Seasonal variation in movements and survival of invasive Pacific rats on sub-tropical Henderson Island: implications for eradication

A study on Henderson Island revealed that Pacific rats exhibit significant seasonal variation in survival, with the highest monthly survival probability (0.950) observed in late August and the lowest (0.352) in late July. This temporal pattern suggests resource limitations that could influence the success of eradication efforts. The research used a spatially-explicit Cormack-Jolly-Seber model to estimate movement distances, home range sizes, and survival rates over five months. Rats displayed varied movement behaviors, with some exhibiting 'territorial' (median radius: 134 m) and others 'roaming' (median radius: 778 m) patterns. The proportion of roaming rats fluctuated seasonally, peaking at 23% in October. These findings imply that timing eradication efforts to align with periods of lower survival probability could enhance success.

Veitch, C. R., Clout, M. N., Martin, A. R., Russell, J. C., & West, C. J. (Eds.). (2019). Island invasives: scaling up to meet the challenge. Proceedings of the international conference on island invasives 2017. https://doi.org/10.2305/iucn.ch.2019.ssc-op.62.en