Biodiversity and Conservation

, Volume 24, Issue 10, pp 2551–2563 | Cite as

Application of a non-invasive indexing method for introduced Norway rats (Rattus norvegicus) in the Aleutian Islands, Alaska

  • Alexander L. BondEmail author
  • Cari J. Eggleston
Original Paper


Island restoration projects that address invasive species issues require measures of invader populations before eradication or control efforts begin, especially for cryptic species such as introduced rodents. To address this need, we tested a non-invasive technique for measuring inter-annual variation in Norway rat (Rattus norvegicus) activity at Kiska Island, Aleutian Islands, Alaska, during 2005-2010. Snap-trapping could not be used at a large mixed colony of small seabirds (auklets, Aethia spp.) at Sirius Point, Kiska, due to the certainty of bird mortality. Away from the colony site at Kiska Harbour, in June 2005, we used snap-traps to measure capture rates, and found a similar corrected trap index (8.5 captures/100 trap nights) to that recorded pre-eradication at Langara Island, British Columbia (8.2 captures/100 trap nights). At Sirius Point, we determined the most effective rat-monitoring method to be a series transects spanning the auklet colony, with detection stations set at 25 m intervals, each including a baited wax block. Rat detections varied nearly 100-fold among years, suggesting high inter-annual variability in the rat population. We found no statistically significant relationship between our rat index and auklet breeding success at Sirius Point with our small sample of years (n = 5, 2006–2010). Nevertheless, we believe rat numbers were much lower at Sirius Point during 2006–2010 than observed qualitatively during 2001–2002 when auklets experienced breeding failure. Our rat activity index protocol is likely applicable to other situations in which introduced rodent numbers needs to be monitored while safeguarding native fauna that could be harmed by snap-trapping.


Rattus norvegicus Relative abundance Seabird Auklet Aleutian Islands Restoration 



Assistance in the field was provided by C. P. Brake, J. Dussureault, C. Eggleston, I. Jones, E. E. Penney, D. W. Pirie-Hay, G. M. Samson, K. Shea, and M. Wille. This project was made possible by the support from Alaska Maritime National Wildlife Refuge, including transportation and logistical support provided by M/V Tiĝla \(\hat{x}\), and particularly G.V. Byrd and J.C. Williams. Financial support was provided by the Natural Sciences and Engineering Research Council of Canada, North Pacific Research Board, Alaska Maritime National Wildlife Refuge and the Northern Scientific Training Program of the Department of Aboriginal Affairs and Northern Development of Canada. This manuscript was improved by comments from I. Jones, and anonymous reviewers.

Supplementary material

10531_2015_944_MOESM1_ESM.doc (121 kb)
Supplementary material 1 (DOC 121 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  1. 1.Department of BiologyMemorial University of NewfoundlandSt. John’sCanada
  2. 2.RSPB Centre for Conservation ScienceRoyal Society for the Protection of Birds, The LodgeSandyUK

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