Occupancy surveys are widely used in ecology to study wildlife and plant habitat use. To account for imperfect detection probability many researchers use occupancy models. But occupancy probability estimates for rare species tend to be biased because we’re unlikely to observe the animals at all and as a result, the data aren’t very informative.
Britain’s smallest bird species, the goldcrest, is being hit hard by cold winters, new analysis methods developed by researchers at the University of St Andrews have revealed.
The data analysis techniques, published today in Methods in Ecology and Evolution, take a longer term view over multiple locations and for a period of several years, compared to previous studies.
They showed that the cold temperatures strongly affected breeding numbers of the goldcrest, while in contrast, the song thrush was not affected by the cold, but benefited from wet and mild summers. Continue reading →
Whether you are a laboratory or a field scientist, you have to be willing to get your hands dirty from time to time for the good of science. Sarah and I took that literally and spent a large part of our respective PhD projects handling faeces of free-ranging spotted hyenas from the Serengeti National Park and the Ngorongoro Crater, Tanzania.
Though faeces often are underrated, they are highly valuable material to work with because they conceal the most secret details about an animal’s social and sexual life. But having the privilege of holding a still-steaming poop is something you have to earn! Continue reading →
Flaws in a method commonly used in censuses of tigers and other rare wildlife put the accuracy of such surveys in doubt, a new study suggests.
A team of scientists from the University of Oxford, Indian Statistical Institute, and Wildlife Conservation Society exposes, for the first time, inherent shortcomings in the ‘index-calibration’ method that means it can produce inaccurate results. Amongst recent studies thought to be based on this method is India’s national tiger survey (January 2015) which claimed a surprising but welcome 30 percent rise in tiger numbers in just four years.
The team urges conservation practitioners to guard against these sources of error, which could mislead even the best conservation efforts, and suggests a constructive way forward using alternative methods of counting rare animals that avoid the pitfalls of the index-calibration approach.