Shifts in diet, foraging effort and chick/adult condition of razorbills in coastal Newfoundland along with species interactions under varying prey availability
Abstract: Breeding seabirds respond to changes in prey availability, leading to shifts in diet, foraging effort, breeding success and possibly species interactions. Capelin (Mallotus villosus) is the primary forage fish species on the Newfoundland Shelf in eastern Canada. Capelin migrate in high abu...
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| Format: | Article in Journal/Newspaper |
| Language: | unknown |
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Underline Science Inc.
2021
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| Online Access: | https://dx.doi.org/10.48448/pdxv-dc75 https://underline.io/lecture/34696-shifts-in-diet,-foraging-effort-and-chickdashadult-condition-of-razorbills-in-coastal-newfoundland-along-with-species-interactions-under-varying-prey-availability |
| Summary: | Abstract: Breeding seabirds respond to changes in prey availability, leading to shifts in diet, foraging effort, breeding success and possibly species interactions. Capelin (Mallotus villosus) is the primary forage fish species on the Newfoundland Shelf in eastern Canada. Capelin migrate in high abundance into coastal regions to spawn during the summer, dramatically increasing inshore prey availability. Due to changes in ocean climate, however, the biomass and timing of arrival of spawning capelin has become highly variable. To investigate responses of razorbills (Alca torda) to varying prey availability, we combined ship-based measures of capelin biomass with device-based measures of foraging trip and dive characteristics (e.g., trip distance, number of dives) and colony-based measures of chick/adult body condition across three years (2017, 2019, 2020). Shifts in razorbill interactions with common murres (Uria aalge) and Atlantic puffins (Fratercula arctica) were examined by quantifying isotopic niche overlap (δ15N, δ13C) of all three species across four years (2017 - 2020). Foraging effort (e.g., trip distance, number of dives) increased in the year with lower capelin biomass (2020), which was also associated with lower adult and chick body condition. Razorbills also experienced increased isotopic niche overlap with other species in this year, due to increased species-specific niche breadth, suggesting a convergence of seabird species on a similar wider variety of alternate prey types. Findings suggest that low capelin availability during breeding will lead to increased foraging effort, fitness consequences and the potential for increased interspecific competition, which may influence the persistence and coexistence of seabird species in coastal Newfoundland. Authors: Lauren Lescure¹, Gail Davoren¹ ¹University of Manitoba |
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