Angela K. Fuller

INFLUENCE OF PARTIAL TIMBER HARVESTING ON AMERICAN MARTENS IN NORTH-CENTRAL MAINE

Abstract We investigated habitat selection and home-range characteristics of American martens (Martes americana) that occupied home ranges with partially harvested stands characterized by basal area of trees <18 m2/ha and canopy closure <30%. During the leaf-on season (1 May–31 Oct), martens selected second-growth (80–140-years-old, >9-m tree height) forest stands (deciduous, coniferous, and mixed coniferous-deciduous) and mixed stands that were partially harvested (x̄ = 13 m2/ha residual basal area, >9-m tree height), and they selected against forests regenerating after clearcutting (≤6-m tree height, cuts ≤24-years-old). Marten home ranges included a greater proportion of partially harvested stands during the leaf-on season (maximum = 73%) than during leaf-off (1 Nov–30 Apr; maximum = 34%). Higher use of partially harvested stands during the leaf-on season coincided with greater canopy closure, higher use of small mammals, and greater relative densities of small mammals. During the leaf-off season, martens exhibited reduced relative selection for partially harvested and regenerating stands and increased selection for second-growth forest types. Partially harvested and regenerating clearcut stands had canopy closure <30% and basal area of trees >9-m tall of <13 m2/ha; both were below published thresholds required by martens. Coincidentally, home-range areas of martens increased during the leaf-off season to include a greater proportion of second-growth forest and less partially harvested forest. Further, martens with partial harvesting in their home ranges used areas almost twice as large during the leaf-off season as martens with no partial harvesting. Snowshoe hares (Lepus americanus) were prevalent prey for martens during the leaf-off season, and partially harvested stands had the lowest density of hares among all forest overstory types. Our findings suggest that the combination of insufficient basal area and overhead canopy closure, subnivean behavior of small mammals, increased reliance on hares, and reduced density of snowshoe hares relative to second-growth forest types reduced habitat quality in partially harvested stands during the leaf-off season. We suggest land managers retain basal areas >18 m2/ha and canopy closure >30% during winter to maximize use by martens in stands where partial harvesting is practiced.

Winter Habitat Selection by Canada Lynx in Maine: Prey Abundance or Accessibility?

Abstract We related winter habitat selection by Canada lynx (Lynx canadensis), relative abundance of snowshoe hares (Lepus americanus), and understory stem densities to evaluate whether lynx select stands with the greatest snowshoe hare densities or the greatest prey accessibility. Lynx (3 F, 3 M) selected tall (4.4–7.3 m) regenerating clear-cuts (11–26 yr postharvest) and established partially harvested stands (11–21 yr postharvest) and selected against short (3.4–4.3 m) regenerating clear-cuts, recent partially harvested stands (1–10 yr), mature second-growth stands (>40 yr), and roads and their edges (30 m on either side of roads). Lynx selected stands that provided intermediate to high hare density and intermediate cover for hares (i.e., prey access) but exhibited lower relative preference for stand types with highest hare densities where coniferous saplings exceeded 14,000 stems/ha.

Looking beyond research in doctoral education

Doctoral education in the natural sciences has traditionally focused on training students as researchers. However, this is no longer sufficient to provide students with the range of skills needed to succeed in academic and non-academic employment. Based on a review of national studies and current literature, we recommend a shift from the current model, with its focus on dissertation research, to a broader conception of doctoral education that includes training and mentoring that will be relevant to future careers. We also highlight some of the national initiatives that have made progress in these areas. Doctoral education programs cannot remain static if they are to continue to create marketable graduates. Instead, partnerships should be formed with hiring institutions, so that doctoral programs can evolve in parallel with the dynamics of the job market.

Movement paths reveal scale-dependent habitat decisions by Canada lynx

Abstract We documented the relative grain at which Canada lynx (Lynx canadensis) perceive habitat heterogeneity using fractal dimension of foraging paths. We evaluated whether lynx expended greater foraging effort (i.e., greater fractal dimension of movement paths) in patches with the highest density of snowshoe hares (Lepus americanus), or in patches with intermediate densities of prey where lower stem densities and greater visibility promote increased mobility and access to prey. Lynx foraged within patches with intermediate to high hare density and intermediate cover for hares, and thus, attempted to maximize access to prey rather than exposure to habitats with highest prey density but optimal escape cover. Fractal dimension of movement paths was greater within preferred than in nonpreferred habitats and corresponded with higher foraging success in preferred habitats. Movement paths were more tortuous at broader than finer scales, suggesting that lynx were exhibiting stronger coarse-grained than fine-grained habitat preferences. Higher fractal dimension of movement paths reduced the number of transitions between patches of higher and lower foraging quality, resulting in individual movement patterns matching the scale of interpatch variation in hare abundance and accessibility within home ranges. Lynx made their strongest foraging decisions when exhibiting higher-order resource selection, so focusing conservation efforts to alter within-patch structure may be less effective than creating patch- and landscape-scale conditions that enhance foraging success. Coarse-grained resource selection by wide-ranging carnivores may reduce the importance of fine-scale conservation efforts and emphasizes the importance of focusing conservation for these coarse-grained species on factors influencing home-range quality and maintenance of viable landscapes.

Nest survival of wild turkeys Meleagris gallopavo silvestris in a mixed-use landscape: influences at nest-site and patch scales

Nest survival is a critical factor affecting avian demographics, and can be influenced by nesting chronology, fine scale nest-site selection and broad-scale landscape characteristics. We modeled the relative influences of nest age, temporal variation in nest success and habitat-related covariates at two spatial scales (nest-site and patch scale) on daily nest survival during incubation for eastern wild turkeys Meleagris gallopavo silvestris in a mixed-use landscape. Daily survival rate of turkey nests during incubation increased as percent understory cover (vegetation < 1 m tall) increased and decreased with increasing density of woody shrubs and saplings and herbaceous stems < 1 m tall (understory vegetation density) around the nest. We suggest that nest survival may be dependent on a balance of sufficient understory cover around nests to provide concealment for hens and nests, but with understory vegetation density below levels that reduce the hens ability to detect a predator or to escape after detecting a potential threat. The balance between sufficient understory cover and limited density of understory vegetation occurred where understory (< 1 m tall) cover exceeded 50% and understory vegetation density was < 25 stems/m2. Models that included variables related to the patch scale (e.g. fragmentation, edge and dominant land-cover class in a patch) did not receive strong support, demonstrating the relative importance of finer scale nest-site variables over patch-scale variables in determining survival of wild turkey nests in our highly variable mixed-use landscape.

Paradigm shifts in habitat ecology of threatened Newfoundland martens.

Abstract We evaluated multiscale habitat selection by threatened Newfoundland (Canada) martens (Martes americana atrata) across landscapes composed of a range of habitat types to test the hypothesis that martens preferred mature (61–80-yr-old) and overmature (>80 yr) conifer stands. At both the landscape and stand scales, adult (≥1 yr) resident martens (n  =  58, 92 yr-specific home ranges) selected for, or used in proportion to availability, a broad range of habitat types, including recent cuts ≤5 yr old, regenerating forest <6.5 m, precommercially thinned stands, and mature and overmature forest. Marten home ranges were not dominated by mature and overmature forest; median availability of mature and overmature forest within individual home ranges was only 30% (range  =  11–76%). Age distributions were not different among martens with high, intermediate, and low quantity of mature and overmature forest in their home range; our data do not indicate that martens inhabiting ranges with little mature and overmature forest were compromising fitness. Habitat selection by martens in Newfoundland was more generalized than has traditionally been inferred, and we suggest that inherent landscape fragmentation, in combination with absence of many predators and competitors (i.e., ecological release), caused the Newfoundland marten to evolve to use a more generalized habitat niche than many mainland populations of American martens. We recommend that landscapes suitable for marten not exceed >29% younger aged forest. Maintaining resident martens in landscapes where forest harvesting is occurring requires prescriptions that recognize the highly fragmented nature of the natural landscape, the prevalence of mature and overmature forest, younger forests, avoided land-cover types, and human access.

Citizen science data enhance spatio-temporal extent and resolution of animal population studies

Informed management and conservation decisions for animal populations often require data at sufficient geographic, temporal, and demographic resolutions for precise and unbiased estimates of parameters including population size and demographic rates. Recently developed integrated population models estimate such parameters by unifying population presence-absence and demographic data, and we demonstrate how citizen science offers a cost-efficient mechanism to collect such data. We describe the early results of iSeeMammals, a citizen science project that collects opportunistic data on the black bear population in New York State by enlisting volunteers to collect data through observations, hikes, and trail cameras. In 10 months, iSeeMammals increased the spatio-temporal extent of data collection by approximately fourfold and reduced cost by 83% compared to systematic sampling. In combination with other datasets in integrated population model frameworks, large, spatiotemporally extensive datasets from citizen science projects like iSeeMammals can help improve inferences about population-level structure and dynamics.