Sentences with phrase «predation rate estimates»

We excluded studies from outside temperate regions and those with predation rate estimates based on fewer than 10 cats, < 1 month of sampling, or on cats that were experimentally manipulated (for example, by fitting them with bells or behaviour altering bibs).

Studies were only included if: (1) they clearly reported cat ranging behaviour (that is, a description of whether cats were owned or un-owned and whether they were outdoor cats or indoor - outdoor cats), and (2) the group of cats investigated fit exclusively into one of the two groups we defined above (that is, we excluded studies that lumped owned and un-owned cats in a single predation rate estimate).

Despite the scarcity of direct observations, evidence for the existence of large arctic cod aggregations in winter was traditionally derived from the intensive predation rate estimated from the stomach content of marine mammals and birds later in the season (Welch et al. 1992).

Not exact matches

Marra and his colleagues extrapolated findings from 21 studies in the U.S. and Europe to come up with an estimate of 30 million to 80 million «unowned» cats and 84 million «owned» cats in the U.S., their kill rates, and other factors leading to bird predation.

``... the ecological and conservation significance of these kill tallies is difficult to contextualise, because (1) there are no reliable estimates of the total population of birds in Australia; (2) predation may fall disproportionately on some bird species; (3) some bird species may be able to sustain high mortality rates and maintain viable populations but others may not; and (4) as demonstrated here, there is substantial spatial variation in the numbers and proportion of birds killed across Australia.»

This study by Environment Canada scientist Peter Blancher was designed to create a credible estimate of the rates of bird predation by cats, identify information...

The two inflated figures described in (1) and (2) are multiplied together, further inflating estimated predation rates.

So, whereas Dauphiné and Cooper (and others) suggest increasing such estimates by factors of two and three («predation rates measured through prey returns may represent one half to less than one third of what pet cats actually kill...» [14]-RRB-, they should, in fact, be reducing them by half.

So, even setting aside the complexities of source - sink dynamics, these inflated predation rates, combined with the fact that «the estimates of breeding density presented in this manuscript should be regarded as minima,» [3] raise serious doubts about whether the site is in fact a habitat sink (or, if so, to what extent).

This greatly overestimates potential predation, and leads them to conclude — erroneously — that the actual number of prey killed by cats was «3.3 times greater than the rate estimated from prey brought home,» [9] as was discussed previously.

In their recently released book, The American Bird Conservancy Guide to Bird Conservation, ABC changes tack a bit — using what the authors call «conservative» estimates of the outdoor cat population and annual predation rates, for example, to arrive at their figure of «532 million birds killed annually by outdoor cats.»

Our finding that un-owned cat population size and predation rate explained the greatest variation in mortality estimates reflects the current lack of knowledge about un-owned cats.

Mean predation rates within each square each season were multiplied by cat density to estimate the total number killed, and summed across seasons to estimate the number killed annually.