Breeding suppression in freeranging greysided vo

Authors: Olaf Fuelling Stefan Halle

Publish Date: 2003/10/24

Volume: 138, Issue: 1, Pages: 151-159

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Abstract

The breeding suppression hypothesis predicts that females of certain small mammal species will reduce reproduction as a response to the odour of a specialised mammalian predator This was tested in a field experiment with greysided voles Clethrionomys rufocanus during three summer seasons 1997–1999 in the subalpine tundra of northern Norway which is a natural habitat of this species In a first phase freeranging voles in six unfenced 1ha plots were monitored by livetrapping from June to August each year In a second phase from August to September three of the plots were sprayed with weasel Mustela nivalis odour to simulate increased apparent predation risk while the remaining three plots served as untreated controls On all plots voles were individually marked with ear tattoos and were regularly livetrapped during the whole breeding season to follow their performance On the treatment plots the recruitment rate of juveniles did not increase in late summer as it did on the control plots The proportion of reproductively nonactive adult females was significantly higher on the treatment plots for both old and young females Our results thus verify the breeding suppression hypothesis for the first time under natural conditions However the response in overwintered females is in conflict with the original hypothesis because the assumed fitness benefits from breeding delayed until the next season are inaccessible to them As an alternative explanation we propose a shortterm response of reduced activity and interrupted breeding until the predator has exploited and left the feeding patch Such a “duck and cover” strategy would increase the fitness of females of all age classes when prey habitats are patchyWe thank Tarja and Lauri Oksanen for their invitation to work in their study area and for many fruitful discussions and Britta and Helge Romsdal for their hospitality at Joatka Fjellstue We are especially grateful to Janne Sundell for providing us with the disreputable output of his weasels and to the post office at Alta for storing the smelly packages until we could collect them Michael Depka Katre Eplor Oskar Eriksen Helmut Fuelling Michael Hühn Elke Lindner Jonas Richter Sönke Weinert and Alexander Wolf assisted the field work and helped us fighting the mosquitoes Particular thanks go to Hannu Ylönen for helpful comments and discussions about breeding suppression and to Andrew Davis John Slogett Vicky Temperton Marcio Fattorini Blandine Massonnet and anonymous reviewers who commented on the manuscript The study was financially supported by the German Research Council DFG grants HA 1513/91 and HA 1513/92

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