Share this item

Connect with Secretariat of the Pacific Regional Environment Programme (SPREP)

Contact this content partner to get more information about this item.

Recovery of introduced Pacific rats following a failed eradication attempt on subtropical Henderson Island, South Pacific Ocean

Description:
Rodent eradications in tropical environments are often more challenging and less successful than those in temperate environments. Reduced seasonality and the lack of a defined annual resource pulse influence rodent population dynamics differently than the well-defined annual cycles on temperate islands, so an understanding of rodent ecology and population dynamics is important to maximise the chances of eradication success in the tropics. Here, we report on the recovery of a Pacific rat (Rattus exulans) population on Henderson Island, South Pacific Ocean, following a failed eradication operation in 2011. We assessed changes in the rat population using capture rates from snap-trapping and investigated seasonality by using capture rates from live-trapping. Following the failed eradication operation in 2011, rat populations increased rapidly with annual per capita growth rates, r, of 0.48–5.95, increasing from 60–80 individuals to two-thirds of the pre-eradication abundance within two years, before decreasing (r = -0.25 – -0.20), presumably as the population fluctuated around its carrying capacity. The long-term changes in rat abundance may, however, be confounded by short-term fluctuations: four years after the eradication attempt we observed significant variation in rat trapping rates among months on the plateau, ranging from 36.6 rats per 100 corrected trap-nights in mid-June to 12.6 in late August. Based on mark-recapture, we also estimated rat density fluctuations in the embayment forest between 20.4 and 42.9 rats ha-1 within one month in 2015, and a much lower rat density on the coral plateau fluctuating between 0.76 and 6.08 rats ha-1 in the span of two months. The causes for the short-term density fluctuations are poorly understood, but as eradication operations on tropical and subtropical islands become more frequent, it will be increasingly important to understand the behaviour and ecology of the invasive species targeted to identify times that maximise eradication success.
Display date:
2019
Collections:
Secretariat of the Pacific Regional Environment Programme (SPREP)
Publisher:
Secretariat of the Pacific Regional Environment Programme (SPREP)
Content partner:
Secretariat of the Pacific Regional Environment Programme (SPREP)
Availability:
Not specified
Remember or recognise anything about this item? Let us know!

We would love to share your stories, thoughts, and memories on digitalpasifik.org

Contribute your story
Secretariat of the Pacific Regional Environment Programme (SPREP)
Secretariat of the Pacific Regional Environment Programme (SPREP)
Welcome and warm Pasifik greetings

The information on this site has been gathered from our content partners.

The names, terms, and labels that we present on the site may contain images or voices of deceased persons and may also reflect the bias, norms, and perspective of the period of time in which they were created. We accept that these may not be appropriate today.

If you have any concerns or questions about an item, please contact us.