Animal Pest Field Trial Reporting Template

Transcription

1 Animal Pest Field Trial Report for Efficacy of DOC 200 versus Victor Professional Rat traps at catching rats in the Mangaone Core Area of the Te Urewera Mainland Island September 2004 June 2006 Anastacia Kirk June 2007 Opotiki Area Office Cnr St John & Elliott Streets Opotiki New Zealand Appendix 4 Report template Page -1- QD Code: NH3012

2 1. Field trial summary The objective of this study was to compare the trapping effectiveness of Victor Professional rat traps set in current best practice coreflute trap tunnels, with DOC200 traps set in a single set wooden trap tunnel. A comparison was made between each trap for catchability (determined by the number of rats caught), trap ability (age and gender differences of those rats which are killed), escapability (measured by the number of escapes), and interference (incidence of disturbance of the trap by non-target species, such as possums and pigs). Seventy-one DOC200 traps in single set wooden trap tunnels were placed every 50 metres along a 5.68km trap line. Similarly, 71 single set Victor Professional rat traps in current best practice coreflute tunnels were placed every 50 metres along the same section of trap line, alternately with a DOC200 trap. In effect, every 25 metres along the line, either a DOC200 or a Victor Professional kill traps was encountered. The DOC200 performed well in terms of catchability with a proportionally higher catch rate than the Victor Professional. This would indicate that improved rat kill trapping results can be achieved with DOC200 s in single set wooden tunnels, in comparison to Victor Professional rat traps in coreflute tunnels. 2. Introduction The efficiency of rat control by kill trapping is determined by a number of variables. Such variables include the ability of a rat trap to kill effectively with few escapes; traps that are not prone to interference from non-target pest species such as possums and pigs; and that the ability of a trap to catch a rat is not dependent on a rat s sex or age. A further consideration is that rat control must be cost-effective over a broad-scale application. Rat control is an integral component of an ecosystem restoration operation underway in the northern area of Te Urewera National Park. Ship rat (Rattus rattus) is the predominant rat species and is known to predate on, and to compete for food supply, with vulnerable species such as kiwi and kokako (Brown 1994, Beaven, Harrison, & Shaw 1999). Rat control by kill trapping is primarily undertaken during the breeding season of kokako. In the 2004/05 operational year, 10,793 ship rats were caught in kill traps within five core areas encompassing 6159ha. Current practice within the cores areas is to place Victor Professional rat kill traps inside plastic coreflute tunnels, every 25m along trapping lines. Trapping lines generally follow contour, ridges and spurs. The core areas differ in trapping line configuration from one line (A) to three lines (A, B C). Where there is more than one line, these are placed 150m apart. To date no study has been conducted on the effectiveness of DOC200 traps to kill ship rats compared with other types of rat kill trap. However, a trial conducted comparing the effectiveness of Fenn Mark VI versus DOC200 for killing stoats, found that 211 ship rats were caught in DOC200 s, and 142 in Fenn traps indicating that the DOC200 performed significantly better than the Fenn (Open Space 2006). The objective of this study is to compare the trapping effectiveness of Victor Professional rat traps set in current best practice coreflute trap tunnels, with DOC200 traps set in a single set wooden trap tunnel. A comparison will be made between each trap for catchability (determined by the number of rats caught), trap ability (age and gender differences of those rats which are killed), escapability (measured by the number of escapes), and interference (incidence of disturbance of the trap by non-target species, such as possums and pigs). Appendix 4 Report template Page -2- QD Code: NH3012

3 3. Trial design The trial took place between September 2004 and June 2006 within the Mangaone inner core area (232ha) in the northern area of the Te Urewera National Park (see Appendix 1 for map). The vegetation is a broadleaf-podocarp mix dominated by tawa (Beilschmiedia tawa). Intensive pest control is carried out in this area as it supports a small population of endangered North Island kokako (Callaeas cinerea wilsoni). The terrain consists of steep sided ridges and spurs, with a maximum elevation of 706 metres. Seventy-one DOC200 traps (Curtis Metal Products Ltd, Otahuhu, NZ) in single set wooden trap tunnels (Haines Pellet Co Ltd, Seaview, NZ) were placed every 50 metres along a 5.68km, west facing section of the Mangaone inner core area boundary. The trapping line runs 150 metres below and parallel to the main ridgeline. Similarly, 71 single set Victor Professional rat traps (Woodstream Corporation, Lititz, USA) in current best practice coreflute tunnels i.e. coreflute cover over a wooden base, with a 40mm diameter entrance hole, and a wire mesh hinged access door, were placed every 50 metres along the same section of A line, alternately with a DOC200 trap. In effect, every 25 metres along the line, either a DOC200 or a Victor Professional kill traps was encountered. A coin was flipped to determine which trap type began the sequence. All traps, coreflute trap covers, and wooden trap boxes were new. During the trial, both trap types were tested at regular intervals to assess spring off weights. Each trap was required to spring off at 40gms or below, in order to catch a rat. Each trap was baited with white chocolate buttons, and were rebaited when each trap was checked every two weeks during the period from November 2004 to February Each session that the trial trap line was checked the operator recorded: the date the trap line was checked the name of the operator the status of the trap e.g. SPRB = sprung no catch and bait taken (see Appendix 2 for a full description of data entry notation) date any bait was replaced species and sex of the caught rat any supplementary observations noted by the operator which might have a bearing on the trial e.g. trap springs becoming rusty or weak Data was analysed using binary logistic regression, CHAID analyses, and Chi² tests using SPSS statistical software. Results Nineteen trap checking rounds were conducted between 9 th November 2004 and 9 th February The Victor trap caught 172 rats over the trial period (mean 2.42 ± 0.18 SE rats per trap). The DOC200 trap caught 218 rats over the same period (mean 3.07 ± 0.17SE rats per trap). The proportion of DOC200 traps that caught a rat(s) was significantly higher than the proportion of Victor traps that caught a rat(s); Pearson χ 2 =3.873 df=1, Exact p=0.048 (1 tailed). Both the DOC200 and Victor traps caught non-target pest species. The DOC200 caught three stoats, and seven mice, whilst the Victor trap caught 12 mice, but no stoats. Neither trap caught any non-target native species including passerines, or any other exotic bird species. Appendix 4 Report template Page -3- QD Code: NH3012

4 Escapes were recorded where the trap had been sprung off and the bait was present (DOC200-35; Victor 27), and where the trap had been sprung and the bait taken (DOC200 40; Victor 38). There was no significant difference in escapes between the two traps. One hundred and forty DOC200 and 73 Victor Professional traps remained set, but had the bait taken during the course of the study. The higher number of DOC200 s in this case was heavily influenced by one check. However, when compared on a check-per-check basis the difference between traps was not significantly different (Mann-Whitney U=147.5, p=0.157). It had only been possible to identify the sex of a small number of rats, and on account of the insufficient amount of data, the sex differences in trap catch were not analysed. 4. Discussion Rat control has been undertaken during the bird breeding season in the NTUERP since It is widely accepted that the reduction of rat population density to a 5% tracking index allows vulnerable species such as the North Island kokako (Calleaus cinnera wilsonii) to survive without adverse predation and competition for food. The DOC200 caught a greater proportion of rats than the Victor trap, indicating that the DOC200 is superior to the Victor in terms of catchability. Despite this encouraging result, the DOC200 did less well where the bait was taken, yet the trap remained set. During 1394 trap nights, this occurred 140 times in the DOC200 s, and 73 out of 1394 Victor trap nights. It is difficult to determine why the DOC200 should perform less well in this instance. One possible reason may be that the trigger mechanism was not set finely enough to be sufficiently sensitive to detect rat weight. A further possible reason may be that there was interference of bait by mice which would be in keeping with the potential difficulty the trap has in detecting lighter weight target species. However, the number of mice caught by both the Victor and DOC200 was not significantly different, indicating that the DOC200 is sensitive to mice weight, and that the loss of bait can not necessarily be attributed to this. Bait loss is known to occur not only due to interference by mice, but from ants, wetas and other ground dwelling invertebrates. It may be that invertebrates and mice prefer the wooden box surround, as opposed to the plastic coreflute, and this could be investigated further. With a DOC200 set at a spring off weight able to prevent mice capture and a caged bait placed beyond the trap, there may be potential to increase the effectiveness of the DOC200. Each trap performed at a similar level in terms of trap escapes, that is, where the trap had been sprung and where the bait had either been taken, or remained. It is not possible to determine the effectiveness of a trap by escapes alone, however it is reassuring that the number of escapes was low in relation to overall trap nights. Drickamer et al (1999) found that male and female mice (Mus musculus) displayed different levels of trap ability, with females in particular either being trap-prone or trap-shy. Unfortunately, no significant difference in the sex ratio of male and female ship rats could be determined as there was insufficient data due to the difficulties in sexing decomposed carcasses, and possible inexperience of the field recorders in identifying sex. Differences in the trap ability of juvenile and adults was not investigated in this study, yet there is evidence that age may contnbute to trap ability in mice at least (Drickamer et al 1999). To ascertain trap ability is complex and can not solely be attributed to factors such as sex and age. Other parameters such as habitat type, population density, odour from previous inhabitants (Heske 1987), and weather may too be influential. To obtain a truer indication of trap ability, these parameters should be recorded, and the data analysed using a correlative statistical test. Appendix 4 Report template Page -4- QD Code: NH3012

5 Field recorders noted that the wooden tunnels containing the DOC200 traps appeared to be less prone to disturbance by possums and pigs compared to the Victor Professionals in coreflute tunnels. There was however insufficient data to determine if the observed difference was significant. Information on the habitat type where traps were located would have been useful as it could have provided an insight into the preferred habitats of rats. However, this information was not required for the purposes of this study as it simply aimed to determine whether a trap type caught a target animal - not the number of times it did so. This method of analysis also removed any bias attributable to trap location and/or previous target animal captures. 5. Recommendations The DOC200 performed well in terms of catchability with a proportionally higher catch rate than the Victor Professional. This would indicate that improved rat kill trapping results can be achieved with DOC200 s in single set wooden tunnels, in comparison to Victor Professional rat traps in coreflute tunnels. A further study comparing each trap type in either coreflute or wooden tunnels could be conducted in order to definitively conclude that increased trap kill was attributed to the trap type and not tunnel type. To reduce interference of bait and spring off by mice, the DOC200 could be fitted with a mouse proof bait cage to see if this increases rat catch rates, and this would be worth investigation. Poutu and Warburton (2005) stressed the importance of proper maintenance and setting of DOC200 s in order to obtain maximum trap performance. Operators should be made aware of this, and regular spring off weight checks should be undertaken during trapping programmes. Trap placement in habitats known to be preferred by ship rats should also be considered if known. Overall, the results of this study are promising, with the DOC200 outperforming the Victor Professional. 6. References Source/ Author Year Document Beaven BM, Harrison A, Shaw P 1999 Northern Te Urewera Ecosystem Restoration Project, Te Urewera National Park, July 1997-June East Coast/Hawkes Bay Conservancy, Department of Conservation, Gisborne Brown K 1994 Predation at North Island robin (Petroica australis longipes) and North Island tomtit (Petroica macrocephala toitoi) nests. Unpublished MSc thesis, University of Otago Clapperton BK 2006 Rodent behaviour in relation to control devices. Science for Conservation 263. Department of Conservation: Wellington Drickamer LC 1999 Trap-response heterogeneity of house mice (Mus musculus) in outdoor enclosures. Journal of Mammology 80: Open Space 2006 Pests. Open Space: Magazine of the Queen Elizabeth II National Trust. Issue 68: Tew TE, Todd IA, MacDonald DW 1994 Temporal Changes in Olfactory Preference in Murid Rodents Revealed by Live-Trapping. Journal of Mammalogy 75: Appendix 4 Report template Page -5- QD Code: NH3012

6 7. Costs RESOURCE CODE DESCRIPTION APPROVED BUDGET TOTAL $ $ 8. Acknowledgements ACTUAL COSTS EXPLANATION Lindsay Wilson for study design and field operation management, Darren Peters for study design and expert advice, Craig Gillies for statistical analysis, Daniel Baigent for field supervision, and Keith Beale for field work. Comment [N2]: List specific items approved in budget. Comment [N4]: Give actual cost for each item in description. Comment [N5]: Explain any differences between budgeted and actual costs. Comment [N1]: Give the resource code number from DOC work plan / DOC Fin report. Comment [N3]: Give budgeted cost for each item in description. 9. Approval/signoff Peer reviewers names: Area Managers Name: Signature: Date: / / Appendix 4 Report template Page -6- QD Code: NH3012

7 Appendices Previous operational and trial report(s) Work Plan AEE Application for Department of Conservation consent to use pesticides Result monitoring report Outcome monitoring report Trial Data N/A N/A Map of the treatment area Appendix 1 Other Appendix 2 Comment [N6]: Title of report. State DME number (e.g. HAMRO ) and/or file details (e.g. ANI5033) Comment [N7]: Title of workplan. State file details where workplan is held (e.g. ANI5033) Comment [N8]: Title of AEE. State DME number (e.g. HAMRO ) and/or file details (e.g. ANI5033) Comment [N9]: Title of application. State DME number (e.g. HAMRO ) and/or file details (e.g. ANI5033) Comment [N10]: Title of report. State DME number (e.g. HAMRO ) and/or file details (e.g. ANI5033) Comment [N11]: Title of report. State contact name for outcome monitoring and contact details. Replace with DME number and/or file details when report becomes available. Comment [ptw12]: State DME number (e.g., HAMRO 23452) and/or file details (e.g., ANI ). Appendix 4 Report template Page -7- QD Code: NH3012

8 APPENDIX 1 Map of the Mangaone core treatment area, Te Urewera National Park Appendix 4 Report template This copy printed on 1/30/2008 4:21 PM Page -8QD Code: NH3012 doc200vvictorrattrap.doc

9 APPENDIX 2 Data entry notation Data entry notation Validation list s bp stoat weasel rat mouse other spr nb spr bp s nb not set Sex M F UK Condition Fresh Rotten Very rotten What it stands for Trap was set with bait present Trap was sprung and caught a stoat Trap was sprung and caught a weasel Trap was sprung and caught a ship rat Trap was sprung and caught a mouse Trap was sprung and caught some other animal Trap was sprung and the bait was taken Trap was sprung with bait present Trap was set and the bait was taken Trap was not set or not present animal is a male animal is a female cannot determine sex animal fresh - little or no decay animal rotten - started to decay and lose form animal is very rotten - little flesh remaining or skeletonised Appendix 4 Report template Page -9- QD Code: NH3012