Barn swallows thrive in Park horse barns

The colony of barn swallows (Hirundo rustica) in Stanley Park did well this year. Barn swallows are protected under the Migratory Birds Convention Act, 1994 (Environment Canada 2004) which makes it illegal to intentionally damage or destroy their nests, eggs, or young. They are also provincially blue listed (“of special concern”). In Stanley Park, you can see barn swallows and hear their chatty calls as they feed on flying insects over Lost Lagoon and Beaver Lake. Their nests are found at the Mounted Police horse barns and at one of the Vancouver Park Board’s equipment shed. (Figure 1)

Figure 1. Buildings in Stanley Park with active barn swallow nests are highlighted in blue. Image from GoogleMyMaps

The swallows migrate to Central and South America in September for the winter months and return to our region in April. With an average lifespan of 4 years, adult barn swallows mostly come back to the same breeding site year after year and often reuse the same nest (Shields 1984). SPES started monitoring the barn swallow colony in 2014 with the protocol of Barn Swallow Conservation Project (2014). This year, volunteer Marisa Bischoff and SPES Conservation Technician Ariane Comeau conducted 22 barn swallow surveys from March to September in order to understand: how the swallow numbers are changing year after year, if nests are being built at new sites within the Park, and to apply best management practices when needed, including informing the best timing for Park operations and other disturbances (Worcester and Titaro 2012). The passive monitoring survey consists of observing with binoculars all of the nests within the colony and noting:

  • The timing and length of the arrival
  • The type of activity such as nest building, incubating, feeding hatchlings
  • The number of hatchlings/fledglings and the number of deaths
  • The number of nests that are used for two broods
  • The last sighting before migration

Because parents incubate their eggs for 12-17 days and the young are fed and grow in their nest for 15-27 days (Brown, Brown 1999), conducting the survey once a week ensured we would have an accurate estimate of the number of incubated nests and fledglings. Conducting the survey more than every 5 days is not recommended as it could stress the colony (Barn Swallow Conservation Project 2014).

3 fledglings ready to leave. (Photo: Ariane Comeau/SPES)

In March 2018, we surveyed most of the buildings and bridges in Stanley Park to find unknown barn swallow nests, but none were found. Juveniles usually disperse from their natal site when breeding for the first time (Shields 1984), so new colonies may occur in the Park from the offspring of the known colony. The only colony in the Park we are aware of is the one at the Mounted Police horse barns and Vancouver Park Board’s equipment shed. The first male barn swallows to return were observed on April 13 (they come back earlier than the females to choose and fix their nest). Out of the total 80 nests of the colony, 40 of them were active, including 10 nests that were used for two different broods. A total of 131 individual hatchlings/fledglings were observed, which gives an average of 2.6 young per active nest. That is an increase from the year before when we observed 80 young out of 54 active nests (average of 1.4 young per active nest). In 2017, more nests were active and more parents incubated, but not as many had successful fledglings.

Male swallow flies off after feeding its young. (Photo: Jeannine Johnstone/SPES)

Barn swallows construct mud nests often under roofs and use soft material like feathers and horse hairs (Figure 2). If you detect a barn swallow nest, you can report it to coastwildlife@gmail.com or call 604-989-1007. If you find an injured barn swallow, you can call Wildlife Rescue Association at 604-526-7275.

References

Barn Swallow Conservation Project, 2014. Barn Swallow Nest Monitoring Methods. Retrieved from https://bcswallowconservationproject.files.wordpress.com/2014/05/baswnestmonitoringmethods.pdf, Accessed October 25 2018.

Brown C. R., Brown M. B., 1999. Barn Swallow (Hirundo rustica), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.452; Accessed on October 25 2018.

Environment Canada, 2004. Migratory Birds Conservation. Retrieved from https://laws-lois.justice.gc.ca/eng/acts/m-7.01/FullText.html, Accessed October 25 2018.

Shields W. M. 1984. Factors Affecting Nest and Site Fidelity in Adirondack Barn Swallows (Hirundo rustica). The Auk, pp.780-789.

Worcester R., Titaro B., 2012. Best Management Practices for Species of Significance in Stanley Park. Stanley Park Ecology Society, 177 pages.

 

By Ariane Comeau, Conservation Technician