Abstract
During 16 of 21 consecutive annual breeding seasons, two diseases, Newcastle disease and avian cholera, killed approximately 50% of juvenile Double-crested Cormorants (Phalacrocorax auritus) in a large nesting colony in Canada. From 1994 to 2014, we recorded data annually on disease occurrence, causal pathogens, species and age classes affected, total number of breeding pairs of cormorants on the colony site, and other biological parameters. A mathematical model of pathogen transmission was constructed to assess the potential importance of transmission parameters and to test a hypothesis regarding the potential effect of the observed progressive loss of nest trees and the consequent shift from tree-nesting to ground-nesting behavior. The model indicated that juveniles from ground nests were 14 times more likely to die from epidemic disease (50.14% mortality) than were juveniles from nests in trees (3.57% mortality). Additive disease-related mortality of juvenile cormorants in the observed range of 40–60% would reduce a closed cormorant population over time. There was no directional change in the colony population during the study period, suggesting that immigration had compensated for disease-related mortality. Our results highlight the preeminent influence of environmental factors on pathogen transmission and the value of long-term data sets.
| Original language | English |
|---|---|
| Pages (from-to) | 773-783 |
| Number of pages | 11 |
| Journal | Journal of Wildlife Diseases |
| Volume | 57 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 11 Oct 2021 |
Bibliographical note
Funding Information:This research was carried out under annual scientific permits for wildlife research issued by the Government of Saskatchewan. Funding was provided by the Canadian Wildlife Health Cooperative, with additional contributions from Sas-katchewan Environment and Resource Management; Canadian Food Inspection Agency; Canadian Wildlife Service; Wildlife Health Fund of the Western College of Veterinary Medicine; Animal Health Trust of Canada; Alberta Sports, Recreation, Parks and Wildlife Foundation; and the University of Saskatchewan. Parks Canada Agency provided aerial photographs. Technical and logistical support were provided by Ian Shirley, Marnie Zimmer, Gary Wobeser, Alex Reid, Ferdie Edquist, Ron Lalibert?, Rhys Beaulieu, Charlene Berkvens, Asha Perera, Kamal Gabadage, Seth Cherry, Dan Frandsen, Dustin Guedo, Derek Harder, Fiona Moreland, E. Jane Parmley, Chris Somers, Theresa Stene, and many volunteers.
Publisher Copyright:
© Wildlife Disease Association 2021.
