The future delivery of oral contraceptives to control the grey squirrel (Sciurus carolinensis): do age, sex, and reproductive status affect bait uptake? - 1st Workshop on Wildlife Fertility Control: What Now? What Next? Where To? June 17 – 18, 2024 University of York - York, United Kingdom

Author(s)
Cristiano Tiberi
Date Issued
2024
Type
conferenceObject
Abstract
The grey squirrel (Sciurus carolinensis) is classed as an invasive non-native or alien species in the UK and Europe due to its negative impacts. In England and Wales grey squirrel bark stripping damage to ecologically and economically important trees costs the economy at least £37 million a year. Grey squirrels caused major declines of the native red squirrel (Sciurus vulgaris) across the UK and this is also becoming a problem in Italy. Contraceptives delivered through baits are in development to control populations of grey squirrels. We investigated whether sex, age and reproductive status affected bait uptake in four grey squirrel populations in Yorkshire. Squirrels were captured, fitted with a PIT-tag, released, and their feeding behaviour monitored using purpose-designed bait hoppers. Hoppers were baited daily for five days with hazelnut paste mixed with the biomarker Rhodamine B. Squirrels were then recaptured and dispatched. Each squirrel was categorised based on their sex, age and reproductive status. Hair samples from each squirrel were analysed for the presence of Rhodamine B. Overall, 49% of grey squirrels showed positive for Rhodamine B, with sexually active females (67%) consuming more bait than males, juveniles and non-sexually mature animals. An analysis of PIT-tag records showed that squirrel category did not strongly influence time spent feeding from hoppers. However, adult squirrels made fewer daily visits to hoppers and visited fewer hoppers per day than immature squirrels; the variability in number of feeders visited daily and daily visits to hoppers was much greater in immature than in adult squirrels. We conclude that it is possible to deliver bait equally to squirrels of different age, sex and reproductive status, with breeding females more likely to be targeted by baits than other categories. In time, these results could provide information on the administration of oral contraceptives and vaccines when these become available.
Handle
Conference(s)
1st Workshop on Wildlife Fertility Control: What Now? What Next? Where To? June 17 – 18, 2024 University of York - York, United Kingdom