Penning prior to release decreases post-translocation dispersal of jewelled geckos

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1 bs_bs_banner Penning prior to release decreases post-translocation dispersal of jewelled geckos C. D. Knox 1 & J. M. Monks 2 1 EcoGecko Consultants Ltd, Dunedin, New Zealand 2 Department of Conservation, Dunedin, New Zealand Animal Conservation. Print ISSN Keywords dispersal; hard release; penning; release method; reptile; soft release; translocation; Naultinus gemmeus. Correspondence Carey D. Knox, EcoGecko Consultants Limited, 4 Auld St, St Kilda, Dunedin, Otago 9012, New Zealand carey@ecogecko.co.nz Editor: John Ewen Received 6 September 2013; accepted 5 February 2014 doi: /acv Abstract Translocation is an essential conservation tool often used to re-establish reptile populations following anthropogenic extirpation, but is not always successful. One factor potentially limiting success is dispersal of individuals from the release site immediately after translocation and consequent non-overlap of ranges. Penning involves the use of an enclosure to restrict dispersal of translocated animals for a pre-determined period of time, with the aim of habituating animals to the release site so that they will establish a breeding population. We evaluated the utility of penning for limiting post-translocation dispersal of jewelled geckos (Naultinus gemmeus) by simultaneously tracking 19 geckos that had either been translocated into a pen for 9 10 months prior to the pen s removal (n = 10) or were translocated to a nearby site with no physical barrier to dispersal (n = 9) over a 3-week period. The area occupied by penned geckos did not increase following removal of their pen, despite suitable habitat being available outside the pen area. In contrast, un-penned geckos moved distances of up to 40 m outside of their release area, and effectively increased the area that they were occupying as a group 4.4-fold over the 3-week period. We suspect that when Naultinus geckos are released without time in a pen, some individuals may disperse too far to contribute to a breeding population and, consequently, the likelihood of population establishment and rate of population growth may be diminished. Our hypothesis is supported by a survey we conducted the following summer in which all four adult female geckos found at the penned site were gravid, but neither of the females resighted at the un-penned site was gravid. We believe that the potential advantages of penning (e.g. restricting initial dispersal, increased ease of monitoring) may outweigh the disadvantages (e.g. cost) for many herpetofauna translocations. Introduction The reintroduction of species within their historical range is a technique regularly used by conservation managers and the discipline of reintroduction biology has evolved over the past two decades (Seddon, Armstrong & Maloney, 2007; Ewen et al., 2012). Translocation is now well used as a conservation tool and the number of reintroduction projects undertaken each year continues to grow (Seddon, Strauss & Innes, 2012). However, a recent review of species reintroduction projects finds that a lot of the research in this field is still retrospective in nature and relies on post-hoc interpretation of monitoring results (Seddon et al., 2007). Translocations of herpetofauna have received less scientific attention than those of mammals and birds (Germano & Bishop, 2008) and an early review suggested that low success rates (19%) in translocations of amphibians and reptiles meant that these taxa may not be suitable candidates for translocation (Dodd & Seigel, 1991). Promisingly, success rates of herpetofauna translocations have increased over the past two decades (to 41%; Germano & Bishop, 2008). However, a recent review has highlighted the need for research on how to improve site fidelity of translocated individuals in order to further improve success rates of herpetofauna translocations (Germano & Bishop, 2008). This is particularly important for species which frequently need to be translocated and/or where previous translocations appear to have been unsuccessful. Translocation strategies are often categorized as hard or soft releases (Griffith et al., 1989; Clarke, Boulton & Clarke, 2002; Germano & Bishop, 2008). However, these terms can sometimes be misleading. Soft release was originally used to describe procedures aimed at easing the transition of animals to the release site (e.g. provision of food, water and/or shelter to reduce starvation or predation; e.g. Wanless et al., 2002; Hardman & Moro, 2006); whereas hard release refers to the translocation of animals without measures to ease their transition. However, some 18

2 C. D. Knox and J. M. Monks Penning reduces dispersal in translocated geckos researchers have associated soft release exclusively with temporary confinement of animals in enclosures ( penning ) irrespective of whether or not it is hypothesized to aid their transition to the wild (e.g. Treglia, 2010). This leads to confusion as to whether a release which uses a pen or aviary, but does not include any measures to ease the animal s transition to the release site (e.g. supplementary food or nest boxes) should be termed a hard or soft release. To avoid this confusion, we use more explicit terms penning or penned release to describe a release strategy involving temporary confinement of animals in an enclosure to restrict their initial dispersal, and also refer to supplementary feeding (or other soft-release measures) explicitly when they are discussed. Enclosures such as pens or aviaries are often used to restrict dispersal for a predetermined period of time following translocations with the aim of habituating animals so that they form stable territories in the release area (Bright & Morris, 1994; Letty, Marchandeau & Aubineau, 2007). In cases where initial dispersal is not controlled and animals are released into extensive habitat, animals may disperse in different directions, and then fail to find each other to reproduce. An important assumption underlying the use of pens or aviaries is that post-translocation dispersal will be limited (and ultimately translocation success will be higher) for animals held inside a pen/aviary for a predetermined period of time before release compared with animals released with no restrictions upon their initial dispersal (Bright & Morris, 1994). However, the relative advantages and disadvantages of frequently used release methods (such as penning) have rarely been scientifically evaluated for reptiles (Hardman & Moro, 2006; Germano & Bishop, 2008). Prior to this study, nine translocations of diurnal geckos (Naultinus spp.) involving hard releases without penning occurred in New Zealand (Table 1). Effort invested in posttranslocation monitoring has often been limited, resulting in very few sightings and failure to confirm population establishment. In seven of these nine translocations, geckos have not been resighted since translocation (Table 1). Given the cryptic nature of green geckos and low detection probabilities (Hare, Hoare & Hitchmough, 2007), it is unclear whether populations failed to establish or were simply not detected in many of these cases. However, in the case of mammal-free Mana Island none of the 48 Wellington green geckos (Naultinus punctatus) translocated there between 1998 and 2005 have been resighted since translocation, despite searches of the release area and surrounds by several experienced herpetologists, including a targeted survey in 2008 involving 90 person-hours of search effort (L. Adams, Department of Conservation, pers. comm.). In contrast, early indications are that the 2009 translocation of jewelled geckos, N. gemmeus, into Orokonui Ecosanctuary has been successful in terms of controlling dispersal and allowing for population establishment (M. Tocher, unpubl. data; Table 1). In this translocation, 36 jewelled geckos were placed in seven separate pens for 1 year before being released (M. Tocher, unpubl. data). Monitoring from 2008 to 2012 indicates that many geckos have stayed in the release area and appear to have formed stable territories (M. Tocher, unpubl. data; C. Knox, unpubl. data). In addition, young have been sighted each year since translocation. These observations provide circumstantial evidence suggesting that penning may be useful for translocations of green geckos, primarily because initial post-release dispersal is restricted (which may assist population establishment). However, the use of a penning strategy in Naultinus gecko transfers has never been thoroughly assessed. In the austral spring of 2012, we evaluated the effects of penning on dispersal of jewelled geckos, through an opportunistic, simultaneous penned versus un-penned release comparison. To our knowledge, our study is the first scientific evaluation of the effects of penning on translocated lizards. We hope it will provide a useful case study to contribute to future metaanalyses regarding the effects of penning on dispersal in herpetofauna translocations. Methods The jewelled gecko (N. gemmeus; McCann 1955) is a moderate-sized (total length up to 160 mm), diurnal, cryptic, arboreal lizard, only found in the southeast of the South Island, New Zealand (Jewell & McQueen, 2007). It is one of nine species of the endemic genus Naultinus and is ranked At Risk, Declining according to the threat Table 1 Translocations of green geckos (Naultinus spp.) in New Zealand prior to 2011 Species Release site (* = mainland) Year Release strategy Post-translocation search effort No. of sightings Reference N. gemmeus Every Scientific Reserve* 1994 Hard, no pen High 0 Shaw 1994 N. manukanus Motuara Island 1997/08 Hard, no pen Low 0 Sherley et al., 2010 N. punctatus Mana Island Hard, no pen High 0 L. Adams, pers. comm. N. manukanus Wakaterepapanui Island 2003 Hard, no pen Moderate 0 Sherley et al., 2010 N. elegans Kereru Grove, Auckland* 2003 Hard, no pen None 0 Sherley et al., 2010 N. elegans Tawharenui Regional Park* Hard, no pen High 1 C. Wedding, pers. comm. N. punctatus Matiu/Somes Island 2007 Hard, no pen Low 0 Sherley et al., 2010 N. north cape Cape Reinga Area* 2008 Hard, no pen None 0 Sherley et al., 2010 N. gemmeus Orokonui Ecosanctuary* 2009 Penned release High 216 M. Tocher, unpubl. data; C. Knox, unpubl. data N. gemmeus Quail Island 2010 Hard, no pen High 2 McClure,

3 Penning reduces dispersal in translocated geckos C. D. Knox and J. M. Monks classification system of the New Zealand Department of Conservation (DOC; Hitchmough et al., 2013). Jewelled geckos are long-lived, viviparous geckos and produce a maximum of two offspring per year (Cree, 1994). The major threats to jewelled geckos are predation by introduced mammals and possibly birds (e.g. magpies, Gymnorhina tibicen and kingfishers, Halcyon sancta vagans), habitat loss or fragmentation (including fires), and illegal collection for the black market (Jewell & McQueen, 2007). This research involved a comparison of dispersal of jewelled geckos immediately following translocation of an un-penned group and the simultaneous removal of a pen surrounding a penned group (which was translocated into the pen 9 10 months prior). Jewelled geckos in both the penned and un-penned group were radio-tracked for 3 weeks from late September to mid-october Penned site: translocation procedure and initial post-release monitoring We undertook an emergency salvage translocation in December 2011 and January 2012, which involved the relocation of 42 jewelled geckos (comprising 21 females (19 gravid adults and two subadults), six males (five adults and one subadult) and 15 juveniles (sex unable to be determined)) from an at risk site on the Otago Peninsula (at risk due to intense illegal collection; Knox, 2010) to Orokonui Ecosanctuary. We photographed the geckos to form an ID library (Knox, Cree & Seddon, 2013) prior to releasing them into a pen made from polythene plastic (c m wide, m long and 0.5 m high). The area of the penned site was m 2, which equated to an area of 27.3 m 2 per adult gecko (n = 24). The penned site was stocked at a density (641 geckos per hectare; all size classes combined) similar to that found at the source site prior to it being decimated by poaching (538 geckos per hectare; Knox, 2010) and we judged habitat suitability to be similar. The purpose of the pen was to restrict initial dispersal in the hope that this would assist geckos to form stable long-term territories at the release site and, ultimately, assist in the establishment of a self-sustaining population. We undertook fourteen photo-resight surveys of 2.5 h duration both within (1.5 h) and around (1 h; up to 30 m away from the boundary) the pen between January and September This entailed six searches during the first 3 months (at 2-week intervals) and eight searches 3 4 weeks apart from months 4 9 following translocation. The aim of these surveys was to gain information on movements and survival, and to check that the pen was successfully confining the geckos within it (hence the search effort outside the pen). Time between surveys was shorter during the first 3 months than the subsequent 6 months because we suspected that jewelled geckos would have been more likely to escape the pen (if they were able to), die or undertake large movements within the pen, during the initial 3 months. We targeted optimal weather conditions for emergence of jewelled geckos during surveys (Duggan, 1991). Unique patterns (stripes and/or diamonds) on the dorsal surface of jewelled geckos enabled accurate identification of individuals (Schneyer, 2001; Knox et al., 2013). Our visual searches covered all habitats potentially containing jewelled geckos within the pen and up to 30 m outside the pen boundary. These habitats primarily consisted of Coprosma taylorae-dominated shrubland (sometimes overlain with Muehlenbeckia spp. vines) and patches of kānuka (Kunzea ericoides). We visually scanned all accessible vegetation for geckos, or movement that might indicate the presence of a gecko. If a gecko was sighted during a search, its location was recorded and it was either captured and photographed (for later identification from the photo database) or identified while basking on the vegetation surface by comparing its appearance to the library of ID photographs from the site. Un-penned site: site selection and translocation procedure We chose a site for the un-penned group with similar habitat composition to, and close to (c. 200 m from), the penned site (described in the previous section). We decided that it was not appropriate to release the un-penned geckos at exactly the same site as the penned geckos, because jewelled geckos are somewhat territorial and show strong site fidelity (C. Knox, pers. obs.). Therefore if both groups were released at the same site the order of release may influence dispersal, with the second arrivals (the un-penned group) potentially being forced out of the release area by the first arrivals (the penned group; as was evidenced in a two-stage translocation of Maud Island frogs, Leiopelma pakeka; Bell, Pledger & Dewhurst, 2004). We rescued 11 individuals [nine adults (six females and three males) and two subadults] from the same site as the penned group in late September 2012 and translocated them to the un-penned release site at Orokonui Ecosanctuary. The area of the un-penned site was 206 m 2 and this equated to an area of 22.9 m 2 per adult gecko (n = 9). Transmitter monitoring Our telemetry study involved simultaneous radio-tracking of 10 adult geckos (nine female; one male) from the penned site (commencing on the day on which the pen was removed) and all nine adult geckos (six female; three male) translocated to the un-penned site (see Table 2 for timeline). The 10 (of 24) adult geckos tracked at the penned site were the first 10 to be resighted at the start of the telemetry study (i.e. the same selection criterion as for the un-penned group was used to avoid any potential bias between groups). The biased sex ratio in each group resulted from finding very few males at the source location and only one male in the Orokonui Ecosanctuary pen at the time of transmitter attachment (note: the original translocated group was biased towards adult females 19:5, excluding subadults and juveniles which made up the remainder of the 42 geckos). We attached g BD2 transmitters and four 0.7 g LB2 20

4 C. D. Knox and J. M. Monks Penning reduces dispersal in translocated geckos Table 2 Timeline and design of our study investigating translocation of jewelled geckos, Naultinus gemmeus, with either a pen to limit initial dispersal ( penned group ) or with no barrier to dispersal ( un-penned group ) Timing Penned group Un-penned group December 2011 January 2012 Rescue of 42 geckos (24 adults; 18 juveniles/subadults) from Otago Peninsula and translocation into a pen at Orokonui Ecosanctuary September 2012 Removal of pen Rescue of 11 geckos (nine adults; two juveniles/subadults) from the same site on Otago Peninsula and translocation to an un-penned site at Orokonui Ecosanctuary 200 m from the penned site September October Radio-tracking of 10 geckos, starting the day the pen Radio-tracking of nine geckos, starting the same day 2012 was removed December 2013 Follow-up survey of reproductive status of females at both sites transmitters (Holohil Systems, Carp, ON, Canada) to 19 jewelled geckos on 28 September 2012 to monitor their movements for c. 3 weeks (the batteries in these transmitters typically last 3 5 weeks). Transmitters weighed 7.5% of body weight of geckos and were attached using an external backpack harness (Salmon, 2002; Hoare et al., 2007) using a hypoallergenic, self-adhesive fabric strip (22 cm 3 mm) coloured green with a xylene-free permanent marker for camouflage. We monitored movements of the 19 geckos for the 3 weeks following transmitter attachment. We recorded locations and movements (distance and bearing, using a compass, marker peg and tape measure accurate to c. 0.1 m) once or twice daily. At the end of the 3-week period, we caught all geckos (except for one) and removed the transmitters. We were unable to find and remove the transmitter from one gecko because the transmitter it was wearing malfunctioned; however, previous research demonstrates that the harness material stretches sufficiently during heavy rain for geckos to climb out of the harness and be free of the transmitter (J. Monks, unpubl. data). We evaluated effects of release group (penned or un-penned), sex and their interaction (as fixed factors) on dispersal using a linear mixedeffects model. Log-transformed distance between fixes was included as the dependent variable and individual as a random effect. We also investigated differences in (straightline) distance between release point and location of each gecko at the end of the telemetry study using a linear model with log-transformed distance as the dependent variable and release group as a fixed factor. We constructed our models using the nlme and stats packages (respectively) in the statistical programme R. We checked that our data satisfied the assumptions of the statistical tests used. Summary statistics are presented as means plus or minus the standard error unless otherwise stated. Additional observations At the beginning of the austral summer following this study (i.e. in December 2013), we conducted a brief visual survey (three person-hours split across 2 days) at each release site to evaluated reproductive status of any adult female geckos seen (Table 2). Females seen were captured and gently palpated (for follicles and embryos) to assess reproductive status. Results Penned site: photo-resight monitoring (January September 2012) Our visual monitoring provided no evidence of translocated jewelled geckos being able to exit the pen while it was in place [we spent one hour per survey (comprising 40% of survey time) surveying the immediate area up to 30 m outside of the pen]. We resighted c. 80% (33 of 42) geckos and 92% (22 of 24) of the mature adult geckos at least once inside the pen following translocation. Although small sample sizes did not allow for a thorough statistical analysis of movement data over this period, some of the geckos appeared to roam widely within the pen during the first 3 months after translocation (sum of recorded movements per individual was up to m, n = 9), before appearing to establish stable territories between months four and nine (up to 18.5 m, n = 14). Transmitter monitoring (September October 2012) We detected differences in daily movements over the 3-week radio-tracking period related to treatment (penning; t 15 = 2.285, P = 0.037). Mean daily movements over the 3-week period were 1.61 m (±0.21 m) for the un-penned group and 1.06 m (±0.16 m) for the penned group. At the end of the 3-week monitoring period, the penned geckos were closer to their release points (mean distance = 4.99 ± 1.47 m) than the un-penned geckos (mean distance = ± 4.46 m; t 17 = 2.640, P = 0.017; Fig. 1). The largest total distance covered over the 3 weeks for a male was 80.6 m (un-penned) and 68.4 m for a female (penned); whereas the minimum total movement was 4.3 m (female, penned; Table 3). The largest daily movement was 23.3 m for a male (un-penned) and 21.7 m for a female 21

5 Penning reduces dispersal in translocated geckos C. D. Knox and J. M. Monks a a b b Figure 1 Movements of jewelled geckos (Naultinus gemmeus) recorded using BD2 transmitters over 3 weeks in (a) a penned group immediately after removal of the pen (indicated by a dotted line) in which they had been held for 9 10 months (n = 10) and (b) an un-penned group immediately following translocation (n = 9). Individual geckos are represented by symbols with unique shape and colour combinations (e.g. grey triangle). Small symbols indicate start points and large symbols indicate end points. The line between these points is the gecko s movements (of 0.1 m) over the 3-week radiotracking period. (penned; Table 3). Despite detecting large differences in movements among individuals in both penned and un-penned treatments, we did not detect either sex-specific differences in movements (t 15 = 1.009, P = 0.329) or an interaction between sex and the penning treatment (t 15 = 0.282, P = 0.782). However, small sample sizes (particularly for males; n = 4) restricted statistical power. None of the penned geckos that we radio-tracked moved outside of their release area despite the pen being removed at the commencement of monitoring and suitable habitat being available outside the pen area (Fig 1a). However, we saw one non-tracked male 3.5 m outside of the pen following its removal. A further eight non-tracked adults were sighted within the pen area during transmitter monitoring meaning that at least 19 of the original 24 adults were still Figure 2 The area occupied by radio-tracked jewelled geckos (Naultinus gemmeus) at and 3 weeks after either (a) removal of a pen in which they had been held for c. 9 months (n = 10) and (b) an un-penned translocation (n = 9). Open circles and black triangles indicate the geckos positions at the beginning and end of the monitoring period, respectively. The solid and dotted lines drawn around start and end positions, respectively, illustrate the change in area occupied. present in the release area 9 10 months following translocation. The fate of the other five geckos is uncertain; however, it is possible that some or all of these five geckos were in the pen area but simply not detected, as the species is highly cryptic and vegetation density and height made visual surveying problematic in some small areas within the pen (about 15% of the pen area). Area of occupancy of penned geckos remained similar during the 3-week period following removal of the pen (Fig. 1a). In contrast, some of the un-penned geckos moved distances of up to 40 m to the east, and 30 m to the southwest and north-east, of their release area (Fig. 1b), effectively increasing the area they collectively occupied 4.4-fold (from 206 m 2 to 897 m 2 ; Fig. 2). Upon initial release (into the pen) the penned geckos were at a density of 27.3 m 2 / adult gecko (n = 24) and at the end of the radio-tracking (c. 10 months later) these geckos appeared to cover a similar area (i.e. only one untracked adult gecko was sighted outside the pen area by 3.5 m, five adults were unsighted and 22

6 C. D. Knox and J. M. Monks Penning reduces dispersal in translocated geckos Table 3 Movements and behaviour of 19 jewelled geckos (Naultinus gemmeus) radio-tracked over a 3-week period following translocation. Nine geckos tracked were un-penned (no barrier to dispersal) and the other 10 geckos were penned (in a temporary enclosure within the release site for 9 10 months prior to its removal at the start of the telemetry monitoring period) Individual Sex Fixes Total moved (m) Final distance from release (m) Max. daily movement (m) Mean perch height (m) Un-penned group 1 F M F F M F F F F Mean Penned group 1 F F F F F F F M F F Mean Emergence (%) the remaining 18 adults were sighted inside the pen area). In contrast, at release the un-penned geckos were at a density of 22.9 m 2 /adult gecko (n = 9); but by the end of the 3-week radio-tracking density had decreased to 99.7 m 2 /adult gecko due to dispersal (Fig. 1b; Fig. 2b). Additional observations During our search of both sites in December 2013, 14 months after the telemetry study, four adult female geckos were found at the site of the former pen and two adult female geckos were found at the former un-penned site. All female geckos at the penned release site were gravid, but neither of the two females at the un-penned site was gravid. Discussion It remains unclear whether a colony of jewelled geckos will form at the un-penned site, but even if a colony does form, some individuals may be lost to the establishing colony (i.e. those that continue to disperse away from the other geckos). This may result in reduced founder size and consequences of loss of genetic diversity, reduced population growth rates and increased extinction risk (Frankham, 2005; O Grady et al., 2006; Miller et al., 2009). In light of this, and our observation that neither of the adult female geckos resighted at the un-penned site the summer following this research were gravid (which is highly unusual for female jewelled geckos; C. Knox, unpubl. data) implying that no males remained in the release area or were available for mating, we suspect that the likelihood and/or speed of population growth and establishment may be hampered when a pen is not used for Naultinus gecko translocations. A secondary advantage of penning is that it assists monitoring of the translocated population during the initial stages of population establishment and can provide invaluable information on poorly known taxa (which is the case for many New Zealand lizards; Hare et al., 2007; Hitchmough et al., 2013). Little is published on the movement patterns of either natural or translocated populations of Naultinus geckos, but available information suggests substantial variability among species and populations. In our study, mean daily movements of jewelled geckos were 1.61 m for the un-penned group and 1.05 m for the penned group. Similarly, Hare et al. (2007) found that a natural population of Marlborough green geckos, N. manukanus, on Stephens Island moved a mean distance of only 0.6 m per day. In contrast, mean daily movements of ten female jewelled geckos hard-released without a pen on Quail Island, Canterbury in January 2011 were m (McClure, 2011). The wide variation in movements may indicate that Naultinus geckos can behave unpredictably following translocation and are capable of dispersing large distances. Animal movements and survival following translocation may vary greatly from site to site depending on a range of factors, including the species, the history of the individuals (e.g. captive or wild), the species response to stress during and immediately after translocation (Jamieson & Wilson, 23

7 Penning reduces dispersal in translocated geckos C. D. Knox and J. M. Monks 2003), the release technique (e.g. Bright & Morris, 1994), the size of the pen or aviary if one is used (e.g. an enclosure that is too small may result in stress to the animals), habitat quality including the availability of food and other resources at the receptor site (Armstrong et al., 2002), founder size, the presence or absence of conspecifics as well as various predators and competitors (Bramley & Veltman, 1998), season (Eastridge & Clark, 2001; this may be particularly important for ectothermic animals), weather conditions and the unique challenges the animals may face at any given release site. Most published research on the effects of different translocation strategies concerns either mammals or birds. Bright & Morris (1994) compared reintroductions of the dormouse (Muscardinus avellanarius) using experimental translocations. Penned dormice continued to nest at their release point and utilized supplementary food, whereas un-penned dormice often dispersed widely and ignored food provided (Bright & Morris, 1994). In contrast, Clarke et al. (2002) found no difference in dispersal between hardreleased and soft-released black-eared miners (Manorina melanotis) and Hardman & Moro (2006) found no difference in establishment or survival of penned versus un-penned hare-wallabys (Lagorchestes sp.) when both groups received supplementary feeding. These studies emphasize how different release strategies seem to be appropriate for different species. Penning may be beneficial for some species, but not others. Likewise, some species may benefit from supplementary food or nest boxes/burrows, while others may derive no benefit from soft-release measures. Little research has been done on penning and/or softrelease translocations of herpetofauna; however, there are a few cases that show that penning can increase site fidelity and translocation success for reptiles. For example, Tuberville et al. (2005) tested the effects of penning on site fidelity and activity area size in the gopher tortoise (Gopherus polyphemus). In their study, 38 adults and subadults were assigned to one of three penning treatments (9 months, 12 months and no penning) and then radiotracked for 2 years. Penning significantly increased site fidelity and reduced dispersal, suggesting that penning would improve the likelihood of establishing self-sustaining tortoise populations (Tuberville et al., 2005). Similarly, forced aestivation soft releases may succeed in reducing dispersal by forcing spur-thighed tortoises, Testudo graeca, to spend time at the release site as evidenced by similar activity range sizes and movement path tortuosity in translocated and resident tortoises (Attum et al., 2011). It is important that the relative merits and disadvantages of different release strategies, including penning, on herpetofauna are studied further because translocations of these animals are becoming increasingly frequent (Germano & Bishop, 2008; Sherley, Stringer & Parrish, 2010). Although a penning strategy has previously been used in at least two lizard translocations (M. Tocher, unpubl. data; Treglia, 2010) and headstarting (pre-release training) has been used in reintroductions of captive lizards (e.g. Alberts, 2007), we are not aware of other research to date evaluating the appropriateness of penning for wild-to-wild translocation of lizards by comparison with an un-penned group. Given that our study of jewelled geckos corroborates findings about the utility of penning in limiting dispersal and assisting establishment of tortoise populations (Tuberville et al., 2005), we suspect that penning may be a successful technique for translocating many herpetofauna species. However, we acknowledge that sample sizes were small in our study and we therefore recommend further research to more thoroughly assess the effects of penning on posttranslocation dispersal of jewelled geckos and other lizards. We believe that the potential advantages of penning (e.g. avoiding the loss of founders, which disperse to far from the release site and increased ease of monitoring) outweigh the disadvantages (e.g. the cost of materials and time spent constructing the pen). This may be particularly true for species such as green geckos, where founder populations can easily be enclosed in a sufficient area of habitat with inexpensive polythene sheeting. We recommend that penning should be considered for herpetofaunal translocations, particularly in situations where dispersal is not limited by natural barriers. Acknowledgements We thank the staff at Orokonui Ecosanctuary for permission to undertake translocations and associated research, access to facilities, provision of materials and help with construction of the pen and support and assistance during the entire study. We wish to acknowledge Mandy Tocher, Bernard Goetz, Tony Jewell and Mike Fay for designing the pens used in the first jewelled gecko translocation to Orokonui Ecosanctuary; they paved the foundations for this research. Thanks to Lynn Adams, Christine McClure and Chris Wedding for providing personal communications, Adrian Monks for graphical assistance and Doug Armstrong and an anonymous reviewer for improving the paper. Thanks also to the volunteers who helped with monitoring, construction of the pen and various other aspects of the study. We thank the Department of Conservation and Setpoint Ltd. for funding. Our study was approved by the Department of Conservation (DOC) Animal Ethics Committee (permit number AEC 246) and funded through DOC Science Investigation References Alberts, A.C. (2007). Behavioral considerations of headstarting as a conservation strategy for endangered rock iguanas. Appl. Anim. Behav. Sci. 102, Armstrong, D.P., Davidson, R.S., Dimond, W.J., Perrott, J.K., Castro, I., Ewen, J.G., Griffiths, R. & Taylor, J. (2002). Population dynamics of reintroduced forest birds on New Zealand islands. J. Biogeogr. 29, Attum, O., Otoum, M., Amr, Z. & Tietjen, B. (2011). Movement patterns and habitat use of soft-released translocated spur-thighed tortoises, Testudo graeca. Eur. J. Wildlife Res. 57,

8 C. D. Knox and J. M. Monks Penning reduces dispersal in translocated geckos Bell, B.D., Pledger, S. & Dewhurst, P.L. (2004). The fate of a population of the endemic frog Leiopelma pakeka (Anura: Leiopelmatidae) translocated to restored habitat on Maud Island, New Zealand. New Zeal. J. Zool. 31, Bramley, G.N. & Veltman, C.J. (1998). Failure of translocated, captive-bred North Island weka Gallirallus australis greyi to establish a new population. Bird Conserv. Int. 8, Bright, P.W. & Morris, P.A. (1994). Animal translocation for conservation: performance of dormice in relation to release methods, origin and season. J. Appl. Ecol. 31, Clarke, R.H., Boulton, R.L. & Clarke, M.F. (2002). Translocation of the socially complex black-eared miner Manorina melanotis: a trial using hard and soft release techniques. Pac. Conserv. Biol. 8, Cree, A. (1994). Low annual reproductive output in female reptiles from New Zealand. New Zeal. J. Zool. 21, Dodd, C.K. & Seigel, R.A. (1991). Relocation, repatriation, and translocation of amphibians and reptiles: are they conservation strategies that work? Herpetologica 47, Duggan, L. (1991). Emergence behaviour of Naultinus gemmeus, the jewelled gecko, on Otago Peninsula. Wildlife Management Report 14. University of Otago, Dunedin, New Zealand. Eastridge, R. & Clark, J.D. (2001). Evaluation of 2 penning techniques to reintroduce black bears. Wildlife Soc. B. 29, Ewen, J.G., Armstrong, D.P., Parker, K.A. & Seddon, P.J. (2012). Reintroduction biology: integrating science and management. Oxford: Wiley-Blackwell. Frankham, R. (2005). Genetics and extinction. Biol. Conserv. 126, Germano, J.M. & Bishop, P.J. (2008). Suitability of amphibians and reptiles for translocation. Conserv. Biol. 23, Griffith, B., Scott, J.M., Carpenter, J.W. & Reed, C. (1989). Translocation as a species conservation tool: status and strategy. Science 245, Hardman, B. & Moro, D. (2006). Optimising reintroduction success by delayed dispersal: is the release protocol important for hare-wallabies? Biol. Conserv. 128, Hare, K.M., Hoare, J.M. & Hitchmough, R.A. (2007). Investigating natural population dynamics of Naultinus manukanus to inform conservation management of New Zealand s cryptic diurnal geckos. J. Herpetol. 41, Hitchmough, R., Anderson, P., Barr, B., Monks, J., Lettink, M., Reardon, J., Tocher, M. & Whitaker, T. (2013). Conservation status of New Zealand reptiles, New Zealand threat classification series 2. Wellington: Department of Conservation. Hoare, J.M., Pledger, S., Nelson, N.J. & Daugherty, C.H. (2007). Avoiding aliens: behavioural plasticity in habitat use may enable large, nocturnal geckos to survive Pacific rat invasions. Biol. Conserv. 136, Jamieson, I.G. & Wilson, G.C. (2003). Immediate and longterm effects of translocations on breeding success in takahe Porphyrio hochstetteri. Bird Conserv. Int. 13, Jewell, T. & McQueen, S. (2007). Habitat characteristics of jewelled gecko (Naultinus gemmeus) sites in dry parts of Otago. DOC Research and Development Series 286, Department of Conservation, Wellington, New Zealand. Knox, C.D. (2010). Habitat requirements of the jewelled gecko (Naultinus gemmeus): effects of grazing, predation and habitat fragmentation. MSc thesis, University of Otago, Dunedin, New Zealand. Knox, C.D., Cree, A. & Seddon, P.J. (2013). Accurate identification of individual geckos (Naultinus gemmeus) through dorsal pattern differentiation. New Zeal. J. Ecol. 37, Letty, J., Marchandeau, S. & Aubineau, J. (2007). Problems encountered by individuals in animal translocations: lessons from field studies. Ecoscience 14, McClure, C. (2011). Testing translocation, detection and live-trapping methods for New Zealand lizards. BSc (Hons) thesis, Lincoln University, Christchurch, New Zealand. Miller, K.A., Nelson, N.J., Smith, H.G. & Moore, J.A. (2009). How do reproductive skew and founder group size affect genetic diversity in reintroduced populations? Mol. Ecol. 18, O Grady, J.J., Brook, B.W., Reed, D.H., Ballou, J.D., Tonkyn, D.W. & Frankham, R. (2006). Realistic levels of inbreeding depression strongly affect extinction risk in wild populations. Biol. Conserv. 133, Salmon, N.M. (2002). Telemetric studies of the geckos Hoplodactylus maculatus and Naultinus gemmeus. MSc thesis, University of Otago, Dunedin, New Zealand. Schneyer, N. (2001). Effects of avian predation and habitat degradation on the population dynamics of the jewelled gecko (Naultinus gemmeus) from the Every Reserve, Otago Peninsula, New Zealand. MSc thesis, University of Otago, Dunedin, New Zealand. Seddon, P.J., Armstrong, D. & Maloney, R.F. (2007). Developing the science of reintroduction biology. Conserv. Biol. 21, Seddon, P.J., Strauss, W.M. & Innes, J. (2012). Animal translocations: what are they and why do we do them? In Reintroduction biology: integrating science and management: Ewen, J.G., Armstrong, D.P., Parker, K.A. & Seddon, P.J. (Eds). Oxford: Wiley and Blackwell. Shaw, T. (1994). Population size, distribution, home range and translocation of the jewelled gecko. Wildlife Management Report 56, University of Otago, Dunedin, New Zealand. 25

9 Penning reduces dispersal in translocated geckos C. D. Knox and J. M. Monks Sherley, G.H., Stringer, I.A.N. & Parrish, G.R. (2010). Summary of native bat, reptile, amphibian and terrestrial invertebrate translocations in New Zealand. Wellington: Department of Conservation, Science for Conservation 303. Treglia, M.L. (2010). A translocated population of the St. Croix ground lizard: analyzing its detection probability and investigating its impacts on the local prey base. MSc thesis, Texas A&M University, College Station. Tuberville, T.D., Clark, E.E., Buhlmann, K.A. & Gibbons, J.W. (2005). Translocation as a conservation tool: site fidelity and movement of repatriated gopher tortoises (Gopherus polyphemus). Anim. Conserv. 8, Wanless, R.M., Cunningham, J., Hockey, P.A.R., Wanless, J., White, R.W. & Wiseman, R. (2002). The success of a soft-release reintroduction of the flightless Aldabra rail (Dryolimnas cuvieri aldabranus) on Aldabra Atoll, Seychelles. Biol. Conserv. 107,