Abstract
A variety of gull and tern species have adapted to urban environments by nesting on rooftops and other human-made structures. Previous reports of Common Terns (Sterna hirundo) breeding on rooftops have generally involved small numbers of nests (≤25). Here, we report an occurrence of an unusually large number of Common Terns nesting on a rooftop in Port Credit, Ontario, in 2013. A complete survey of the roof was conducted on 31 May, when 1,011 Common Tern nests were counted. A similar number of breeding pairs used this roof in 2014, but the site was largely abandoned by 2015, due to management efforts to displace nesting birds. Common Terns had been observed nesting at this site (≤50 pairs/yr) since 2007; reasons for the sudden and large increase in numbers during 2013 are unclear. We attempted to relocate the colony to a nearby breakwater in 2014 and 2015, by creating artificial nesting habitat and using social attraction techniques. By 26 June 2014, 157 pairs of terns had initiated clutches at the alternate site (breeding success undocumented). The number of tern nests increased to 191 by 17 June 2015; however, all nests were depredated prior to hatching in that year, and the colony was abandoned. When rooftop colonies occur, they represent an opportunity to partner with landowners toward conservation of this declining species.
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Recommended Citation
Moore, David J.; Costa, Jeffrey N.; and Stupich, Alexis L.
(2024)
"An Unusual Case of Common Terns Nesting on a Rooftop in Ontario and an Attempt to Relocate the Colony,"
Ontario Birds: Vol. 42
:
Iss.
3
, Article 4.
Available at:
https://digitalcommons.usf.edu/ontario_birds/vol42/iss3/4