2,409 research outputs found
Redistribution, Human Shields and Loss of Migratory Behavior in the Crown of the Continent
Redistribution of wildlife resulting from human alteration of environments is of growing management concern in North America. Habituation, which can coincide with redistribution, seems to be particularity prevalent in national park systems because millions of visitors interact with wildlife. For example, Glacier National Park in northwestern Montana, USA, receives approximately 2.2 million visitors over the months of June, July, and August each year—with the majority of their activity concentrated along the Going-to-Sun Road. The Going-to-Sun Road corridor is well-known for its habituated mountain goats (Oreamnos americanus). Habituation, however, was identified as a priority management concern in Glacier National Park. Successful management actions require a clear understanding of the causes and consequences of complex ecological issues such as habituation. Through experimental and observation effort this project has identified human-created predation refugia, or human shields, where mountain goats are escaping predation through interaction with people. Reductions in predation risk have resulted in mountain goat redistribution and changes in behavior. We found mountain goats using sites with human shields were less vigilant and were found in smaller groups. Furthermore, goats in areas with human-mediated predation refuge had reduced use cliff security terrain. Additionally, mountain goats that exploited people as shields from predators showed a weakened response to an experimentally presented predator model. Reductions in predator risk appear to be the primary driver of mountain goat redistribution and the use of humans as buffers from predation has led to close contact between people and wildlife, resulting in compromised safety and altered ecological interactions
\u3ci\u3eLockett\u3c/i\u3e Symposium: Recollections on the \u3ci\u3eLockett\u3c/i\u3e Case in the U.S. Supreme Court
Recollections of an NAACP Legal Defense Fund attorney who worked with Professor Amsterdam on the Lockett case
Undetected Species Losses, Food Webs, and Ecological Baselines: a Cautionary Tale from the Greater Yellowstone Ecosystem, USA
Large protected areas are often considered natural yet outside pressures may compromise ecological integrity. This paper points to a problem in assessing ecological baselines: what if species\u27 extirpations go undetected? I present a data set spanning 130 years that demonstrates the loss of white-tailed jack rabbits Lepus townsendii from two National Parks in the well studied 60,000 km(2) Greater Yellowstone Ecosystem, USA. While these extirpations have been unnoticed until now, an ecological consequence may be elevated predation on juvenile ungulates. A critical challenge we face is how to apply better the concept of shifting baselines to the restoration of functional relationships when species\u27 losses are undetected
Indirect Effects and Traditional Trophic Cascades: a Test Involving Wolves, Coyotes, and Pronghorn
The traditional trophic cascades model is based on consumer - resource interactions at each link in a food chain. However, trophic-level interactions, such as mesocarnivore release resulting from intraguild predation, may also be important mediators of cascades. From September 2001 to August 2004, we used spatial and seasonal heterogeneity in wolf distribution and abundance in the southern Greater Yellowstone Ecosystem to evaluate whether mesopredator release of coyotes ( Canis latrans), resulting from the extirpation of wolves ( Canis lupus), accounts for high rates of coyote predation on pronghorn ( Antilocapra americana) fawns observed in some areas. Results of this ecological perturbation in wolf densities, coyote densities, and pronghorn neonatal survival at wolf-free and wolf-abundant sites support the existence of a species-level trophic cascade. That wolves precipitated a trophic cascade was evidenced by fawn survival rates that were four-fold higher at sites used by wolves. A negative correlation between coyote and wolf densities supports the hypothesis that interspecific interactions between the two species facilitated the difference in fawn survival. Whereas densities of resident coyotes were similar between wolf-free and wolf-abundant sites, the abundance of transient coyotes was significantly lower in areas used by wolves. Thus, differential effects of wolves on solitary coyotes may be an important mechanism by which wolves limit coyote densities. Our results support the hypothesis that mesopredator release of coyotes contributes to high rates of coyote predation on pronghorn fawns, and demonstrate the importance of alternative food web pathways in structuring the dynamics of terrestrial systems
Responsive Urban Renewal: The Neighborhood Shapes the Plan
Only massive infusions of federal subsidy, encouragement, and prodding can stimulate the private and local governmental action needed to rebuild our nation\u27s cities. We must expand, not contract, urban the renewal program
Resource Selection, Predation Risk, and Underestimates of Refuge Habitat for an Alpine Obligate
Understanding relationships between animals and their habitat is a central goal in ecology with important implications for conservation. Misidentified habitat requirements, however, can have serious repercussions because land protections or reintroductions might occur in areas of less than optimal habitat. Studies of resource selection have greatly facilitated an understanding of relationships but suffer because rarely used, but vital habitat features may be insufficiently described. A critical element for many prey species is escape terrain or some form of refuge. Mountain goats (Oreamnos americanus) are a species well known for their use of cliffs to escape predation, but a survey of the literature reveals at least twelve different approximations of goat escape terrain. Here, we sought to 1) optimize mountain goat escape terrain estimates, and 2) highlight the assumption that the time an animal spends in an area is proportional to importance. We experimentally exposed mountain goats to grizzly bear (predation risk) and ungulate (control) imitations and recorded subsequent escape locations in Glacier National Park, Montana, USA. Through a used-unused resource selection function we tested 21 landscape variables for explaining goat escape terrain. We found that distance to slopes greater then 60o best explained where mountain goats fled. Additionally, we identified the need to incorporate behavior and predator interactions into resource selection studies. With 27 failed mountain goats reintroductions these results have consequences on habitat characterization and considerations for species restoration. Managers should consider the availability of escape habitat when protecting land or reintroducing prey species
The superluminous supernova SN 2017egm in the nearby galaxy NGC 3191: a metal-rich environment can support a typical SLSN evolution
At redshift z=0.03, the recently-discovered SN 2017egm is the nearest Type I
superluminous supernova (SLSN) to date, and first near the center of a massive
spiral galaxy (NGC 3191). Using SDSS spectra of NGC 3191, we find a metallicity
~2 Z at the nucleus and ~1.3 Z for a star forming region at a
radial offset similar to SN 2017egm. Archival radio-to-UV photometry reveals a
star-formation rate ~15 M yr (with ~70% dust-obscured), which
can account for a Swift X-ray detection, and stellar mass ~
M. We model the early UV-optical light curves with a magnetar
central-engine model, using the Bayesian light curve fitting tool MOSFiT. The
fits indicate ejecta mass 2-4 M, spin period 4-6 ms, magnetic field
(0.7-1.7)G, and kinetic energy 1-2 erg. These
parameters are consistent with the overall distributions for SLSNe, modeled by
Nicholl et al (2017), although the derived mass and spin are towards the low
end, possibly indicating enhanced loss of mass and angular momentum before
explosion. This has two implications: (i) SLSNe can occur at solar metallicity,
although with a low fraction ~10%; and (ii) metallicity has at most a modest
effect on their properties. Both conclusions are in line with results for long
gamma-ray bursts. Assuming a monotonic rise gives an explosion date MJD
. However, a short-lived excess in the data relative to the
best-fitting models may indicate an early-time `bump'. If confirmed, SN 2017egm
would be the first SLSN with a spectrum during the bump-phase; this shows the
same O II lines seen at maximum light, which may be an important clue for
explaining these bumps.Comment: Accepted for publication in ApJ
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