Biology

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This is the collection for the University of Waterloo's Department of Biology.

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The importance of long-term capture-mark-recapture archives for wildlife monitoring and research: Two examples from bat populations
(University of Waterloo, 2021-05-05) Grottoli, Adam; Broders, Hugh
Long-term capture-mark-recapture (CMR) projects provide useful data to study and monitor wildlife. Specifically, CMR data can help identify how an animal interacts with its environment and how these interactions change throughout its life. In this thesis, I use data and sample archives from temperate hibernating bats captured and tagged as part of a long-term project in Newfoundland and Labrador, Canada. In Chapter 2, I use fur collected from adult female 𝑀𝑦𝑜𝑡𝑖𝑠 𝑙𝑢𝑐𝑖𝑓𝑢𝑔𝑢𝑠 captured multiple times from 2012-2017 to investigate age dependent changes in the concentration of the toxic compound, methylmercury (MeHg). Results suggest total mercury concentrations, which are highly correlated with MeHg, decrease with age in the fur of adult female bats. This pattern indicates that adult female bats can eliminate enough MeHg from their tissues to have steady or decreasing concentrations in their fur. In Chapter 3, I use forearm measurements taken by multiple observers from captured and tagged 𝑀. 𝑙𝑢𝑐𝑖𝑓𝑢𝑔𝑢𝑠 and 𝑀𝑦𝑜𝑡𝑖𝑠 𝑠𝑒𝑝𝑡𝑒𝑛𝑡𝑟𝑖𝑜𝑛𝑎𝑙𝑖𝑠 to quantify the measurement error and observer bias associated with this morphometric variable. Results suggest measurement error can add enough variation to mask relationships between forearm length and related variables. Further, observer bias can cause type I errors when comparing populations with small differences in forearm length that were measured by different observers. These two studies exemplify the use of long-term CMR projects as an invaluable tool to assess research techniques, study wildlife biology, and monitor ecological changes.
Long-term decline in bat activity using passive acoustic monitoring and an equipment correction factor in Nova Scotia, Canada
(University of Waterloo, 2020-09-28) Phinney, Lori; Broders, Hugh
Passive acoustic monitoring has grown in popularity as a technique to assess changes in activity levels of various taxa. However, there are few long-term and large-scale acoustic monitoring programs due to the current challenges associated with advancing technology, data management and analyses. The variation in the quality and quantity of acoustic data collected by different equipment setups has become challenging to avoid. There are an increasing number of equipment options that provide different or improved detection capabilities as old models wear and phase out. To assess long-term activity trends of bats between two data sets collected by different equipment in southwest Nova Scotia, Canada, I developed equipment variation correction factors. I compared the assumed proportion of successful detections as given by binomial distribution between two types of bat acoustic monitors positioned side by side. I found the proportion of successful Anabat SD1 to Song Meter SM4 detections to vary by night (n=5), height (3 m, 6 m) and species (Myotis lucifugus, Perimyotis subflavus). There was no systematic bias in the correction factors when I compared the Anabat to the corrected Song Meter detections as indicated by mean errors centered around zero. After applying the correction factors, acoustic activity of Myotis lucifugus declined by 95.50% 95% CI (96.96%, 93.59%) and Perimyotis subflavus declined by 91.37% 95% CI (92.99%, 89.49%) between 2005/2006 and 2018/2019 across southwest Nova Scotia. These trends reflect declines in winter colony counts and summer capture rates across eastern North America attributable to the disease White Nose Syndrome (WNS). My results demonstrate that direct comparisons of data sets collected by different acoustic equipment cannot be made and that equipment variation needs to be accounted for in order to assess long-term activity patterns. Exploring techniques to account for equipment variation and their efficacy will increase our ability to use acoustic data to track long-term population trends and manage wildlife populations. Managers can continue to use acoustics to assess population trends in areas with no known hibernation sites, for species difficult to study in hibernacula and to identify areas that may be significant for WNS recovery. In Nova Scotia, Kejimkujik National Park and National Historic Site may serve as an important area for WNS recovery. Periodic monitoring should continue to document population trends and this long-term data set may be used to track summer population changes.
The role of social preferences in the organization of a gregarious mammal colony
(University of Waterloo, 2022-12-02) Sunga, Julia; Broders, Hugh
Social preferences are often demonstrated to exist in “intelligent”, long-lived species, such as cetaceans and primates, where individuals have the opportunity to form relationships with conspecifics through repeated interactions. The long lifespan of bats combined with the regular roost switching behaviour of females in some temperate species, presents opportunity for females to build and act on social relationships. However, regular roost switching also poses a challenge for teasing apart the individual influences of social and habitat preferences. To gather evidence for the influence of social preference, I tested predictions of a hypothesis that bats select daily roosts based on social preferences. Using a system of little brown myotis (Myotis lucifugus) individually marked with passive integrated transponder tags and passively monitored roost boxes in Newfoundland, Canada, I quantified the number of days bats spent in each roost, and the number of days spent sharing a roost with other marked bats to characterize patterns in co-roosting association. I found that patterns of roost use do not entirely explain the frequency of roosting association between pairs of female bats. Further, association patterns showed predictable changes following estimated parturition dates, estimated based on nighttime roost revisit behaviour, as adult females are expected to experience changes in selective pressures and mobility with the onset of the lactation period. I also found that patterns of roosting association between individual bats often persisted for more than 5 years and could even persist for up to 10 years following the first observed interaction. Using this same dataset, I also address the effect of missing information on estimates of social network structure, providing a deeper understanding of the ability of these results to inform on the structure of the underlying population. Overall, my findings add to evidence that supports that bats act on social preferences, and thus make a case for social complexity in bat groups. These findings further suggest that, perhaps due to their similarly long life spans, bats may be more similar to their large-bodied, “intelligent”, mammal counterparts than previously expected.
Roost Selection and Mass Variation Patterns of Temperate Bats in Eastern Canada
(University of Waterloo, 2021-08-23) Balzer, Evan; Broders, Hugh
Animals are expected to adjust their resource selection and behavioural patterns to improve fitness outcomes, such as fecundity or offspring survival. For long-lived hibernators, decisions made in each annual cycle may reflect considerations both for concurrent survival and reproduction, but also the pressure to maximize overwinter survival and future reproductive success. I examined how these elements manifest themselves in the roost selection and body mass variation patterns of temperate bats. First, I tested whether roost selection by little brown bats (Myotis lucifugus) on Prince Edward Island could be explained by landscape characteristics. Given a sample of roosts identified through radio telemetry and community reports and a randomly selected sample of comparison structures, I determined that a combination of proximity to forest and open wetland best explained roost selection. Second, I characterized the summer and fall mass variation patterns of both little brown myotis and northern myotis (M. septentrionalis) from a historic dataset. In summer, the estimated date of parturition was strongly associated with spring foraging conditions (low wind, low precipitation, warm temperatures), and mass gain associated with female reproduction conferred considerable differentiation between the mass variation patterns of females and males. In fall, differences were most apparent among species, although adults exhibited a greater capacity for rapid mass gain than juveniles. These results demonstrate how reproductive constraints and interannual survival have important influences on the behaviour of temperate bats. Roost selection appears to reflect the optimization of time and energy budgets, and the proportion of maternity roosts within the sample supports the contention that the effect of these constraints on roost selection may be more acute in reproductive females. Similarly, the relationship between foraging conditions and the timing of parturition provides further evidence that females facilitate early parturition through a combination of roost selection and capitalization on favourable foraging conditions. In fall however, the shared requirement of prehibernation mass gain among species, ages, and sexes yielded lower differentiation in mass variation than summer. Collectively, these outcomes provide evidence for the nuanced influence of life history characteristics on temperate bat behaviour. The disparate summer characteristics among sexes identified in my work suggest that management should provide nuanced supports for these endangered species, including the identification and preservation of important anthropogenic maternity roosts. Future work should seek to clarify the role of physical characteristics on roost structure selection and quantify the fitness benefits of patterns identified in this study, such as the rate of prehibernation mass gain.
Stable Isotope Ecology of Tropical Bats
(University of Waterloo, 2019-08-12) Oelbaum, Phillip; Broders, Hugh
Stable isotopes have been used to characterize differences in animal diet and behaviour since experimental studies by DeNiro and Epstein (1979; 1981). Examining isotopic ratios enables researchers to track how animals interact with their environment as these ratios are derived from intake of nutrients and are fractionated into tissue at a calculable factor; in short, ‘you are what you eat’ (Tykot 2004). Studying bats, I use carbon (δ13C) and nitrogen (δ15N) stable isotopes to: (1) characterize community structure of a diverse fauna in Belize, (2) examine dietary differences between populations in a fragmented forest in Brazil, and (3) tested multiple tissues from the same individual to discern seasonal difference in diet in species from both the Neotropics and Paleotropics. In Belize, I found significant amounts of niche overlap between species which I predicted would belong to different guilds, and several cases of overlap which would suggest that species may compete for resources. In Brazil, I found that habitat composition (i.e., vegetation density) was more important than landscape metrics (sic fragment area, fragment nearest neighbour distance, etc.) in predicting the diets of frugivorous bats. I also found that multi-tissue stable isotope analysis is valuable in determining both individual variation in diet throughout the year and tracking seasonal changes as a result of resource availability or local-scale migration. Stable isotope analysis is a valuable tool in understanding the dietary ecology of animals.
The evolutionary and ecological factors that shape ectoparasite populations and communities at multiple scales
(University of Waterloo, 2024-11-12) Sauk, Alexandra; Broders, Hugh
Although parasites are one of the most prolific and diverse consumer groups on the planet, they are often excluded from biodiversity surveys as they are difficult to detect and identify. This deficit limits our understanding of host-parasite relationships and parasite diversity. The vast diversity of host-parasite relationships means that many ecological and evolutionary forces may be at play, shaping the evolution of host and parasite in different ways and varying between species pairs. Bats and their ectoparasites provide a unique system to study the factors influencing parasite populations and communities. The different ecological niches and social behaviours of bats provide variation in the ectoparasites they encounter, and the selective forces experienced by the ectoparasites. I hypothesised that certain attributes of ectoparasite infections (e.g., ectoparasite diversity and infection level) are influenced by the life history traits of both host and ectoparasite and be the environmental restrictions of individual ectoparasite species. Using a collection of ectoparasites passively collected from bats throughout Atlantic Canada between 1999 and 2017, I quantified the ectoparasite communities of two bat species, Myotis lucifugus and M. septentrionalis, and used model-based inferences to assess the differences in infection of their two most common ectoparasites, the mite Spinturnix americanus and the flea Myodopsylla insignis. I found that both bat species had similar ectoparasite communities while S. americanus and M. insignis showed opposing trends in presence and abundance between the two bat species, in keeping with their different life history strategies. I also used a subset of this collection to compare how life history traits and host-parasite dynamics influence the genetic structure and biogeography of co-infecting ectoparasites. I found limited genetic structure with M. insignis exhibiting some isolation by distance between Labrador and Nova Scotia and S. americanus exhibiting regional differentiation between the island of Newfoundland and the mainland. I also provide a synthesis of the currently described bat ectoparasites in North America and an analysis of how host characteristics and environmental factors influence ectoparasite richness and geographic distribution. I found that estimated ectoparasite richness varies widely between host species but is influenced by sampling effort. Bat ectoparasite diversity appears consistent with the predictions of the latitudinal diversity hypothesis with a 3.4% decrease in species richness for every degree increase in latitude. Overall, my findings add to the evidence that ectoparasite populations and communities are shaped by life history traits of the host and ectoparasite. I suggest multidisciplinary collaborations between bat biologists, parasitologists, and taxonomists are necessary to collect ectoparasites and catalogue bat-ectoparasite associations to better understand the ecological and evolutionary forces that shape these communities and to better be able to conserve them in the face of ongoing threats from climate change and landscape changes.

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Browsing Biology by Author "Broders, Hugh"