Aberdeen with Radiotelemetry

In 1977, Pounds (1981) began his doctoral studies at the same field station where Moors had struggled to make sense of weasel biology only a few years before. Pounds had the advantage of having many basic problems already solved; the techniques of live trapping and of maintaining weasels in captivity were by then almost routine, and he also had a fair idea of the distribution and diet of the local weasels from Moors' work. But he was one of the first to apply radiote-lemetry to weasels, so he was able to follow individual animals around their ranges and observe their movements and interactions with each other at a level of detail that previous workers could only dream about.

In the winters of 1977-1978 and 1978-1979, Pounds fitted seven male and two female common weasels with radios and tracked each for up to 28 days. As expected, they all used the stone walls, field margins, and rough grassland along fence lines around the fields, avoiding the open fields. Each had two to five den sites that it used frequently and three to ten occasionally used resting places scattered along its regular routes. Each had several favorite hunting areas and would stay in one for a while and then set off on an apparently purposeful straight-line excursion to another one. The weasels could be active at any time, but the longer trips were undertaken more often by day than by night. Some hunting areas were exclusive, although ownership could transfer, and others were shared, although not at the same time. Pounds watched one male hunting in an open turnip field during the harvest, running along the rows, pouncing on the small rodents disturbed by the workers.

The total areas calculated for the winter home ranges of these common weasels were very large. Those of the seven males averaged 34 ha, and those of the two females, 38 and 12 ha. But the "exploitable ranges" (i.e., excluding the generally unused open fields) were 2.4 ha for males and 1.2 ha for females. The difference between the figures given by Moors and by Pounds for weasels observed in the same area only a few years apart (Table 8.1) is due to the difficulty of deciding how large a boundary strip to allow along the field edges. Consistent with all previous studies using only the clumsier method of live trapping, Pounds confirmed that females occupied smaller areas than males, that weasels traveled surprising distances in short times, and that they avoided directly meeting each other but were quick to replace each other in possession of favorable ground.

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