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Full-Text Articles in Life Sciences
Lidar Remote Sensing Variables Predict Breeding Habitat Of A Neotropical Migrant Bird, Scott J. Goetz, Daniel Steinberg, Matthew G. G. Betts, Richard T. Holmes
Lidar Remote Sensing Variables Predict Breeding Habitat Of A Neotropical Migrant Bird, Scott J. Goetz, Daniel Steinberg, Matthew G. G. Betts, Richard T. Holmes
Dartmouth Scholarship
A topic of recurring interest in ecological research is the degree to which vegetation structure influences the distribution and abundance of species. Here we test the applicability of remote sensing, particularly novel use of waveform lidar measurements, for quantifying the habitat heterogeneity of a contiguous northern hardwoods forest in the northeastern United States. We apply these results to predict the breeding habitat quality, an indicator of reproductive output of a well-studied Neotropical migrant songbird, the Black-throated Blue Warbler (Dendroica caerulescens). We found that using canopy vertical structure metrics provided unique information for models of habitat quality and spatial patterns of …
Habitat-Mediated Foraging Limitations Drive Survival Bottlenecks For Juvenile Salmon, Brian P. Kennedy, Keith H. Nislow, Carol L. Folt
Habitat-Mediated Foraging Limitations Drive Survival Bottlenecks For Juvenile Salmon, Brian P. Kennedy, Keith H. Nislow, Carol L. Folt
Dartmouth Scholarship
Realistic population models and effective conservation strategies require a thorough understanding of mechanisms driving stage-specific mortality. Mortality bottlenecks for many species occur in the juvenile stage and are thought to result from limitation on food or foraging habitat during a "critical period" for growth and survival. Without a way to account for maternal effects or to measure integrated consumption rates in the field, it has been virtually impossible to test these relationships directly. Hence uncertainties about mechanisms underlying such bottlenecks remain. In this study we randomize maternal effects across sites and apply a new method for measuring consumption integrated over …
Linking Direct And Indirect Data On Dispersal: Isolation By Slope In A Headwater Stream Salamander, Winsor H. Lowe, Gene E. Likens, Mark A. Mcpeek, Don C. Buso
Linking Direct And Indirect Data On Dispersal: Isolation By Slope In A Headwater Stream Salamander, Winsor H. Lowe, Gene E. Likens, Mark A. Mcpeek, Don C. Buso
Dartmouth Scholarship
There is growing recognition of the need to incorporate information on movement behavior in landscape-scale studies of dispersal. One way to do this is by using indirect indices of dispersal (e.g., genetic differentiation) to test predictions derived from direct data on movement behavior. Mark–recapture studies documented upstream-biased movement in the salamander Gyrinophilus porphyriticus (Plethodontidae). Based on this information, we hypothesized that gene flow in G. porphyriticus is affected by the slope of the stream. Specifically, because the energy required for upstream dispersal is positively related to slope, we predicted gene flow to be negatively related to change in elevation between …
Predators And Life Histories Shape Lestes Damselfly Assemblages Along A Freshwater Habitat Gradient, Robby Stoks, Mark A. Mcpeek
Predators And Life Histories Shape Lestes Damselfly Assemblages Along A Freshwater Habitat Gradient, Robby Stoks, Mark A. Mcpeek
Dartmouth Scholarship
Survey data from New England showed that assemblages of Lestes damselflies are organized along the entire gradient of pond permanence and predator presence. One assemblage occupies vernal ponds lacking large dragonfly predators and fish; four are largely confined to temporary ponds that typically contain dragonfly predators; one dominates fishless permanent ponds and lakes where dragonflies are the top predators; and one dominates permanent ponds and lakes where fish are the top predators. We determined the role of life history and predation in maintaining this striking pattern by conducting a series of transplant experiments in the field and a laboratory experiment …
Linking Dispersal To Local Population Dynamics: A Case Study Using A Headwater Salamander System, Winsor H. Lowe
Linking Dispersal To Local Population Dynamics: A Case Study Using A Headwater Salamander System, Winsor H. Lowe
Dartmouth Scholarship
Dispersal can strongly influence local population dynamics and may be critical to species persistence in fragmented landscapes. Theory predicts that dispersal by resident stream organisms is necessary to offset the loss of individuals to downstream drift. However, there is a lack of empirical data linking dispersal and drift to local population dynamics in streams, leading to uncertainty regarding the general demographic significance of these processes and the power of drift to explain observed dispersal patterns. I assessed the contribution of dispersal along a first-order stream to population dynamics of the headwater salamander Gyrinophilus porphyriticus (Plethodontidae). I conducted mark–recapture surveys of …
Predators And Life Histories Shape Lestes Damselfly Assemblages Along A Freshwater Habitat Gradient, Robby Stoks, Mark A. Mcpeek
Predators And Life Histories Shape Lestes Damselfly Assemblages Along A Freshwater Habitat Gradient, Robby Stoks, Mark A. Mcpeek
Dartmouth Scholarship
Survey data from New England showed that assemblages of Lestes dam- selflies are organized along the entire gradient of pond permanence and predator presence. One assemblage occupies vernal ponds lacking large dragonfly predators and fish; four are largely confined to temporary ponds that typically contain dragonfly predators; one dom- inates fishless permanent ponds and lakes where dragonflies are the top predators; and one dominates permanent ponds and lakes where fish are the top predators. We determined the role of life history and predation in maintaining this striking pattern by conducting a series of transplant experiments in the field and a …
Consequences Of Dominance-Mediated Habitat Segregation In American Redstarts During The Nonbreeding Season, Peter P. Marra, Richard T. Holmes
Consequences Of Dominance-Mediated Habitat Segregation In American Redstarts During The Nonbreeding Season, Peter P. Marra, Richard T. Holmes
Dartmouth Scholarship
Several species of migratory songbirds exhibit a distinct form of habitat segregation while on their Neotropical wintering grounds in which males and females occupy different habitat types. In the American Redstart (Setophaga ruticilla), that sexual habitat segregation is a result of behavioral dominance of older males. In that study, we examined whether such dominance behavior and the resulting differential habitat segregation has consequences for the condition or survival of excluded individuals. We quantified the physical condition and survival of redstarts (both males and females) occupying two habitat types that differed in the proportion of males and females present …
Site-Dependent Regulation Of Population Size: A New Synthesis, Nicholas L. Rodenhouse, Thomas W. Sherry, Richard T. Holmes
Site-Dependent Regulation Of Population Size: A New Synthesis, Nicholas L. Rodenhouse, Thomas W. Sherry, Richard T. Holmes
Dartmouth Scholarship
The nature and extent of population regulation remains a principal unanswered question for many types of organisms, despite extensive research. In this paper, we provide a new synthesis of theoretical and empirical evidence that elucidates and extends a mechanism of population regulation for species whose individuals preemptively use sites that differ in suitability. The sites may be territories, refuges from predation, oviposition sites, etc. The mechanism, which we call site dependence, is not an alternative to density dependence; rather, site dependence is one of several mechanisms that potentially generate the negative feedback required for regulation. Site dependence has two major …