E-Thesis 18 views 2 downloads
The demographic role and drivers of crash mortality in nesting seabirds / STEFAN BARNETT
Swansea University Author: STEFAN BARNETT
Abstract
Recent research suggests that animals adjust their space-use to minimise their chance of accidents, such as slips or collisions. The consequences of such accidents should be particularly severe in flying animals, but examples of collisions in natural scenarios remain rare. Regular crashes have been d...
| Published: |
Swansea
2026
|
|---|---|
| Institution: | Swansea University |
| Degree level: | Master of Research |
| Degree name: | MRes |
| Supervisor: | Bull, J., and Shepard, E. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa71897 |
| Abstract: |
Recent research suggests that animals adjust their space-use to minimise their chance of accidents, such as slips or collisions. The consequences of such accidents should be particularly severe in flying animals, but examples of collisions in natural scenarios remain rare. Regular crashes have been documented in a population of northern gannets breeding on Ailsa Craig. In this study I use a dataset of crashes recorded each month over three consecutive years, along with reanalysis data, to investigate the environmental drivers of gannet crashes and assess their demographic consequences. I combined statistical and demographic approaches to address three questions: (1) can environmental factors predict crash events, (2) what are the consequences of crash mortality for population growth rates, and (3) how might shifting wind regimes influence long-term population trajectories? Quasibinomial generalized linear models were used to test environmental predictors of crash events, while matrix population models were used to project population dynamics. Outputs from statistical models were integrated into matrix population models by adjusting adult survival transitions. Wind direction emerged as the sole significant predictor of crashes, with the probability of crashes increasing in north-westerly winds and decreasing with south-easterlies. Crash mortality accounted for 5.4% of annual adult mortality. Removing this mortality led to increases in projected population sizes of 11.3% and 23.9% over 25 and 50 years, respectively.Incorporating wind-driven crash probabilities into demographic models revealed the full envelope of population responses that would be possible under changing wind regimes.These findings identify accident mortality as a novel, demographic, non-anthropogenic pressure in a long-lived seabird. Shifting wind regimes may influence seabird populations by altering habitat suitability and modifying the landscape of risk around colonies, thereby broadening our understanding of how environmental variability shapes avian population dynamics. |
|---|---|
| Keywords: |
Professor James Bull, Professor Emily Shepard |
| College: |
Faculty of Science and Engineering |