuals along migration and on the breeding grounds in the northern U.S. and in Canada. Should anyone observe one of the owls banded by MBORP, they can report the unique alpha-numeric colour coded band to the Canadian Wildlife Service bird banding office or to a local conservation organization. This information will find its way back to the bander/conservation program.

There are a lot of questions about burrowing owl migration. It’s suspected that up to 50% of young do not survive their first migration due to several challenges they face along their migration path. The species faces many of these same challenges on the breeding grounds as well.  We hope to learn more in the next few years with the use of satellite transmitters technology.

Owl young are not sexually dimorphic, meaning their sex cannot be determined by looking at them. Therefore, a small blood sample was taken from each owl for genetic testing, which will determine each owl’s sex. This information will be used to determine which young will be held back for next season’s reintroduction program.

A small amount of blood is drawn from each owl young.

After receiving the blood sample sex results, MBORP removes select young from nests for the breeding and release season for the next year. Removing a few young from each nest will help increase their chances of survival of the young remaining in the wild as there is less competition for food and this ultimately increases overall body condition prior to migration. We want to give each one of these  burrowing owl young the best chance to survive to fledging, post-fledging on the breeding grounds and navigating their first migration. Watching these unique little owls grow in front of our eyes has truly been a surreal and rewarding experience.