Summary1. Macroparasites may be a major factor shaping animal behaviour. Tundra ecosystems inhabited by caribou and reindeer (Rangifer tarandus) are known for large concentrations of ectoparasites including mosquitoes (Culicidae) and black flies (Simuliidae), as well as endoparasitic oestrid flies (Oestridae). 2. Increased intensity and duration of insect harassment because of climatic warming is hypothesized as a potential factor in recent declines of Rangifer across the circumpolar north. Although there is a well-observed relationship between insect harassment and caribou ⁄ reindeer behaviour, the influence of ecto-relative to endoparasitic species is unclear. Climatic changes may favour the activity patterns, distribution or abundance of certain insect species; thus, understanding differential effects on the behaviour of Rangifer is important. 3. We recorded caribou behaviour using group scan and focal sampling methods, while simultaneously trapping insects and recording weather conditions on the postcalving ⁄ summer range of the Bathurst barren-ground caribou herd in Northwest Territories and Nunavut, Canada, during 2007-2009. 4. We developed statistical model sets representing hypotheses about the effects of insects, weather, habitat ⁄ location, and date ⁄ time on caribou behaviour. We used multinomial logistic regression models to explore factors affecting the relative dominance of behaviour types within groups of caribou and fractional multinomial logistic regression models to determine factors influencing time allocation by individual caribou. We examined changes in feeding intensity using fractional logistic regression. 5. Relative dominance of insect avoidance behaviour within caribou groups and time allocation to insect avoidance by individual caribou increased when oestrid flies were present or black flies were active at moderate-high levels. Mosquito activity had relatively little effect on caribou behaviour. Time spent feeding was reduced by the greatest degree when all three insect types were present in combination. Feeding intensity was influenced to a greater extent by the accumulation of growing degree days over the course of the postcalving ⁄ summer season than by insect activity. Changes in Arctic systems that increase the activity ⁄ abundance of ecto-and endoparasites could have implications for the productivity of Rangifer populations.
Climate change is occurring at an accelerated rate in the Arctic. Insect harassment may be an important link between increased summer temperature and reduced body condition in caribou and reindeer (both Rangifer tarandus). To examine the effects of climate change at a scale relevant to Rangifer herds, we developed monitoring indices using weather to predict activity of parasitic insects across the central Arctic. During 2007-2009, we recorded weather conditions and used carbon dioxide baited traps to monitor activity of mosquitoes (Culicidae), black flies (Simuliidae), and oestrid flies (Oestridae) on the post-calving and summer range of the Bathurst barren-ground caribou (Rangifer tarandus groenlandicus) herd in Northwest Territories and Nunavut, Canada. We developed statistical models representing hypotheses about effects of weather, habitat, location, and temporal variables on insect activity. We used multinomial logistic regression to model mosquito and black fly activity, and logistic regression to model oestrid fly presence. We used information theory to select models to predict activity levels of insects. Using historical weather data, we used hindcasting to develop a chronology of insect activity on the Bathurst range from 1957 to 2008. Oestrid presence and mosquito and black fly activity levels were explained by temperature. Wind speed, light intensity, barometric pressure, relative humidity, vegetation, topography, location, time of day, and growing degree-days also affected mosquito and black fly levels. High predictive ability of all models justified the use of weather to index insect activity. Retrospective analyses indicated conditions favoring mosquito activity declined since the late 1950s, while predicted black fly and oestrid activity increased. Our indices can be used as monitoring tools to gauge potential changes in insect harassment due to climate change at scales relevant to caribou herds.
Many barren-ground caribou (Rangifer tarandus groenlandicus) populations in the Central Arctic are experiencing declin¬ ing numbers. Possible causes include conditions on the post-calving/summer range, especially harassment by biting and parasitic insects. Insect harassment alters habitat use and activity budgets of caribou, potentially leading to reduced forage intake and elevated energy expenditures. This is of particular concern as climatic warming is predicted to increase the duration and intensity of insect activity. In this study, I collected weather, insect catch, and caribou behaviour data on the summer range of the Bathurst caribou herd in the Northwest Territories/Nunavut in 2007 and 2008. I used count models within a generalized linear model framework to explore the relationship between weather parameters and insect activity. The best models, selected using Akaike's information criteria (AIC), were used to develop a correlative insectweather index applicable across the Bathurst range. Additionally, I developed models of fine-scale caribou behaviour as a function of vegetation type, phenological stage, topography, time, and insect activity. Model sets were developed for six behaviour categories, and the most parsimonious models selected using AIC. In this poster presentation, I will discuss results regarding insect indices and factors affecting fine-scale caribou behaviour (completion of analysis expected by September/October 2008). In continued work on this project, these results will be used in conjunction with GPS collar data and energetics modeling to explain patterns of movement and habitat use at coarser spatiotemporal scales, as well as to explore consequences for caribou population productivity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.