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incision, and placed one drop of Bactine (Bayer Co., Pittsburgh,Pennsylvania, USA) on the wound to sterilize the incision andpromote healing. Frogs recovered from surgery for 6 hours beforerelease, and we assessed tag retention and the condition ofthe wound after the frog recovered.We conducted a two-week laboratory trial to determine the bestposition for PIT tag placement in small ranids. Three positions(scapula insertion, pubis insertion, ilium insertion) were tested inrecently metamorphosed R. pipiens (N = 20 for each position).For scapula insertion, a longitudinal incision on the dorsum wasmade above the scapula ~ 3 mm posterior to the eye and ~ 2 mmmedial to the tympanum. For pubis insertion, a lateral incisionwas made ~ 2 mm anterior to the posterior end of the urostyle. Forilium insertion, a longitudinal incision was made ~ 1 mm anteriorto the anterior end of the ilium and centered on the dorsum. Thefrogs used in the experiment were 34 ± 1 mm (mean ± SE; range31–38) SVL and weighed 4.0 ± 0.3 g (range 2.8–6.1). Frogs werechecked twice daily for tag retention and healing of the surgicalwound.Based on the results of the retention study, we PIT tagged(scapula insertion) 50 adult R. sylvatica (26 males, 24 females; 46± 1 mm SVL, range 41–55 mm; 14.5 ± 0.5 g, range 10.1–24.9 g)and 52 recently metamorphosed R. pipiens (37 ± 1 mm SVL, range31–48; 4.5 ± 0.2 g, range 1.0–8.7 g) in August 2006. Tagged frogswere placed into uninhabited 3.8 × 3.8 m (14.4 m 2 ) terrestrial enclosuresconstructed 15 months prior to data collection in an unharvestedforest (unharvested), a forest partially harvested to 50%crown closure (partial), and a 3-year old clearcut with coarse woodydebris removed (removed) on the Dwight B. Demeritt andPenobscot Experimental Forests (see Patrick et al. 2006 for a descriptionof the sites). Enclosure walls were 1.2 m tall galvanizedsteel hardware cloth (3.2 mm square mesh; TWP Inc., Berkeley,California, USA) supported with wooden garden stakes. Enclosurewalls were buried 20–30 cm in the ground and bent 10 cm atthe top toward the inside of the pen to prevent escape of animals.We stocked terrestrial enclosures with R. pipiens metamorphsand R. sylvatica adults. Rana pipiens metamorphs were stocked tothree enclosures: one enclosure in the removed treatment at a densityof 12 per enclosure (0.83 m -2 ), one in the removed treatmentat a density of 20 per enclosure (1.39 m -2 ), and one in the unharvestedtreatment at a density of 20 per enclosure (1.39 m -2 ). Wewere unable to capture enough R. pipiens metamorphs at our studysites to replicate each density and treatment combination. For R.sylvatica adults, we stocked each of 10 enclosures at a density offive per enclosure (0.35 m -2 ): five enclosures in the partial treatmentand five in the unharvested treatment. We located R. pipiensmetamorphs every three days during 23 August – 7 September2006 and once weekly thereafter through 11 October (the end ofthe growing season in central Maine). We located R. sylvatica adultsonce weekly from 26 August to 27 September 2006. We removeddead frogs and did not include them in subsequent detection probabilitycalculations.Lastly, we captured (drift fences and by hand) 139 adult R.sylvatica (61 females, 78 males) returning to breed at a single, ~80-m 2 vernal pool on the University of Maine’s Dwight B. DemerittExperimental Forest in April 2007. Each frog was PIT tagged(scapula insertion), and held in captivity for < 9 h prior to releaseat ~ 1 h before sunset. Nightly during 22 April – 2 May we locatedpairs in amplexus with a spotlight and by scanning the surface ofthe water with the PIT-pack. We attempted to identify both membersof each located pair with the PIT-pack without disturbing thefrogs. We relocated the pair visually and with the PIT-pack untilthe female oviposited. Each morning we counted the number offresh egg masses in the pond. We conducted all statistical analysesin SAS (SAS Institute, Cary, North Carolina, USA) with α =0.05.Results and Discussion.—Our mean detection probability was0.65 ± 0.14 (± 95% confidence interval), and we detected 100 ±0% of the tags at 13 cm and 33 ± 7% of PIT tags at 43 cm in thesoil (Fig. 2). The informed observer (i.e., who knew the locationof the tags) detected a higher proportion of tags in a single pass(0.76) than the blind observer (0.61 ± 0.03; range 0.57–0.67) didin three passes. This higher success in detecting tags is probablydue to increased effort in an area known to have a tag versus thesystematic pattern employed by the blind observer. Subtle changesin antenna orientation associated with concentrated effort in onearea can change detection success without a change in detectionrange. The antenna is most effective at detecting a tag if the tag isperpendicular to the face of the antennae (Cucherousset et al. 2005).No frogs died during the two-week tag retention experiment.Tag retention after two weeks was highest with the scapula insertiontechnique; all R. pipiens retained their tags. Retention alsowas high with ilium insertion (90%), but retention with pubis insertionwas poor (55%). All tag loss occurred before the incisionhealed, generally in < 6 days during these laboratory trials. Thescapula and ilium insertion techniques will probably result in hightag retention rates in other similar sized frogs, although retentionrates are important to quantify for any field study.The proportion of recently metamorphosed R. pipiens detectedwith a PIT-pack was not affected by harvesting treatment or density,and the proportion detected in the three terrestrial enclosuresremained at 1.00 throughout the study (Fig. 3). The proportion ofadult R. sylvatica detected remained high (> 0.90) until the firsttime the minimum daily temperature (MDT) was < 0°C, but declinedover subsequent surveys. Because the proportion detectedFIG. 2. Mean (± 95% confidence interval) proportion of PIT tags detectedper depth in the soil using a PIT-pack in two 16 m 2 areas. Eachdepth had six tags available for detection and means were calculated fromall four passes with the PIT-pack. All depths 50 cm were lumped.176 Herpetological Review 39(2), 2008