Friday Philosophicals run most Fridays in Kresge 103 (check the schedule). Seminars start at 3:30 pm and are expected to end by 4:20 pm.
December 6, 2019
Chemosignaling is likely important for avian mate choice but has been understudied due to the misconception that olfaction is unimportant in birds. The major histocompatibility complex (MHC) is an important immune gene region, and selection should favour the ability to assess potential mates’ MHC genotype. Preen oil is the leading candidate source for compounds involved in avian chemosignaling. I tested the hypothesis that preen oil is a reproductive chemosignal, using gas chromatography to test for differences in the preen oil composition of song sparrows (Melospiza melodia) from different populations, breeding vs nonbreeding season, adults vs juveniles, and males vs females. Then, I used behavioural trials to test whether birds discriminate between preen oil odour from same sex vs no odour, same vs opposite sex, heterospecific vs no odour, and from MHC-similar vs MHC-dissimilar potential mates. My findings suggest that chemical communication and odour-based MHC assessment is taxonomically widespread.
Litterfall is a major input of carbon and mercury (Hg) into forest soils but the controls governing the release of Hg from litter to soil are poorly understood. A mesocosm experiment with coniferous and deciduous litters examined the transfer of Hg from litter to soil. Soil porewater was sampled for carbon quality analysis, dissolved organic carbon (DOC) content, and total Hg. Carbon to nitrogen ratios of both litters decreased over time, while the porewater showed a shift in carbon quality corresponding with decomposition and leaching. Mercury in porewater from deciduous litter peaked halfway, coinciding with a peak in DOC. Taken together this suggests that Hg released is a function of decomposition. Understanding the controls of decomposition on Hg storage and release in forest soils will contribute to better predictions of recovery timing in contaminated watersheds and how climate change will impact mercury cycling.
November 29, 2019
Individuals in many animal species show consistent variation in activity and movement, suggesting the existence of behavioural syndromes. Accordingly, behaviours related to movement on multiple scales, such as exploration and migration distance, may be correlated. I assessed the relationship between exploratory behaviour and migration distance in a population of song sparrows (Melospiza melodia) using a novel environment test to quantify exploration and stable isotope analysis of claw samples to infer latitudinal migration distance. Exploration levels were positively related to latitudinal migration distance. I discuss mechanisms that may drive this relationship, including circulating androgen levels and sequence variation in the dopamine receptor gene DRD4. The observed relationship between small-scale movement (exploration) and larger-scale movement (migration) suggests the existence of a behavioural syndrome involving the two movement behaviours and provides insight into the evolution and consequences of movements over multiple geographic scales
Lake Huron currently supports a predatory fish community that is predominately composed of four species of salmonids. The native lake trout (Salvelinus namaycush), and the introduced: chinook salmon (Oncorhynchus tshawtscha), rainbow trout (Oncorhynchus mykiss), and coho salmon (Oncorhynchus kisutch). Since 1994 there has been a steady decrease in the biomass of prey fish of these salmonids. By the end of 2003 the alewife (Alosa pseudoharegus) population crashed, imposing a major nutritional stress on Lake Huron’s salmonids. Few studies have focussed on determining the effects of this nutritional stress on the diets of these predatory fishes. As such, the objective of this study is to compare the diets of salmon before and after the 2003 alewife population crash. Stable isotope analysis will be conducted on archival scale samples of salmon collected prior to 2003 and compared to scale samples collected between 2019-2020.
November 22, 2019
Today’s migratory birds navigate a perilous human-modified landscape. To survive passage through unfamiliar urban spaces, birds must avoid many artificial obstacles they cannot see. Collisions with glass windows thus represent a major anthropogenic source of avian mortality. Given recent declines in bird populations, consumers, conservationists and policymakers require tools to mitigate the risk of bird collisions at new and existing construction with glass. Deterrent technology that can prevent birds from hitting windows is urgently needed. However, little is known about how birds see glass and glass treatments, and the efficacy of existing deterrent products is unclear. My objectives are: 1) apply visual perceptual modelling to study how birds see windows; 2) develop a standardizable behavioural assay to test responses of live birds to glass types and glass treatments under semi-natural conditions. This research will produce empirical data to justify the design of collision deterrents which cater to avian visual sensitivities.
Humans kill everything. Our unique ecology to kill any animal affects the behaviour of wildlife worldwide. Recent research on a handful of mammals has demonstrated that humans may be more frightening than non-human predators, but it remains to be experimentally tested whether this fear of us pervades whole communities of mammals. My objective is to comprehensively test whether and how fear of humans affects the behaviour of a mammal community in South Africa’s Kruger National Park. I used a newly developed technology, the Automatic Behavioural Response system, to video record the responses of wildlife to five playback treatments. South African mammals are not afraid of birds, but are afraid of lions, allowing me to gauge whether wildlife fear humans more or less than the top large carnivore. Human sounds included speaking and sounds associated with hunting: gunshots and dogs. I am currently quantifying the fear responses of 30 mammal species.
October 25, 2019
Peatlands are important wetland systems, but dominant macroarthropod groups endemic to peatlands and the environmental factors that affect them are poorly represented in the literature. I examined the richness, abundance, and community composition of soil and surface dwelling macroarthropods using emergence traps, peat sorting, and pitfall traps in two Ontario fens, differing in water table, nutrient level, and vegetation. Altogether I found 218 arthropod morphospecies, with each site having a similar richness of emergent arthropods, however patterns of community composition differed between the two sites. The Carex (sedge) dominated site had twice as many emergent individuals, and total abundances declined dramatically over the growing season, while the Sphagnum (moss) dominated site had a much less variable arthropod community. Seasonal changes in soil moisture and daily maximum temperature were important correlates of arthropod abundance. As Canadian peatlands face increasing climate warming, this study provides baseline information on the resident macroarthropod communities in different peatland types.
To avoid overexploitation of waterfowl populations, harvest strategies must incorporate accurate information on connectivity between breeding and harvest areas, which necessitates efficient assignment of origin for harvested individuals. Current estimates of breeding metrics rely on wing samples and band returns which are assumed to be representative of a continuous breeding population, but this is unlikely accurate for some species. Stable hydrogen isotopes (δ2H) are naturally occurring intrinsic markers that can be used to infer geographic origin on a continental scale without the need for initial marking. My objective is to utilize ratios of stable isotopes within feathers to determine probabilistic origin of harvested waterfowl in the Great Lakes region and evaluate current knowledge on connectivity. Feathers were collected from wings submitted to the species composition survey. Probabilistic origin was determined using likelihood-based assignment algorithms. Results from this integrative approach will be useful to evaluate and improve adaptive harvest management.