Drivers of Productivity of Montane and Boreal Breeding Ducks
| dc.contributor.advisor | Clark, Robert G | |
| dc.contributor.committeeMember | Gurney, Kirsty B | |
| dc.contributor.committeeMember | Reed, Eric T | |
| dc.contributor.committeeMember | Lane, Jeffrey | |
| dc.contributor.committeeMember | Somers, Christopher | |
| dc.contributor.committeeMember | Todd, Christopher D | |
| dc.creator | Bas, Kyla E. | |
| dc.creator.orcid | 0000-0001-8849-8998 | |
| dc.date.accessioned | 2023-01-27T22:07:05Z | |
| dc.date.available | 2023-01-27T22:07:05Z | |
| dc.date.copyright | 2022 | |
| dc.date.created | 2022-12 | |
| dc.date.issued | 2023-01-27 | |
| dc.date.submitted | December 2022 | |
| dc.date.updated | 2023-01-27T22:07:05Z | |
| dc.description.abstract | Annual rates of productivity in wildlife populations are influenced by climatic and biotic factors, and offspring production and recruitment are key components of population growth in many duck species. For lesser scaup (Aythya affinis; scaup), a species of conservation concern, productivity can be particularly influential to population growth, although our understanding of factors affecting production is incomplete. I sought to identify local drivers of productivity in scaup and several other duck species by testing hypotheses related to: (i) spring phenology; (ii) local breeding-season weather; (iii) density dependence; and (iv) predator-prey dynamics. To test these hypotheses, I used long-term datasets from two distinct breeding areas: a montane site at Red Rock Lakes (RRL) Montana, USA, and a boreal site, the Yellowknife Study Area (YKSA) near Yellowknife, Northwest Territories, Canada. Ducks breeding at these sites have been studied for periods of 9 (RRL, scaup) to 26 (YKSA, multiple boreal duck species) years. I used age-corrected body masses of 5727 scaup ducklings at RRL and 26 years of annual duck pair and brood abundance counts at YKSA to assess annual variation in duckling quality (RRL) and productivity (YKSA). Age-corrected scaup duckling body mass was lower in years of both early and late spring conditions (i.e., ice-out dates) at RRL. There was no effect of the timing of spring conditions on brood abundance at YKSA. Warmer local weather conditions in the pre-nesting period were positively associated with metrics of duckling quality (RRL) and productivity (YKSA). Brood-rearing weather conditions had a small positive relationship with duckling quality at RRL, but no relationship was found with brood abundance at YKSA. I also related scaup duckling quality to the density of conspecifics at RRL. Age-corrected body mass of scaup ducklings was lower in years of higher duckling density, a pattern that is consistent with possible density dependent regulation of scaup productivity at this site. At YKSA, overall duck brood abundance increased more slowly than pair abundance (i.e. regression slope < 1:1), suggesting lower duckling production in years of higher pair density. Finally, to test effects of predator-prey dynamics on duck productivity, I related annual duck brood abundance to a small mammal index, hare density and indices of fox and lynx at YKSA. I found a non-linear relationship between brood abundance and small mammals. Furthermore, brood abundance was consistently lower when hare density was high in the current and previous years, perhaps because predators prey on species unselectively when prey abundance is high. Predator abundance indices were not strongly correlated with duck productivity, but brood abundance had a weak negative relationship with lynx abundance. My research identified several climatic and biotic mechanisms influencing productivity in ducks on breeding grounds across time and geographical range. It highlights the importance of long-term data to evaluate hypotheses at small spatial scales. | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | https://hdl.handle.net/10388/14452 | |
| dc.language.iso | en | |
| dc.subject | productivity | |
| dc.subject | ducks | |
| dc.subject | lesser scaup | |
| dc.subject | spring phenology | |
| dc.subject | density dependence | |
| dc.subject | climate | |
| dc.subject | local weather | |
| dc.subject | predator-prey community | |
| dc.subject | boreal habitat | |
| dc.subject | montane habitat | |
| dc.subject | brood abundance | |
| dc.subject | duckling mass | |
| dc.title | Drivers of Productivity of Montane and Boreal Breeding Ducks | |
| dc.type | Thesis | |
| dc.type.material | text | |
| thesis.degree.department | Biology | |
| thesis.degree.discipline | Biology | |
| thesis.degree.grantor | University of Saskatchewan | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science (M.Sc.) |