Environmental and Life Sciences

Due to climate change and managed care, birds may face interacting effects of novel diets and environmental temperatures. I examined how captive zebra finches (Taeniopygia guttata) responded to a 6-month acclimation to either thermoneutral or cool temperatures when provided with saturated or unsaturated fatty acid enriched diets. Body mass was lower on the unsaturated fatty acid diet, but only in cool conditions. Individuals in cool temperatures and saturated fatty acid enriched diets had heavier organs, but pectoralis mass and metabolic rate did not display an effect of diet. While birds on each treatments illustrated similar initial increases in plasma fatty acid unsaturation, composition and concentration of constituent fatty acid varied based on their diet and temperature. Individuals on the unsaturated fatty acid enriched diet and cool treatments had lower survivorship. Collectively, my research will allow researchers to better predict how birds will be impacted by shifting or novel environments.

Author Keywords: chronic acclimation, fatty acids, metabolic rate, Taeniopygia guttata, temperature, unsaturation

Quantifying the impacts of environmental conditions on the abundance of wildlife populations is important for making informed management decisions in the face of increasing environmental threats. Managers require robust tools to estimate abundance and density of wildlife rapidly and with precision. Within the context of studying white-tailed deer, I evaluated the use of camera-traps and a recently developed spatial-mark resight model to estimate deer density and evaluate habitat and land use factors influencing deer density. The study was conducted in central Ontario, Canada on approximately 16 km2 of public land including the protected Peterborough Crown Game Preserve. Telemetry locations from 39 radio-collared deer were used and one hundred camera-traps were deployed for a total of 140 days from January 2022 to May 2022. Using telemetry locations and camera-trap photos I built a two-step spatial-mark resight model to estimate deer density. Deer density varied during the study as a portion of the population migrated to wintering areas outside of the study area. Despite fluctuations in precision, estimates improved towards the end of the study as more data became available and deer space use stabilized. The average deer density during the entire study was 3.0 deer/km2 (95% CI= 0.1, 5.8; SD= 1.7; CV= 55%; N= 238 deer). The lowest mean density was 0.2 deer/km2 (95% CI= 0.1, 0.4; SD= 0.1; CV= 50%; N= 15 deer) from February 26th to March 11th and the highest mean density was 4.8 deer/km2 (95% CI= 3.1, 6.2; SD= 0.8; CV= 17%; N= 378 deer) from May 7th to May 20th. When I incorporated spatial covariates into the model to estimate effects on deer density, higher proportions of mixed forest, deciduous forest, and road and trail density all had negative effects on deer density. While models contained some uncertainty, deer density appeared higher in the portion of the study area protected from licensed hunting. This thesis provides a framework for managers to use camera-traps and the spatial-mark resight model to monitor deer populations and link environmental covariates to spatial variation in density. As environmental threats such as habitat loss and infectious diseases increase in severity, monitoring wildlife population numbers will be vital for informed responses to these threats. The two-step spatial-mark resight model with environmental covariates provides managers with a long-term monitoring tool to evaluate management efforts and population health in forested areas.

Author Keywords: camera-trap, chronic wasting disease, landscape ecology, spatial-capture recapture, white-tailed deer, wildlife management

The Lesser Yellowlegs (Tringa flavipes) is a steeply declining shorebird that breeds across boreal North America. I studied nest survival in Anchorage, Alaska, USA and Churchill, Manitoba, Canada and nest site selection factors in Churchill. Nests were monitored at each site and daily nest survival rates (DSR) were calculated based on a maximum likelihood approach. Overall nest survival was ~63% for Anchorage (lcl–ucl = 0.450–0.773, n=49) and ~28% (lcl–ucl = 0.113–0.481, n=26) for Churchill. Earlier initiation dates, warmer mid-incubation temperatures and lower temperature variability during nesting were linked with higher DSR. I tested nest site selection at territorial and microhabitat scales using multiple logistic regression to compare nest sites with random points. Lesser Yellowlegs selected territories further from water and, at the microhabitat scale, taller shrubs. Projected climate-related shifts in weather and habitat will likely present both benefits and challenges to Lesser Yellowlegs.

Keywords: Lesser Yellowlegs, Tringa flavipes, shorebird, nest survival, nest success, nesting habitat, breeding habitat, boreal, sub-arctic, climate change, Anchorage, Alaska, Churchill, Manitoba

Author Keywords: boreal, breeding habitat, Lesser Yellowlegs, nest survival, shorebird, Tringa flavipes

I used 31 years of Semipalmated Plover (Charadrius semipalmatus) population data to assess the effects of vital rates on a local breeding population of plovers in Churchill, Manitoba, Canada. I used three similar Bayesian Integrated Population Models (IPMs), with the last a coupled IPM population viability analysis (PVA) approach to predict the impact of changing spring temperatures on future population size. I estimated adult and juvenile apparent survival, fecundity, immigration rate, and yearly population size estimates, and I found that population growth rate was most highly correlated with immigration and adult apparent survival. Moreover, I found that the population remained relatively stationary with a slight decline in recent years. I also found a significant positive effect of spring average daily minimum temperature on juvenile apparent survival. I used this effect to inform my PVA and to evaluate the risk of quasi-extinction for 20 years after the end of the study. I found a low quasi-extinction risk and a greater probability of the population increasing in the next twenty years when informed by predicted spring temperatures from global climate models. My findings suggest some resilience of this species to one effect of climate change and emphasize the importance of continued monitoring to assess if declines in this species will change as multiple threats to their existence in the sub-arctic progress.

Author Keywords: Bayesian, Climate change, Integrated population model, Population dynamics, Population viability, Semipalmated Plover

In this study, twenty lake catchments surrounding Iqaluit, Baffin Island, were assessed for trace element concentrations (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, THg, V, Zn) in lake water, catchment soil, lake sediment, and moss (Hylocomium splendens). Additionally, the sources of each trace element were determined through the positive matrix factorization (PMF) model and enrichment factors (only in moss). Geogenic trace elements had the highest median concentrations (Fe>Al>Mn) throughout the study media and across the study catchments. Anthropogenic trace elements had the lowest median concentrations (Pb>As>Cd>THg) across the lake catchments, which were generally several orders of magnitude lower compared to geogenic elements. The PMF model identified trace elements associated with geogenic or anthropogenic sources, i.e., THg (47%), Cd (40%), Zn (34%), and Al (27%) were identified as originating from industrial emission sources deposited onto lakes because they accounted for a large proportion within the model.

Author Keywords: Arctic lake catchments, Biomonitoring, Enrichment factors, Positive matrix factorization model, Trace elements, Water chemistry

Globally, fledglings of more than 50 seabird species are vulnerable to stranding in human settlements near their colonies as they leave their nests for the first time. This phenomenon has been attributed to attraction toward and disorientation by artificial light at night (ALAN). Grassroots rescue programs find more birds in illuminated locations than in dark ones, but it is unclear to what extent this pattern is driven by seabird versus rescuer behaviour. I studied behavioural responses to ALAN in stranding-prone Atlantic puffin (Fratercula arctica) and Leach's storm-petrel (Hydrobates leucorhous) fledglings and investigated detection probabilities of 3D-printed puffin fledgling decoys by rescuers. I hypothesized that seabird strandings are due to attraction toward ALAN; that post-stranding behaviour varies with taxon and lighting conditions; and that post-stranding behaviour (e.g., concealment) and lighting conditions drive variance in detection probability of stranded seabirds by rescuers. To address my first hypothesis, I alternately illuminated two beaches near a Newfoundland puffin colony and found significantly more puffin fledglings stranded when the beaches were illuminated than when they were dark, supporting the light attraction hypothesis. Stranded puffins similarly moved toward light over darkness in a Y-maze choice experiment and were less active under LED light than in darkness or under high-pressure sodium light, demonstrating a preference toward certain light conditions post-stranding. In contrast, storm-petrels predominantly avoided lit conditions in a Y-maze and were less active in darkness than under light. Further, when provided with a place to hide, more than half of storm-petrels concealed themselves when in light conditions versus none in darkness. To test my third hypothesis, I deployed puffin decoys and found that rescuers detected them more easily in higher light levels, in less concealed locations, and with increased search effort. My results support historical deductions that seabird fledgling strandings are caused by attraction toward artificial light but demonstrate that post-stranding behavioural responses to ALAN depend on species and light type, which may in turn affect detection probability by rescuers.

Author Keywords: artificial light, atlantic puffin, charadriiform, Leach's storm-petrel, light attraction, procellariiform

This study examines the atmospheric (synoptic) controls on snowmelt and snow-free season carbon dioxide (CO2) fluxes at Daring Lake, Northwest Territories. Atmospheric circulation patterns were derived from 500 hPa geopotential height and classified using the self-organizing maps artificial neural network. Snowmelt timing was not found to be influenced by atmospheric circulation patterns or large-scale teleconnection indices, but a shift from meridional to zonal atmospheric circulation marked the transition from pre-melt to melt period. Multiple linear regression identified heating degree days and incoming solar radiation as the most important meteorological predictors of melt length; however, the model would have benefitted from additional variables. Analysis of CO2 (net ecosystem exchange, NEE) during the snow-free season highlighted a strong correlation between NEE and temperature anomalies. Like the snowmelt period, no atmospheric circulation patterns were found to significantly influence NEE; however, these findings prompt further questions regarding snowmelt and CO2 fluxes in the Canadian low Arctic.

Author Keywords: atmospheric circulation, carbon fluxes, net ecosystem exchange, self-organizing maps, snowmelt, synoptic patterns

Climate change affects birds' reproductive ecology by altering breeding timing, distribution, and habitat suitability. Snowmelt patterns complicate these changes affecting habitat availability and suitability for birds and their arthropod prey. Snow varies as a function of both large-scale climate patterns and local-scale topography. I used elevational gradients as a proxy for local- scale snow impacts, investigating how elevation affects arthropod abundance, and nest placement, initiation, fate, and habitat for Lapland Longspur (Calcarius lapponicus) and Semipalmated Sandpiper (Calidris pusilla) north of Baker Lake, Nunavut. I found and monitored nests over multiple breeding seasons and used pitfall traps and conducted vegetation surveys. Results show that elevation significantly affects arthropod biomass and nest placement, but not nest initiation or success. Both species preferentially nested at lower elevations with higher arthropod biomass. Thus, birds in the central Arctic choose nesting sites at lower elevations with better food availability rather than higher elevations with earlier snowmelt.

Author Keywords: Arctic, arthropod biomass, Lapland Longspur, nest site selection, nest success, Semipalmated Sandpiper

Animal migrations are ubiquitous and one of the most threatened ecological processes globally. Because of the multifaceted nature of migration – seasonal movements between home ranges – it can be difficult to tease apart the underlying mechanisms influencing this behaviour. It is necessary to understand these mechanisms, not only to deepen our fundamental understanding of migration in animals, but also because migrations in many species are vulnerable to environmental change. In Chapter 2, I first systematically identify the broad proximate drivers of migration and offer generalities across vertebrate taxa. I quantitatively reviewed 45 studies and extracted 132 observations of effect sizes for internal and external proximate drivers that influenced migration propensity. Through this meta-analysis, I found that internal and external drivers had a medium and large effect, respectively, on migration propensity. Predator abundance and predation risk had a large effect on migration propensity, as did individual behaviour. Of the studies that examined genetic divergence between migrant and resident populations, 64% found some genetic divergence between groups. In Chapter 3, I explore the genetic basis for migration and identified genes associated with migration direction from pooled genome-wide scans on a population of 233 migrating female mule deer (Odocoileus hemionus) where I identified genomic regions including FITM1, a gene linked to the formation of lipids, and DPPA3, a gene linked to epigenetic modifications of the maternal line. These results are consistent with the underlying genetic basis for a migratory trait which contributes to the additive genetic variance influencing migratory behaviours and can affect the adaptive potential of a species. Finally, in Chapter 4 I used a pedigree-free quantitative genetic approach to estimate heritability and sources of environmental variation in migration distance, timing, and movement rate of the same population of mule deer. I found low heritability for broad patterns of migration timing, and greater variation in heritability for behaviours during migration, with low heritability for distance and duration and high heritability for movement rate along the route. Insights into the genetic and environmental sources of variation for migration are critical both for the eco-evolutionary dynamics of migration behaviour, and for the conservation of species whose migrations may be vulnerable to environmental change. My thesis reveals that broad patterns of migration are driven largely by environmental effects while within these broad patterns, migration behaviour is driven to a measurable degree by genetic variation.

Author Keywords: heritability, migration, Odocoileus hemionus, reduced representation sequencing, whole genome sequencing

Many species of shorebirds depend on stopover sites to rest and refuel during their long-distance migrations. To determine how shorebirds use migratory stopover sites, we tracked three species of shorebirds at two stopover sites in British Columbia, Canada from 2018-2021 during northward and southward migration using automated telemetry. Western Sandpipers (Calidris mauri) stayed longer at the Fraser River Estuary (4-8 days) compared to Tofino (2-6 days). We assessed habitat use of Sanderlings (Calidris alba), Semipalmated Plovers (Charadrius semipalmatus), and Western Sandpipers between beaches and mudflat at the Tofino stopover site. Time spent at the beach and mudflat habitats varied by species, tidal period, time of day, migration period, and human disturbance. This study shows that different stopover sites, and habitats within stopover sites, offer a unique set of characteristics used by birds exhibiting varying migration strategies, highlighting the importance of conserving a diversity of migration stopover locations and habitats.

Author Keywords: habitat use, human disturbance, length of stay, migration, shorebird, stopover site