Colleen Cassady St. Clair

SPATIAL RESPONSES OF WOLVES TO ROADS AND TRAILS IN MOUNTAIN VALLEYS

Increasing levels of human activity in mountainous areas have high potential to inhibit animal movement across and among valleys. We examined how wolves respond to roads, trails, and other developments. We recorded the movements of two wolf packs for two winters by following their tracks in the snow and simultaneously recording positions with a hand-held global positioning system. We then used matched case-controlled logistic regression to compare habitat covariates of wolf paths (cases) to multiple paired random locations (controls). This analysis emphasized the differences within pairs of cases and controls, rather than differences in their overall distribution, making it useful to assess fine-scale habitat selection and path data. Both packs selected low elevations, shallow slopes, and southwest aspects. They selected areas within 25 m of roads, trails, and the railway line and more strongly selected low-use roads and trails compared to high-use roads and trails. One pack strongly avoided distances bet...

Plants integrate information about nutrients and neighbors.

Plant root growth is modified in the presence of within-species competition and uneven local resource distributions. Animals regularly integrate information about the location of resources and the presence of competitors, altering their foraging behavior accordingly. We studied the annual plant Abutilon theophrasti to determine whether a plant can demonstrate a similarly complex response to two conditions: presence of a competitor and heterogeneous resource distributions. Individually grown plants fully explored the pot by using a broad and uniform rooting distribution regardless of soil resource distributions. Plants with competitors and uniform soil nutrient distributions exhibited pronounced reductions in rooting breadth and spatial soil segregation among the competing individuals. In contrast, plants with competitors and heterogeneous soil nutrient distributions reduced their root growth only modestly, indicating that plants integrate information about both neighbor and resource distributions in determining their root behavior.

Riparian corridors enhance movement of a forest specialist bird in fragmented tropical forest

Riparian corridors and fencerows are hypothesized to increase the persistence of forest animals in fragmented landscapes by facilitating movement among suitable habitat patches. This function may be critically important for forest birds, which have declined dramatically in fragmented habitats. Unfortunately, direct evidence of corridor use has been difficult to collect at landscape scales and this limits support for corridors in conservation planning. Using telemetry and handheld GPS units, we examined the movement of forest birds by translocating territorial individuals of barred antshrikes (Thamnophilus doliatus; a forest specialist) and rufous-naped wrens (Campylorhynchus rufinucha; a forest generalist) 0.7–1.9 km from their territories in the highly fragmented tropical dry forest of Costa Rica. In each translocation, the directly intervening habitat comprised 1 of 3 treatments: forested riparian corridor, linear living fencerow, or open pasture. Antshrikes returned faster and with greater success in riparian corridors relative to pasture treatments. This species also traveled more directly in riparian corridor treatments, detoured to use forested routes in the other 2 treatments, and did not use fencerows even when they led directly to their home territories. By contrast, wrens were more likely to use fencerows when returning, and return time and success were equivalent among the 3 treatments. Both species crossed fewer gaps in tree cover during riparian corridor treatments than in fencerow or pasture treatments. We conclude that antshrikes, which may be representative of other forest specialists, use forested corridors for movement in this landscape and that fencerows are avoided as movement conduits.

Path Tortuosity and the Permeability of Roads and Trails to Wolf Movement

Few studies have examined the effects of human development on fine-scale movement behavior, yet understanding animal movement through increasingly human-dominated landscapes is essential for the persistence of many wild populations, especially wary species. In mountainous areas, roads and trails may be particularly deserving of study because they are concentrated in the valley bottoms where they can impede animal movement both across and between valleys. In this study, we tracked wolf (Canis lupus) movement in the snow for two winters in Jasper National Park, Alberta, Canada to examine how wolves navigate through or around human-use features. We quantified the effects of human development and topography on the tortuosity of wolf paths and then tested the permeability of roads, trails, and a railway line to wolf movement by comparing the frequency with which actual wolf paths and a null model of random paths crossed these features. Wolf path tortuosity increased near high-use trails, within areas of high-trail and road density, near predation sites, and in rugged terrain. Wolves crossed all roads, trails, and the railway line 9.7% less often than expected, but avoided crossing high-use roads more than low-use trails. Surprisingly, trails affected movement behavior of wolves equally, if not more, than roads. These results suggest that although roads and trails in this study were not absolute barriers to wolf movement, they altered wolf movements across their territories.

Winter Responses of Forest Birds to Habitat Corridors and Gaps

Forest fragmentation and habitat loss may disrupt the movement or dispersal of forest-dwelling birds. Despite much interest in the severity of these effects and ways of mitigating them, little is known about actual movement patterns in different habitat types. We studied the movement of wintering resident birds, lured by playbacks of mobbing calls, to compare the willingness of forest birds to travel various distances in continuous forest, along narrow corridors (fencerows), and across gaps in forest cover. We also quantified the willingness of Black-capped Chickadees ( Poecile atricapillus ) to cross gaps when alternative forested detour routes were available. All species were less likely to respond to the calls as distance increased to 200 m, although White-breasted Nuthatches ( Sitta carolinensis ) and Hairy Woodpeckers ( Picoides villosus ) were generally less likely to respond than chickadees and Downy Woodpeckers (P. pubescens ). Chickadees were as likely to travel in corridors as in continuous forest, but were less likely to cross gaps as the gap distance increased. The other species were less willing to travel in corridors and gaps relative to forest, and the differences among habitats also increased with distance. For chickadees, gap-crossing decisions in the presence of forested detours varied over the range of distances that we tested, and were primarily influenced by detour efficiency (the length of the shortcut relative to the available detour). Over short distances, birds used forested detours, regardless of their efficiency. As absolute distances increased, birds tended to employ larger shortcuts in the open when detour efficiency was low or initial distance in the open was high, but they limited their distance from the nearest forest edge to 25 m. Thus, chickadees were unwilling to cross gaps of > 50 m when they had forested alternatives, yet they sometimes crossed gaps as large as 200 m when no such choice existed. Our results suggest that the presence of corridors enhanced the movement of some, but not all, forest birds, and that even chickadees, which were less sensitive to gap width, preferred not to venture far from forest cover.

Focusing the metaphor: plant root foraging behaviour

Many authors assert that plants exhibit complex behaviours which are analogous to animal behaviour. However, plant ecologists rarely root these studies in a conceptual foundation as fertile as that used by animal behaviourists. Here we adapt the optimality principles that facilitated numerous advances in the study of animal foraging behaviour to create one possible framework for plant foraging behaviour. Following the traditions of animal foraging ecology, we discuss issues of search and handling in relation to plant root foraging. We also develop a basic plant-centered model that incorporates modular growth and foraging currencies relevant to plant growth. We conclude by demonstrating how this new foundation could be adapted to address five fundamental questions in plant foraging ecology.

Physiology, Behavior, and Conservation

Many animal populations are in decline as a result of human activity. Conservation practitioners are attempting to prevent further declines and loss of biodiversity as well as to facilitate recovery of endangered species, and they often rely on interdisciplinary approaches to generate conservation solutions. Two recent interfaces in conservation science involve animal behavior (i.e., conservation behavior) and physiology (i.e., conservation physiology). To date, these interfaces have been considered separate entities, but from both pragmatic and biological perspectives, there is merit in better integrating behavior and physiology to address applied conservation problems and to inform resource management. Although there are some institutional, conceptual, methodological, and communication-oriented challenges to integrating behavior and physiology to inform conservation actions, most of these barriers can be overcome. Through outlining several successful examples that integrate these disciplines, we conclude that physiology and behavior can together generate meaningful data to support animal conservation and management actions. Tangentially, applied conservation and management problems can, in turn, also help advance and reinvigorate the fundamental disciplines of animal physiology and behavior by providing advanced natural experiments that challenge traditional frameworks.

Management options to reduce boat disturbance on foraging black guillemots (Cepphus grylle) in the Bay of Fundy

Boat disturbance of foraging black guillemots (Cepphus grylle) was studied at a breeding colony in the Bay of Fundy, Canada. Using observations from a cliff top, flushing behaviour was examined in relation to boat characteristics, guillemot behaviour, and environment conditions. The distance guillemots foraged from shore and the size, speed, and approach distance of boats were important factors predicting flushing probability. Guillemots foraged further from shore at low tide presumably making them more vulnerable to disturbance then. Using these results to identify the conditions that would minimize disturbance, management recommendations on boat speed and set-back distance were developed. At this site, a set-back distance of 600 m from shore with a speed limit of 25 km/h would reduce guillemot flushing probability to 10% most of the time. Although specific management options are proposed for this particular colony, the analytical approach used to identify an appropriate set back distance and some of the specific results are relevant to other locations and colonial waterbird species.

Unfit mothers? Maternal infanticide in royal penguins

Abstract Crested penguins (genus Eudyptes ) have a remarkable brood reduction system in which the first of two eggs laid is much smaller than the second and frequently disappears from the nest. The causes of this mortality are uncertain. In royal penguins, E. schlegeli , 70 of 84 pairs lost their first egg during the 4-day interval before the second was laid, and in 15 of 22 observed losses, mothers actively ejected their own eggs from the nest. Most first-egg losses (57%) occurred within a day prior to the appearance of the second egg. Parental ejection in royal penguins was not associated with high rates of extra-pair parentage: DNA fingerprinting of 13 two-chick families detected only one individual that was unrelated to its putative father. A manipulation experiment, intended to assess the viability and insurance value of first eggs, yielded equivocal results. The hatching success of first eggs, which were temporarily removed and then substituted for second eggs, was only half that of second eggs that were not removed (48% versus 93%, N =89), but apparent viability differences due to egg type may have been confounded by delayed incubation and additional handling. None the less, the apparent reproductive value of first eggs was low; only one of 137 unmanipulated first eggs hatched. Some testable hypotheses are suggested for the evolution of ejection behaviour in Eudyptes .

Multiple mechanisms of reversed hatching asynchrony in rockhopper penguins

Brood reduction in birds is frequently associated with hatching asynchrony, wherein incubation commences before clutch completion, causing last-laid eggs to hatch after earlier eggs. In crested penguins (Eudyptes spp.), second-laid eggs typically hatch before first-laid eggs, but the mechanisms behind this reversal are unknown. Through a multifactor field experiment with rockhopper penguins (Eudyptes chrysocome Forster 1781), I examined several factors that might influence incubation length : laying order (smaller first-laid eggs vs. larger second-laid eggs) ; incubation onset (exposure to immediate vs. delayed incubation) ; intraclutch dimorphism (incubated with an equal-sized vs. larger nest mate) ; laying date ; egg mass ; and egg composition (yolk and albumen content). Three of these factors - laying order, intraclutch dimorphism and laying date-contributed significantly to variation in incubation length ; first-laid eggs produced early in the season and incubated with a larger nest mate took longest to hatch. Differences in incubation onset did not contribute to incubation length when tested independently. The albumen content of both first and second eggs increased in proportion to fresh egg mass, but egg mass had no effect on incubation length. Although Eudyptes parents can potentially adjust the degree of hatching asynchrony through variation in egg position, the effects of laying date and laying order are probably beyond facultative control. Together, these effects may contribute to the unique reversal in both hatching asynchrony and egg-size dimorphism characteristic of crested penguins.