Graham J. Forbes

Inadvertent social information in breeding site selection of natal dispersing birds

Several species use the number of young produced as public information (PI) to assess breeding site quality. PI is inaccessible for synchronously breeding birds because nests are empty by the time the young can collect this information. We investigate if location cues are the next best source of inadvertent social information (ISI) used by young prospectors during breeding site choice. We experimentally deployed ISI as decoys and song playbacks of breeding males in suitable and sub-optimal habitats during pre- and post-breeding periods, and monitored territory establishment during the subsequent breeding season for a social, bobolink (Dolichonyx oryzivorus), and a more solitary species, Nelsons sharp-tailed sparrow (Ammodramus nelsoni). The sparrows did not respond to treatments, but bobolinks responded strongly to post-breeding location cues, irrespective of habitat quality. The following year, 17/20 sub-optimal plots to which bobolink males were recruited were defended for at least two weeks, indicating that song heard the previous year could exert a ‘carry-over attraction’ effect on conspecifics the following year. Sixteen recruited males were natal dispersers, as expected when animals have little opportunity to directly sample their natal habitat quality. We suggest that differences in breeding synchronicity may induce an equivalent clinal distribution of ISI use.

The association of small mammals with coarse woody debris at log and stand scales

Coarse woody debris is an important structural element in forests. We empirically investigated the relationships between small mammals and coarse woody debris decay stage at two different scales: individual logs and forest stands. There were no significant relationships between small mammals and individual logs of different decay classes. We investigated the stand scale using areas with contrasting management intensities (a reference area and a more intensively managed area). No significant relationships were found between small mammal abundance (any species) and either mean decay class of logs in a stand, or overall abundance of logs. There was evidence of a landscape context effect. Red-backed voles, the most abundant microtine in the region, were significantly related to the abundance of the most decayed logs. This relationship was only significant on the intensively managed landscape, where highly decayed logs were rare.

Independent Effects Of Fragmentation On Forest Songbirds: An Organism-Based Approach

The degree to which spatial patterns influence the dynamics and distribution of populations is a central question in ecology. This question is even more pressing in the context of rapid habitat loss and fragmentation, which threaten global biodiversity. However, the relative influence of habitat loss and landscape fragmentation, the spatial patterning of remaining habitat, remains unclear. If landscape pattern affects population size, managers may be able to design landscapes that mitigate habitat loss. We present the results of a mensurative experiment designed to test four habitat loss vs. fragmentation hypotheses. Unlike previous studies, we measured landscape structure using quantitative, spatially explicit habitat distribution models previously developed for two species: Blackburnian Warbler (Dendroica fusca) and Ovenbird (Seiurus aurocapilla). We used a stratified sampling design that reduced the confounding of habitat amount and fragmentation variables. Occurrence and reoccurrence of both species were strongly influenced by characteristics at scales greater than the individual territory, indicating little support for the random-sample hypothesis. However, the type and spatial extent of landscape influence differed. Both occurrence and reoccurrence of Blackburnian Warblers were influenced by the amount of poor-quality matrix at 300- and 2000-m spatial extents. The occurrence and reoccurrence of Ovenbirds depended on a landscape pattern variable, patch size, but only in cases when patches were isolated. These results support the hypothesis that landscape pattern is important for some species only when the amount of suitable habitat is low. Although theoretical models have predicted such an interaction between landscape fragmentation and composition, to our knowledge this is the first study to report empirical evidence of such nonlinear fragmentation effects. Defining landscapes quantitatively from an organism-based perspective may increase power to detect fragmentation effects, particularly in forest mosaics where boundaries between patches and matrix are ambiguous. Our results indicate that manipulating landscape pattern may reduce negative impacts of habitat loss for Ovenbird, but not Blackburnian Warbler. We emphasize that most variance in the occurrence of both species was explained by local scale or landscape composition variables rather than variables reflecting landscape pattern.

Predation and survival of white-tailed deer fawns in northcentral New Brunswick

Identification of mortality sources of white-tailed deer (Odocoileus virginianus), particularly predation and survival rates, is important for effective management. We captured, radiocollared, and monitored 78 white-tailed deer fawns in northcentral New Brunswick to determine survival and cause-specific mortality from February 1994 through May 1997. Of 50 fawns captured as neonates, 22 died by 30 November 1994-96. Predation by coyotes (Canis latrans; n = 9), black bears (Ursus americanus; n = 5), domestic dogs (Canis familiaris; n = 3), and bobeats (Felis rufus; n = 2) was the largest cause of fawn mortality during summer and autumn, Coyotes were the primary cause of mortality of fawns >7 months old (11 of 15). Fawn survival was lowest during summer (0.47). increased during autumn (0.86) and early winter (0.95), and then declined during late winter (0.76) and spring (0.81). Our results support the hypothesis that coyotes have replaced gray wolves (Canis lupus) in northeastern North America, with survival and mortality rates being comparable between New Brunswick and other areas where wolves and coyotes are sympatric.

INTERSPECIFIC AND INTERSEXUAL VARIATION IN ROOST-SITE SELECTION OF NORTHERN LONG-EARED AND LITTLE BROWN BATS IN THE GREATER FUNDY NATIONAL PARK ECOSYSTEM

Abstract Although only 2 bat species are common in the Greater Fundy National Park Ecosystem of New Brunswick, Canada, 4 distinct groups occur in terms of roost-site selection due to sexual segregation. We found that female northern long-eared bats (Myotis septentrionalis) roosted alone or as part of maternity colonies in mature, shade-tolerant deciduous stands. A roost site was 24 times more likely to be in a shade-tolerant deciduous tree than a coniferous tree, and trees in the mid-decay classes were 5.2 times more likely to be used than live or recently dead trees. Male northern long-eared bats roosted alone in coniferous stands or conifer-dominated mixedwood stands, and they selected roost trees that were in the mid-decay stages. Trees in mid-decay stages were selected more than twice as often as trees at the early or late stages of decay. For every 10% increase in the proportion of coniferous trees in the plot, the chances of a male northern long-eared bat roosting in the plot increased 1.5 times. Female little brown bats (M. lucifugus) in our study area were transients. Male little brown bats primarily roosted alone in coniferous stands, or conifer-dominated mixedwood stands. Their selection of roost sites was highly dependent on the number of snags in the vicinity. For every increase of 5 snags in a 0.1-ha plot, the odds of use for male little brown bats on that site increased by 2.5 times. The long-term availability of roost sites for males of both species in our study area may be linked to spruce budworm (Choristoneura fumiferana) epizootics, which is the major mortality factor for coniferous species in the region. Female northern long-eared bat roosts probably are more consistantly available because suitable sites are created by continuously occurring, individual-tree stressors in mature shade-tolerant forests.

Range Extent and Stand Selection for Roosting and Foraging in Forest-Dwelling Northern Long-Eared Bats and Little Brown Bats in the Greater Fundy Ecosystem, New Brunswick

Abstract To understand bat biology and appreciate their dependence on and role within forested ecosystems, the biological resolution at which studies are directed must elucidate species and gender patterns. We studied species- and gender-specific aspects of summer range extent and stand selection in northern long-eared bats (Myotis septentrionalis) and little brown bats (M. lucifugus) in the Greater Fundy Ecosystem, New Brunswick, Canada, using trapping, radiotelemetry, and ultrasonic monitoring. Our results suggested that this 2-species system is comprised of 4 ecologically distinct groups with respect to site selection and range extent for roosting and foraging. All bats exhibited an affinity to specific roosting areas. Myotis septentrionalis roosted and foraged in the forest interior. The roosting and foraging areas for females were 6.1 times and 3.4 times larger, respectively, than for males. Both genders foraged in site types in proportion to their availability. Myotis lucifugus females roosted in buildings outside the core study area, and those captured in the forested landscape were transients. Compared to male and female M. septentrionalis, male M. lucifugus had intermediate-sized roosting areas but the largest foraging areas. Water sites were selected during foraging more than expected. Bat foraging activity, measured acoustically at 8 site types, was greatest at lakes and least above the forest canopy. Male M. lucifugus activity levels were positively associated with temperature and the amount of mature coniferous forest and water within 1 km of the sampling site, and they were negatively associated with the amount of mature deciduous forest within 1 km of the site. Our results suggested that understanding gender effects is crucial for accurate characterization of forest bat habitats. Studies of bats that combine data for genders, species, or guilds may produce spurious results and may be of minimal value for, or actually hinder, bat conservation and management programs.

Migration behavior of white-tailed deer under varying winter climate regimes in New Brunswick

White-tailed deer (Odocoileus virginianus) exhibit a variety of migration strategies across northern portions of their range. Factors reported as being responsible for migration initiation have shown no consistent pattern. We monitored 186 radiocollared white-tailed deer from 1994 to 1998 in 2 areas of New Brunswick: a southern area with moderate and variable winter climate and a northern area with consistently severe winter climate. We determined that deer in the south contained a large proportion of conditional migrators (individuals that may or may not migrate to winter range in a given year, and may or may not remain until spring), whereas deer in the north consisted almost entirely of obligate migrators (those that annually migrate to winter range for the duration of winter). Occurrence of conditional migration appeared to be a function of climate variability, although distribution of the behavior among individual deer was influenced by migration distance. Initiation of autumn migration in the south was related to snow depth for most deer and represented a response to the proximate cue of the onset of limiting conditions. Autumn migration in the north appeared to be a response to seasonal cues, and the direct influence of snow depth was reduced. Initiation of spring migration in the 2 study areas showed a similar pattern. Migration distance may represent a factor influencing distribution of migrational cues among individual deer within a population. The effect of winter climate variability on deer migration behavior may account for the disparity in behavior reported in the literature. The differences in migration behavior have implications for deer management surveys in northern areas where deer yarding occurs. Managers have assumed that deer observed during winter surveys were on winter range, hut this may not be a reasonable assumption in areas with variable winter climates.

A world review of fungi, yeasts, and slime molds in caves

literature on cave fungi (127 species in 59 genera) but did not include all relevant papers available at that time, and many articles have since been published. Landolt et al. (1992) summarized the few records of slime molds found in caves, but otherwise there has been no comprehensive review of the microf lora in cave habitats. Here we organize data from 225 studies dealing with fungi, yeasts, and slime molds occurring in caves, with 130 of these allowing some exploration of broader patterns of occurrence in relation to the ecology of the cave habitat. Although studies published before 1965 do provide useful records of occurrence, unfortunately many do not report their methods in suff icient detail to allow comparisons with later work. We also identify gaps in information, but most importantly, we note the need for adequately applied and consistently reported methodologies. Our hope is that the review of cave fungi presented here will prove timely and useful to both speleologists and WNS researchers.

Landscape context and small-mammal abundance in a managed forest

We assessed whether small-mammal abundance was related to landscape context, when context was considered independently of within-stand vegetation and at different spatial extents. The study took place in an industrial forest in northwestern New Brunswick. Within-stand vegetation models explained 9‐32% of the deviance in the abundance of individuals from the four most abundant species: red-backed voles; deer mice; short-tailed shrews; and woodland jumping mice. Landscape context was related to the distributions of two species: red-backed voles were less abundant within contexts of softwood plantations; and jumping mouse abundance was directly related to the amount of softwood forest. Variables measured at the largest radii of landscape context (500 m) were never significantly associated with the abundance of small mammals. Most species appeared robust to forest management with the exception of the negative relationship between redbacked voles and softwood plantations. # 2001 Elsevier Science B.V. All rights reserved.

Survival and cause-specific mortality rates of adult white-tailed deer in New Brunswick

Survival and cause-specific mortality rates between yarded and nonyarded white-tailed deer populations have not beer previously studied with the use of radiotelemetry, We captured, radiocollared, and monitored the survival of 103 adult male and female white-tailed deer (Odocoileus virginianus) in northern and southern New Brunswick from February 1994 through May 1997. Annual survival rates for adult does in northern New Brunswick were higher than those for females in the south but were not different for adult males between the 2 study areas. Six of 37 adult female mortalities in the northern, yarded population died as a result of coyote (Canis latrans) predation (0.098); doe harvest was illegal in this portion of the province, However, in the southern population, where a limited number of antlerless permits were issued but deer did not concentrate in traditional deeryards, 9 of 21 adult female mortalities were from hunting-related causes (0.114). Mortality rates for adult females as a result of predation did not differ between the 2 study areas (0.098 for north, 0.058 for south), and mortality rates of northern females (0.151) did not differ from hunting-related mortality rates for does in the south (0.128). A majority of adult males in northern New Brunswick died as a result of predation and hunting-related causes, while most (5 of 10) mortality in the southern study area resulted from legal harvest. There were no differences in adult male mortality rates among seasons or between study areas (P > 0.05), Annual survival of adult white-tailed deer in New Brunswick, where deer exist on the northern edge of their North American distribution, appeared dependent on either legal harvest rates in those populations that were exploited, or on coyote predation. Our results did not support the hypothesis that yarded white-tailed deer have higher winter survival rates than nonyarded populations.