Ecology Abstracts

Radar-based bird detection in the Alberta Oil Sands

Sarah Loots, M.Sc.

Radar is used to detect approaching birds by all oil sands operators at their tailings ponds in northern Alberta. Upon detection, radar software systems deploy bird deterrents. We aim to identify the landscape and ecological conditions that most affect radar performance, particularly those that operators can control. We used two independent X-band radar systems, each with a different antenna (parabolic and open array), and the open-source software radR to measure bird detection over water. We compared the data from both radars with information generated by human observers. The rates of false positives and false negatives for birds in the air differed for each radar system under various landscape and ecological conditions. The overlap between radar and human observers was surprisingly small, with targets missed by both. Neither radar system was able to detect birds once they were landed on the surface of a pond, though they were able to detect birds flying low over the water surface. The analysis for this research is ongoing, and we will identify landscape features and ecological conditions that affected the sensitivity and specificity of radar-based bird detection. These recommendations will be relevant to all industries, governments, and consultants doing radar-based bird detection or monitoring.


Demonstration of pheromone-mediated communication disruption for Coleophora deauratella (Lepidoptera: Coleophoridae)

Boyd Mori, Ph.D.

The red clover casebearer (RCC), Coleophora deauratella (Lepidoptera: Coleophoridae), is an invasive seed predator of red clover, Trifolium pratense, throughout the Peace Region of Alberta. In clover seed production areas throughout Canada, RCC infestations can cause > 80% seed loss. Insecticides have proven ineffective against RCC as the cost of application is not offset by increased seed yield. Lack of insecticidal control options makes RCC an ideal candidate for pheromone-mediated communication disruption. Previous experiments determined that RCC trap capture can be significantly reduced with both pheromone puffer and twist-tie dispenser treated plots. Here, we conducted field studies with pheromone twist-tie dispensers (Shin-Etsu, Japan) in an effort to optimize and understand how pheromone-mediated communication disruption acts on this pest. Pheromone twist-tie dispensers containing the full pheromone blend (10:1 ratio of Z-7-dodecenyl acetate and Z-5-dodecenyl acetate) or major component only (Z-7-dodecenyl acetate) were placed in small plot trials to determine the mechanism by which communication disruption acts. As well, pheromone twist-tie dispenser density and dose was varied in order to optimize pheromone-mediated communication disruption. The methods used during these field studies can be combined into an integrated pest management program to potentially mitigate the current RCC outbreak.


Changes in coyote diet over a large-scale gradient of urbanization

Maureen Murray, Ph.D

The coyote is a generalist and opportunistic carnivore that has expanded its range throughout North America and into many major cities. To fully understand the success of urban adapters like coyotes, more work is needed to clarify what changes in diet facilitate adaptation to areas with human disturbance. We used meta-analyses to study coyote diet in urban, semi-agricultural, and non-urban areas across Alberta. We analyzed 2,505 coyote scats for the occurrence of mammalian prey, fruit, domestic pets, and anthropogenic refuse, seasonal variability and diet diversity. Small mammals were the most important items across all study locations. However, lagomorphs (Lepus spp.), fruit, and anthropogenic refuse were significantly more abundant and ungulates were significantly less abundant in urban centres than in non-urban areas. Coyote diet was more diverse in urban centres and diversity, along with consumption of refuse and pets, appeared to increase during winter months in urban areas when natural foods may be less available. Coyotes thus appear to thrive in urban areas by eating a variety of food types, including anthropogenic refuse, to supplement natural foraging. The results of study will provide valuable information on the adaptive behaviour of coyotes and other urban adapters such as red foxes and raccoons.


Sexual Size Dimorphism and Rensch’s Rule in Feather Mites (Acari: Astigmata): Consistently Inconsistent

Kaylee Byers, M.Sc.

Sexual size dimorphism (SSD) is widespread throughout animals. Rensch’s rule predicts that dimorphism between the sexes will increase with body size in taxa where males are the larger sex and decrease with body size in taxa where females are larger. I tested this relationship in eight families of feather mites (Acari: Astigmata) by regressing log transformed male length over log transformed female length measurements and looking for a slope significantly less than 1.0. Support for Rensch’s rule was found in six of the eight families (Analginae: Analgidae, Dermationidae, Psoroptoididae, Pterodectinae: Proctophyllodidae and Syringobiidae) and in the combined analysis of all mites. Allometric trends were not consistent for mites occupying similar habitats on the host (ie. skin, feather vanes, down, quills). These results refute assertions of the generality of Rensch’s rule across taxa. Future analyses should consider genitalic length as a component of SSD and should also incorporate phylogeny to remove phylogenetic bias.


Evaluating fish habitat compensation in the Canadian Arctic

Andrea Erwin, M.Sc.

Resource development is expanding in Canada, particularly in the Arctic. A habitat compensation project focused on small Barrnland lakes and their outlet streams is underway for the Lac de Gras, NWT watershed as a result of diamond mine development. The goal of the compensation is to improve ecological connectivity within a small 3-lake, 3-stream ecosystem. Our research project is assessing ecosystem functioning before and after the compensation efforts and thereby the effectiveness of the fish habitat compensation. My research goal is to use baseline biotic and abiotic habitat data collected over 3 field seasons (2009-2011), and post-compensation data collected in 2012 (continuing in 2013), to assess stream community composition and ecosystem functioning using a Before-After-Control-Impact (BACI) design. I am addressing the following research questions: 1) How will stream habitat attributes and their functions change after compensation? 2) Will macroinvertebrate communities in these Arctic streams re-establish their natural (pre-compensation) state within the first two post-compensation years? If not, how do macroinvertebrate abundance, biomass, and species composition change after compensation activities? To help me address my research goals, I will quantify stream macroinvertebrate communities and fish habitat features and compare them to pre-compensation communities and conditions and to undisturbed reference streams.


Landscape Influences on Survival of Post-fledging Ferruginous Hawk (Buteo regalis)

Melynda Johnson, M.Sc.

Increasing pressure from development and conversion of native rangeland into cropland contribute to habitat loss and degradation for many species. Ferruginous Hawks (Buteo regalis) (FEHA) have experienced significant population declines and have recently been uplisted to threatened nationally, endangered in Alberta, and apparently secure (S4) in Saskatchewan. Although various factors including habitat alteration have been linked to population trends, the post-fledging period is often not understood nor considered when developing recovery and management plans for avian species, even though this period exhibits high mortality rates, and understanding factors that influence juvenile survival could be a key component in reversing declines. Therefore, in 2011 and 2012, I tracked a total of 101 hawks to determine if the composition of landscape features (including agricultural-use type, road density and electrical powerline density) can predict areas of high mortality risk for juvenile FEHA. Landscape composition around nest sites and morphometric features of fledgling hawks were analyzed as indices of parental care, to determine if these variables predict mortality. Preliminary analyses indicate mortality rate for juveniles was 36% and most of the mortalities occurred within 3km of the nest. Mortality rates were highest in native rangeland and cropland with main causes including predation (Great-horned Owls (Bubo virginianus) and coyote (Canis latrans)), vehicle strikes, starvation and probable powerline collisions. My study suggests that juvenile mortality is correlated with human activities and the placement of industrial features and artificial platforms on the landscape may mitigate juvenile FEHA mortality rates.


Warming amplifies invasive predator effects in sentinel ecosystems of global change

Megan MacLennan, Ph.D.

Mountain lakes are sentinel ecosystems of global change. Extreme warming events increasingly affect these ecosystems, in which invasive fish have already eliminated keystone species. Stressors often mediate the effect of each other to generate non-additive “ecological surprises” and forecasts of the combined impact of invasive fish and warming are hindered by uncertainty surrounding their potential interaction. Further, their net effect may depend on the order in which they are exposed to the community. We hypothesized that invasive fish and warming would interactively affect naturally fishless lake communities because both stressors favour small species but that stressor order would influence their combined impact. To test these hypotheses, I performed a 42-day outdoor mesocosm (1000-L) experiment in which five fishless lake communities were each exposed to non-native trout (F) and/or warming (W) in six treatment combinations: an unstressed control, two sequential exposures (F then W, W then F), two single-stressor exposures (F, W) and one simultaneous exposure (FW). Stressor effects were highly asymmetric; invasive fish predation strongly favoured small species while warming exerted no independent effect. However, warming interactively increased the biomass of small species favoured by fish. Consequently, length of simultaneous exposure to stressors, not stressor order, drove their net effect.


Spring hyperphagia in polar bears: What brings the food to the table?

Nicholas Pilfold, Ph.D.

Predators seek settings that maximize the vulnerability of their prey, whether spatial, temporal or behavioural. Polar bears (Ursus maritimus) of the Beaufort Sea enter an intensified feeding period in spring and gain fat reserves to survive periods of low prey availability. Employing opportunistic observations of seals killed by polar bears (n = 650) and hunting attempts on ringed seal (Pusa hispida) lairs (n = 1396), I examined proximate mechanisms of polar bear hyperphagia. In this talk, I will provide evidence on the spatial, temporal and behavioural factors that set in motion hyperphagia in polar bears.


Beaver canals provide movement corridors for post-metamorphic wood frogs

Nils Anderson, M.Sc.

Beavers (Castor canadensis) are well known as ecosystem engineers, and although they are best known for creating ponds by damming streams, beavers are also capable of modifying existing wetlands in other ways. In wetlands with soft substrates and shallow banks, beavers commonly dig extensive networks of foraging canals towards nearby forest cover. Such moist movement corridors can be attractive to amphibians, such as the wood frog (Lithobates sylvaticus). From late July to the end of August, 2011 and 2012, we used visual transect surveys and drift fences to study habitat use by YOY wood frogs around beaver modified ponds in Miquelon Lake Provincial Park (in the dry mixed-wood boreal forest of east central Alberta). Relative abundance of YOY wood frogs was higher on beaver canals than on shorelines unmodified by beavers. On drift fences, the number of frog encounters was highest at the beaver canal, and declined with distance from the canal. Beaver canals commonly exceed 200 m in length, and YOY wood frogs rarely disperse more than 400 m from their natal pond before overwintering for the first time. By aiding the dispersal of YOY wood frogs, beaver canals provide an important linkage between aquatic and terrestrial environments.


Sympatric polymorphism in lake trout: the coexistence of multiple shallow-water morphotypes in Great Bear Lake

Louise Chavarie, Ph.D.

Intraspecific morphological variation, ranging from subtle to large enough to result in misidentification, is commonly observed among fishes in recently glaciated lakes of the Canadian Arctic. A UPGMA cluster analysis of 558 Lake Trout distinguished three different morphs that co-exist in the shallow waters of Great Bear Lake, NT. A fourth distinct albeit rarer morph has also been identified from other collections. We combined classical morphometric/meristic measures with shape analysis (geometric morphometrics) to quantify morphological differences among adult and juvenile shallow-water Lake Trout from Great Bear Lake. The most important differences among adult morphotypes are associated with variation in head and fin measurements, whereas body shape variation is less distinctive. These patterns are consistent with many evolutionary adaptations in fish that involve traits associated with feeding and swimming. However, no consistent patterns of variation were found among juveniles, suggesting that divergence develops at later stage. Due to the large size and complex morphometry of Great Bear Lake, we also examined to determine patterns across different regions of the lake. Within a single morphotype, morphological variation, including body shape differences, was found to vary among lake areas. This unusual endemic diversity challenges prevailing ideas that Lake Trout forms are segregated primarily by depth and have a low degree of phenotypic variation compared to their congeneric relatives, especially Arctic Char. Although the deep-water habitats of Great Bear Lake have not been well studied, additional morphotype are possible such that the Lake Trout of Great Bear Lake could challenge the iconic diversity of Arctic Char by equaling or exceeding the number of morphotypes found within a single system.


An assessment of closed population abundance estimates from program MARK using a censused wild population.

Kristin Van Katwyk, M.Sc.

Knowledge of population size is often required for monitoring rare species, forming harvest quotas, and evaluating management strategies. A complete enumeration of a population for these purposes is rarely possible and has motivated the development of user-friendly abundance estimation programs. Despite being widely available for over forty years such programs have seldom been validated outside of computer simulation and enclosure studies. In this study we compare abundance estimates, calculated from 35 mark-recapture trapping sessions in program MARK, against a complete census of a well-documented wild population of North American red squirrels (Tamiasciurus hudsonicus) in the Yukon Territory. Precision, relative bias, and confidence interval coverage were calculated for the evaluation of closed population mark-recapture estimates. We found most estimates were positively biased, which could have significant repercussions for wildlife management strategies. High capture probabilities were confirmed to greatly reduce variance of estimates, but estimates converged with minimum number alive, not necessarily number of censused individuals. Due to the highly documented nature of this population we were able to provide biological insight into estimate error. This research utilizes a censused wild population to provide a strong assessment of strengths and weaknesses in this commonly implemented program.


Can demosponges respond behaviourally to increased ambient currents? Testing passive flow in three temperate demosponges

Danielle Ludeman, M.Sc.

Sponges are suspension feeders that process up to 900x their body volume in water daily with up to 98% efficiency, and have long been considered to take advantage of passive flow to reduce the cost of pumping for filtration. It is unclear, however, whether all sponges a) need to use passive flow, and b) are able to use passive flow. Demosponges have a fine canal system with high resistance to water flow. Mathematical models predict that passive flow does not occur in these sponges, but instead their food-rich temperate waters provide enough energy to sustain maintenance and growth despite the high cost of pumping. We studied excurrent filtration rates and oxygen consumption during ambient flows of 0-20cm/s in three temperate demosponges, using particle imaging velocimetry, profiling acoustic Doppler velocimeters, and an oxygen optode. We found that excurrent velocities increased with increasing ambient flows, with no change in oxygen drawdown meaning no additional energy was expended to pump during increased ambient flow. This suggests that demoponges can take advantage of passive flow despite the high resistance to water flow in their canal system.


The Influence of Landcover and Industrial Development on Ferruginous Hawk Reproductive Success

Janet Ng, Ph.D.

Ferruginous hawks (Buteo regalis) are considered highly dependent on grasslands and negatively affected by human disturbance, yet they are found nesting in areas with high proportions of cropland and near roads, oil and gas wells, and other industrial infrastructure. Comparative reproductive success between natural and developed areas is unknown and understanding the effects of landcover and energy sector development is important because they are dominant land uses in southern Alberta and Saskatchewan. Development may result in habitat loss and degradation, which may threaten this species at risk by potentially reducing reproductive output. While grassland conversion to cropland has stabilized in Canada, energy sector development continues to increase and the related industrial infrastructure, such as wells, roads, and power lines, can alter habitat quality for ferruginous hawks. Our objective is to determine the influence of landcover and energy sector development on ferruginous hawk nesting success. In 2010-2012, we monitored ~400 nests with 0% to 100% native prairie in the surrounding landscape. Within this gradient, we also monitored nests that were in high versus low oil and gas density. We monitored the fate of each nest, sources of nest mortality, reproductive output (number of young fledged), and daily nest survival. We will compare these reproductive parameters across the gradients of landcover and industrial development and determine how they may influence reproduction. Comparing reproductive performance between natural and developed areas is essential to understanding how agricultural conversion and industrial development may affect species conservation and recovery.