10 research outputs found

    Clonal structure of invasive cattail (Typhaceae

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    Abstract There is mounting evidence that the clonal dynamics of foundational plant species, including exotic invaders such as hybrid Typha x glauca, have a profound effect on wetland function. Here, we report on the clonal structure of five intensively sampled Typha stands from the Upper Midwest region where invasions have been especially disruptive. Each of these stands consisted of a large proportion of F 1 hybrids between T. latifolia and T. angustifolia, although backcrosses to both parents were also observed, and provided a means of determining relative age of invasion. We found clonal richness, measured as the proportion of ramets representing distinct genets, to vary positively with age of invasion over a range from 0.20 to 0.45, whereas Simpson's Evenness was relatively consistent among sites due to a pattern of dominance by a few large clones accompanied by many smaller clones. Ramets were significantly clumped within genets over a range of approximately 20 m, although many clones included ramets separated by as much as 60 to 90 m, suggesting some degree of clone fragmentation over time. Related genets were significantly clumped over approximately 10 m, suggesting that seedling cohorts may frequently recruit in close proximity to one another

    Moose first-passage time data

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    Data used to model moose first passage time estimates

    Wolf movement rate data

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    Wolf movement rates from GPS-collared wolves in northeastern Minnesota and Voyageurs National Park ecosystem. Data also contain other values used in movement rate analysis portion of the manuscript

    Observed nest occupancy, success and number of fledged young for osprey during 1973-2012

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    Nest occupancy, success and number of fledged young for osprey in Voyageurs National Park observed during 1973-2012 from aerial surveys. Predictors associated with each nest include descriptors for weather, ice-out dates, nest and foraging habitat, fish resources and various measures of potential intraguild predation and competition from bald eagles

    Heronry occupancy and number of nests of great blue herons observed during 1973-2012

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    Heronry occupancy and number of nests of great blue herons in Voyageurs National Park observed during 1973-2012 from aerial surveys. Predictors associated with each heronry include descriptors for nesting and foraging habitat, fish resources and various measures of potential intraguild predation and competition from bald eagles and osprey

    Data from: Moose movement rates are altered by wolf presence in two ecosystems

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    Predators directly impact prey populations through lethal encounters, but understanding non-lethal, indirect effects is also critical because foraging animals often face tradeoffs between predator avoidance and energy intake. Quantifying these indirect effects can be difficult even when it is possible to monitor individuals that regularly interact. Our goal was to understand how movement and resource selection o a predator (wolves; Canis lupus) influences the movement behavior of a prey species (moose; Alces alces). We tested whether moose avoided areas with high predicted wolf resource use in two study areas with differing prey compositions, whether avoidance patterns varied seasonally, and whether daily activity budgets of moose and wolves aligned temporally. We deployed GPS-collars on both species at two sites in northern Minnesota. We created seasonal resource-selection functions (RSF) for wolves and modeled the relationship between moose first-passage time (FPT), a method that discerns alterations in movement rates, and wolf RSF values. Larger FPT values suggest rest/foraging, whereas shorter FPT values indicate travel/fleeing. We found that the movements of moose and wolves peaked at similar times of day in both study areas. Moose FPTs were 45% lower in areas most selected for by wolves relative to those avoided. The relationship between wolf RSF and moose FPT was nonlinear and varied seasonally. Differences in FPT between low and high RSF values were greatest in winter (-82.1%) and spring (-57.6%) in northeastern Minnesota and similar for all seasons in the Voyageurs National Park ecosystem. In northeastern Minnesota, where moose comprise a larger percentage of wolf diet, the relationship between moose FPT and wolf RSF was more pronounced (ave. across seasons: -60.1%) than the Voyageurs National Park ecosystem (-30.4%). These findings highlight the role wolves can play in determining moose behavior, whereby moose spend less time in areas with higher predicted likelihood of wolf resource selection

    Data from: Top-down effects of repatriating bald eagles hinder jointly recovering competitors

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    1. The recovery of piscivorous birds around the world is touted as one of the great conservation successes of the 21st century, but for some species, this success was short-lived. Bald eagles, ospreys, and great blue herons began repatriating Voyageurs National Park, USA, in the mid-20th century. However, after 1990, only eagles continued their recovery, while osprey and heron recovery failed for unknown reasons. 2. We aimed to evaluate whether top-down effects of bald eagles, and bottom-up effects of inclement weather, habitat quality, and fish resources contributed to the failed recovery of ospreys and herons in a protected area. 3. We quantified the relative influence of top-down and bottom-up factors on nest colonization, persistence (i.e., nest reuse) and success for ospreys, and occurrence and size of heronries using 26 years (1986-2012) of spatially-explicit monitoring data coupled with multi-response hierarchical models and Bayesian variable selection approaches. 4. Bald eagles were previously shown to recover faster due to intensive nest protection and management. Increased numbers of eagles were associated with a reduction in the numbers of osprey nests, their nesting success, and heronry size; while higher local densities of nesting eagles deterred heronries nearby. We found little evidence of bottom-up limitations on the failed recovery of herons and ospreys. 5. We present a conservation conundrum: bald eagles are top predators and a flagship species of conservation that have benefited from intensive protection, but this likely hindered the recovery of ospreys and herons. Returning top predators, or rewilding, is widely promoted as a conservation strategy for top-down ecosystem recovery, but managing top predators in isolation of jointly recovering species can halt or reverse ecosystem recovery. Previous studies warn of the potential consequences of ignoring biotic interactions amongst recovering species, but we go further by quantifying how these interactions contributed to failed recoveries via impacts on the nesting demography of jointly recovering species. Multi-species management is paramount to realizing the ecosystem benefits of top predator recovery
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