Concerns associated with growing white-tailed deer (Odocoileus virginianus) numbers in Ottawa, Ontario have motivated several studies related to the distribution and ecology of deer in the Ottawa-Carleton region. This project infers deer-population trends from deer-vehicle collisions in Ottawa, Ontario, and considers the influence of traffic volume on estimates of population dynamics from deer-vehicle collision data. Traffic volume and collision data for various road segments across suburban Ottawa were analyzed to answer questions related to the characteristics and spatial distribution of deer collisions and traffic volume in the city. Deer-vehicle collisions are increasing at a faster rate than traffic volume, suggesting that the deer population is increasing. The distribution of collisions supports the boundaries previously suggested for the location of one deerherd summer range, but not the other. Deer-collision numbers east and west of the Rideau River, a likely barrier to deer movement, were very similar, even though research and concern related to deer numbers has been concentrated west of the Rideau. More collisions occurred on 400-series highways than on other roads, suggesting that highways are a higher risk for deer collisions than other roads. The number of deer-vehicle collisions is much higher on recently constructed 400-series highways than on older 400-series highways, indicating that new highways represent high-risk areas for collisions. This research suggests that deer-vehicle collisions could be a very useful data source for inferring deer population dynamics of suburban deer, but it is imperative that significant factors affecting the number and distribution of collisions, such as category of road and traffic volume, are considered during any analyses.

Vehicular traffic can be a major source of mortality for some species. Highly uagile organisms may be at a disadvantage in landscapes with roads because they are more likely to encounter roads and incur traffic mortality. To test this prediction, we assessed the population abundance of two anuran species of differing vagility, the leopard frog (Rana pipiens more vaglie) and the green frog (Rana clamitans, less vagile), at30 breeding ponds. Traffic density, an index of the amount of potential traffic mortality, was measured in concentric circles radiating from the ponds out to 5 km. We conducted multiple linear regressions relating population abundance to traffic density, pond variables, and landscape habitat variables and found that leopard frog population density was negatively affected by traffic density within a radius of 1.5km. There was no evidence that the presence of vehicular traffic affected green frog populations, these results suggest that traffic mortality can cause population declines and that more vagile species may be more vulnerable to road mortality than less vagile species.

Concern is growing over the fragmentation of habitats by roads and other transportation infrastructure. A number of measures to avoid, minimize, mitigate, or compensate for the detrimental effects of such fragmentation have been suggested. These are geared to specific scales, from culverts at the scale of a single road to plans for re-connecting habitats across entire countries or continents. They include the removal of roads, building of overpasses and underpasses at roads and railways to increase permeability for animals, restoration or creation of wildlife corridors and networks of wildlife corridors across transportation infrastructure, and the design of less fragmenting road network patterns, e.g., the bundling of traffic lines. However, it is still unknown which measures are the most effective in terms of restoring ecological processes. The investigation of their effectiveness, therefore, is an important and most urgent task because the most effective measures should be applied predominantly in order to use resources most efficiently. How can the effectiveness of such measures be evaluated (criteria and methods)? For example, possible criteria for the effectiveness of crossing structures are the reduction of road-kill frequencies, increased passage frequencies, presence of species on both sides of the road, genetic exchange across the road, recovery of lowered reproductive rates and skewed sex ratios, re-colonization success, recovery of skewed foraging intensities among foraging areas on either side of the road, and recovery of skewed predation rates. More generally, the measures should enhance landscape connectivity and restore ecological processes among habitat patches and across landscapes. During the last three years, considerable progress on measuring the effectiveness of such measures has been made in both Europe and North America. This session brought together the “Father of Road Ecology” Richard Forman with researchers from Europe (Austria, The Netherlands, etc.) and North America working at different scales and in different locations. They presented current methods and results on the success of various mitigation measures to foster cross-scale comparison and synthesis on this topic. The presentation included empirical studies, synthetic overviews, modeling studies, and conceptual studies.

Certain combinations of time trends in traffic volume and traffic-related wildlife mortality can provide strong evidence for trends in the wildlife population itself. For example, if traffic volume increases over time while traffic-related wildlife mortality decreases over time, the wildlife population itself is almost certainly decreasing. From 1995 to 1999 the traffic volume on a road at the north end of Key Largo, Florida, increased steadily from 2,500 to 3,900 annual average daily traffic (AADT). Complete daily surveys of wildlife road kill over the same period, conducted by Florida State Parks employees, revealed significant declines in the numbers of both birds and herptiles killed over the same period. We argue that the combination of increasing traffic volume with decreasing road kills indicates declines in these wildlife populations. We present a general scheme for interpretation of joint trends in traffic volume and traffic-related wildlife mortality.

Roads act as barriers to animal movement, thereby reducing the accessibility of resources on the other side of the road. Roads also increase wildlife mortality due to collisions with vehicles, and reduce the amount and quality of habitat. The purpose of this study was (1) to determine whether or not the configuration of road networks has an influence on the degree to which roads detrimentally affect wildlife populations and (2) to identify characteristics of road network configurations that make road networks less detrimental to the persistence of animal populations. To explore these questions, we used a spatially explicit individual-based stochastic-simulation model of population dynamics. A measure assumed to reduce the effects of the road network is the bundling of roads and traffic in order to keep as large areas as possible free from disturbances due to traffic. However, the suitability of this measure may be questionable because a group of several roads bundled together, or an upgraded road with more traffic on it, creates a stronger overall barrier effect that may be more detrimental to population persistence than the even distribution of roads across the landscape. Our modelling results clearly supported the bundling concept. Population persistence was generally better (and never lower) when all traffic was put on one road than when it was distributed on several roads across the landscape. If traffic cannot be combined on one road, the model results suggested it is better to bundle the roads close together than to distribute them evenly across the landscape. We also were interested in the question of whether the effect of a road network was determined by the number and size of the pieces (“patches”) that it fragments a landscape into or by the total length of roads in the landscape. We expected that the effect of a road network would be the more detrimental the more patches it creates. The results were surprising: The expectation that fragmenting the landscape into more patches would be more harmful to population persistence (while total road length is kept constant) was contradicted by the model results in the case where the degree of road avoidance by the animals was low. This implies that for animals that do not very strongly avoid roads, it is more important to preserve core habitats at a sufficient distance from roads than to keep the number of patches low. Our results are an important step towards a network theory for road ecology and towards the design of lessdetrimental road networks. Empirical studies comparing landscapes with differing road network configurations should be conducted in the future to validate the predictions and to provide a basis for developing more practical models for use in planning and designing of highway networks. Keywords: barrier effect, bundling of roads, core habitat, landscape connectivity, landscape fragmentation, population viability analysis (PVA), road avoidance, road configuration, roads, spatially explicit population model (SEPM), traffic mortality.

We investigated whether white-footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus) were capable of crossing roads with varying levels of traffic volume. We live-trapped small mammals in 24 “home” patches. We uniquely marked and translocated 197 white-footed mice and 115 eastern chipmunks to nearby forest patches. Recaptured animals were recorded as successful returns. Forty five (22.8%) of the mice and 22 (19.1%) of the chipmunks returned to their home patches within six days of their release. Traffic on roads between the capture and release sites had a significant negative effect on small mammal return rates. No small mammals returned when moved across roads with average annual daily traffic over 11,000. Roads with low traffic may be weak barriers to movement, but high traffic prevents successful crossing.

We studied the effect of traffic intensity on local abundance of anurans. We counted dead and live frogs and toads per km and estimated frog and toad local abundances using breeding chorus intensities on similar roads through similar habitats, but with different levels of traffic intensity. After correcting for effects of date, local habitat, time, and region, our analyses demonstrated that (1) the number of dead and live frogs and toads per km decreased with increasing traffic intensity; (2) the proportion of frogs and toads dead increased with increasing traffic intensity; and (3) the frog and toad density, as measured by the chorus intensity, decreased with increasing traffic intensity. Taken together, our results indicate that traffic mortality has a significant negative effect on the local density of anurans. Our results suggest that recent increases in traffic volumes worldwide are probably contributing to declines in amphibian populations, particularly in populated areas.