Sentences with phrase «predator populations in»

Not exact matches

«How fear alone can cause animal extinction: Even the smell of a predator can have disastrous effects in populations of small size.»

Though wolves are on the upswing in these regions, their populations are likely too isolated to control the pervasive coyote and other small predators.

Disrupting a population could also produce ripple effects in other corners of the ecosystem, for example taking a food source from aquatic predators that feed on mosquito larvae.

It is also an apex and keystone predator, playing an important role in stabilizing ecosystems and regulating the populations of prey species.

For the booming moose population of Isle Royale, a key species in the world's longest running predator - prey study on the island, skulls have shrunk by about 16 percent over a 40 - year period.

But the pattern suggests that these natural population controls could be a defining feature of top predators, the authors argue online this month in Oikos.

It is of no immediate concern to caiman populations in South America because the ants and caimans co-evolved there, and natural red fire ant predators, such as the decapitating fly, help keep the ants in check.

In parallel manner, the quantity of elk and moose are the limiting factor for the wolves: When the predator population runs low on food, in this case elk and moose, its population fallIn parallel manner, the quantity of elk and moose are the limiting factor for the wolves: When the predator population runs low on food, in this case elk and moose, its population fallin this case elk and moose, its population falls.

I mean, not every zebra of course have, [having] seen many lions eating zebras — but enough zebras do survive, so that their population continues on and that's pretty much the same down with human beings there, though of course in recent years it has gotten a little more challenging because we've become much more cunning and technologically empowered predators than we were before.

The researchers also found that moose mortality was higher at the edges of an expanding bear population than in the center of the bear population, leading them to conclude that moose with less exposure to predators were more likely to be killed.

In ecological terms, these spiders are marine predators, and this explains how tiny, barren islands can support much denser populations of spiders than lushly vegetated inland areas.

«We are not recommending placing rhino herds in Arizona or polar bears in Antarctica,» the group writes, as, for example, the polar bear would then devastate Antarctic penguin and seal populations that have never encountered such a predator.

Without natural predators, the rat population has swollen to many million, eating their way through tens of millions of ground - nesting birds» eggs and chicks in the process.

The consequences of such initiative were disastrous: Protected from hunting for 35 years, and devoid of natural predators, the beavers grew over 5,000 times their initial population, caused irreversible changes in the forest ecosystem, and started advancing over the continent.

And the researchers have reason to believe this change is in the works: The foxes have been outcompeted by growing populations of coyotes in the regions, which are becoming the top predators in areas where mountain lions and wolves have gone extinct.

For example, the thinning ice is driving melt ponds in the Arctic and promoting phytoplankton blooms under the ice; the warming is also altering population dynamics among lemmings, with, in some locations, dire effects on their predators, such as the Arctic fox.

«In this study, we show for the first time that it is possible to use DNA metabarcoding to generate data on both diet and the predator's population structure.

Knowing that researchers in the early 20th century had shown that avian predators can wipe out an entire population of cicadas that emerges out of sequence, Koenig decided to take a look at how bird populations might affect the insects» cycles.

He found higher rates of nest predation in small woodlots near human communities because these areas had higher populations of raccoons (Procyon lotor) and squirrels (Sciurus spp.) and few, if any, large predators, such as cougars and bobcats (Lynx rufus).

The changes in biomass are worrying, says Michael Hirshfield, chief scientist of the advocacy group Oceana, based in Washington, D.C. Populations of small fish tend to boom and bust — making ecosystems less stable — much more when the ranks of top predators have been gutted.

The problem is that we don't know how much damage the predators do during winter, when the lemming population grows fastest, as, unsurprisingly, researchers do most of their field studies in the summer.

In two of them P. perezi has been co-existing with the red swamp crayfish for more than 30 years (populations of long - term coexistence), in another they have been sharing a habitat for 20 years (population of short - term coexistence), while the last two populations are found in an area which has not yet been colonised by the exotic predator (populations without coexistence),» adds the scientisIn two of them P. perezi has been co-existing with the red swamp crayfish for more than 30 years (populations of long - term coexistence), in another they have been sharing a habitat for 20 years (population of short - term coexistence), while the last two populations are found in an area which has not yet been colonised by the exotic predator (populations without coexistence),» adds the scientisin another they have been sharing a habitat for 20 years (population of short - term coexistence), while the last two populations are found in an area which has not yet been colonised by the exotic predator (populations without coexistence),» adds the scientisin an area which has not yet been colonised by the exotic predator (populations without coexistence),» adds the scientist.

A second population recently established in the predator - free Midway Atoll National Wildlife Refuge is growing rapidly.

Able to adapt to new settings before potential predators had learned to hunt them, they enjoyed a honeymoon period in many places that enabled populations to establish and thrive, says Hughes.

For instance, if a mutation that confers viral resistance in a species of bacteria becomes dominant, that may change the predator - prey relationship by rendering the bacteria population safe from harm.

Rather than conduct experiments of voracious predators chasing and eating, or completely avoiding, prey, the scientists used evolving populations of digital organisms in a virtual world called Avida.

«Evolution in species may reverse predator - prey population cycles.»

The experiments investigated both top - down (driven by predators) and bottom - up (food or resource limited) effects of the lights on the population density of a species of pea aphid, and in the presence and absence of predators including ladybirds.

It may be that in some areas, the most important drivers of tick abundance are the factors that control small mammal populations, including their food supply and predators, Kilpatrick said.

«Monkeys are cute, but can devastate systems that don't have the proper predators or other ecological means to keep their populations in check,» said Jane Anderson, a doctoral student in wildlife ecology and the lead author on this study.

The findings may also explain why harbor seal populations are declining in fjords whose glaciers have retreated onto land: Without the acoustic camouflage provided by the bubble - induced din, the seals may have a harder time evading their main predator, the killer whale.

Unlike previous ones, the new model showed that predator and prey populations fluctuate less in complex food webs — those with long food chains, omnivorous predators, and competing species of plant - eaters.

«Conversely, increases in cephalopod populations could benefit marine predators which are reliant on them for food, as well as human communities reliant on them as a fisheries resource.»

Birds play an important role in a wide variety of ecosystems as both predator and prey, in controlling insect populations, pollinating and seed dispersal for many plants, and in releasing nutrients on to land and sea in the form of guano.

In the late 1980s, the entire remaining population of the parrot was relocated on numerous occasions to various small islands that had to be re-vegetated and made free of feral cats and other predators.

The aphid population, Losey found, fluctuates depending on the type of predator in the area.

And by providing additional refuge from predators, fleshy seaweeds that drift in and out of seagrass beds can maintain larger grazer populations and enhance their positive impact on seagrass.»

Mark Davis from Macalester College in Saint Paul, Minnesota, points out that 86 per cent of the extinctions ascribed to invasive species occurred on islands, where endemic species have small populations and are poorly adapted for predators or environmental changes.

But in the long run, it is unclear if the Arctic ecosystem supports large populations of this voracious predator.

Without a long record, Woith said, researchers can not be sure that their observations relate to an earthquake and not some other kind of environmental change or long - term fluctuation in the health of an animal population or its predators.

This paper by Urban and Richardson presents an elegant series of studies of how foraging rates have evolved in multiple populations of the spotted salamander (Ambystoma maculatum) that coexist with different types of predators.

It's crystal clear that many predators ARE killed by toads — we often find them lying dead with a toad in their mouth or stomach — but the question is, what proportion of the population are killed?

The idea is that Passenger Pigeons evolved to live in huge flocks and became dependent on their large flocks, meaning they could not produce enough offspring to survive unless there were billions of them, either for social reasons (they would not breed in small flocks), for predator reasons (they could not satiate predators without huge flocks), or for resource reasons (they could not find adequate food sources in small populations).

Predator - induced plasticity and morphological trade - offs in latitudinally - separated populations of Littorina obtusata.

We found that PCBs were at excessively high concentrations in the blubber of several marine apex predator species across Europe, including killer whales and bottlenose dolphins, and were associated with long - term and on - going population declines.

May 2, 2011 The winners of mass extinction: with predators gone, prey thrives In modern ecology, the removal or addition of a predator to an ecosystem can produce dramatic changes in the population of prey specieIn modern ecology, the removal or addition of a predator to an ecosystem can produce dramatic changes in the population of prey speciein the population of prey species.

«We thought in a warming Arctic the predators might more eat mosquitoes on any given day, and that the mosquito population might actually go down,» Culler said.

More ominously, the scientists warn that, «If we do nothing, endocrine disruptors may not only impact on human health but all the ecosystems including those on which we depend — if we compromise soil productivity and sustainability of our agricultural systems or cause imbalance in marine and freshwater ecosystems through damage to populations of top predators, ultimately, we threaten our own survival.»

«A Quiet Place» is an amusing title for what turns out to be a meticulously muscle - clenching exercise in gimmicky horror, the type that imagines a future population terrorized by sight - challenged predators who hunt by human noise.

This resource seeks to increase awareness and knowledge of the six deer species now found in the UK, their lifecycle, including predators, the problems associated with their population increase and the effect they have on the habitats they frequent