Age and sex specific timing, frequency, and spatial distribution of horseshoe crab spawning in Delaware Bay:Insights from a large-scale radio telemetry array

To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent （〉100 km）, we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and archival tags on adult horseshoe crabs prior to their spawning season. We tagged and released 160 females and 60 males in 2004 and 217 females in 2005. The array covered approximately 140 km of shoreline. Recapture rates were 〉70% with multi-year recaptures. We categorized adult age by carapace wear. Older females tended to spawn earlier in the season and more frequently than young females, but those tendencies were more apparent in 2004 when spawning overall occurred earlier than in 2005 when spawning was delayed possibly due to decreased water temperatures. Timing of initial spawning within a year was correlated with water temperature. After adjusting for day of first spring tide, the day of In＇st spawning was 4 days earlier for every 1 degree （℃） rise in mean daily water temperature in May. Seventy nine % of spawning occurred during nighttime high tides. Fifty five % of spawning occurred within 3 d of a spring tide, which was slightly higher than the 47% expected if spawning was uniformly distributed regardless of tidal cycle. Within the same spawning season, males and females were observed spawning or intertidally resting at more than one beach separated by 〉5 kin. Between years, most （77%） did not return to spawn at the same beach. Probability of stranding was strongly age dependent for males and females with older adults experiencing higher stranding rates. Horseshoe crabs staging in the shallow waters east of the channel spawned exclusively along the eastern （N J） shoreline, but those staging west of the channel spawned throughout the bay. Overall, several insights emerged from the use of radio telemetry, which advances our understanding of horseshoe crab ecology and will be useful in conserving the Delaware Bay horseshoe crab population and habitats

Home Range Size and Overlap of the Small Nocturnal Schlegel’s Japanese Gecko (Gekko japonicus), Introduced into a City Park in Korea

Studying the home range of an organism is important in understanding its ecology. Due to being cryptic, few studies have been conducted on the home range studies of small, nocturnal geckos. We conducted radio-tracking surveys for 23 individuals to estimate the home range size and home range overlap of the Schlegel’s Japanese gecko(Gekko japonicus) previously introduced into a suburban city park. Individuals were commonly found in artificial structures(buildings and accessory structures) and on nearby natural trees. Daily moved distance was positively correlated with home range size. Minimum convex polygon(MCP) home range was 97.8 m^2 for females and 99.5 m^2 for males, on average. Gekko japonicus moved farther daily distances and used wider MCP and Kernel 95 home ranges in breeding season compared to non-breeding season, while the size of Kernel 50 home range did not differ between seasons. Both daily moved distance and home range size were not significantly different between sexes. In the breeding season, MCP and Kernel 50 home ranges of each gecko overlapped with 32.4% and 13.8% of remaining geckos, respectively. Our results not only show that 1) G. japonicus uses both artificial structures and adjacent natural trees as microhabitat, but also suggest that 2) G. japonicus is non-territorial, but has a core habitat that is shared with few other individuals, and 3) the reproductive system of G. japonicus is polygamous.

Review of research methodologies for tigers:Telemetry

Over the past half century,wildlife research has relied on technological advances to gain additional insight into the secretive lives of animals.This revolution started in the 1960s with the development of radio telemetry and continues today with the use of Global Positioning System(GPS)-based research techniques.In the present paper we review the history of radio telemetry from its origins with grizzly bears in Yellowstone to its early applications in tiger research and conservation in Asia.We address the different types of data that are available using radio telemetry as opposed to using other research techniques,such as behavioral observations,camera trapping,DNA analysis and scat analysis.In the late 1990s,the rapid development of GPS collar technology revolutionized wildlife research.This new technology has enabled researchers to dramatically improve their ability to gather data on animal movements and ecology.Despite the ecological and conservation benefits of radio telemetry,there have been few telemetry studies of tigers in the wild,and most have been on the Bengal or Amur subspecies.We close with an assessment of the current tiger conservation efforts using GPS technology and discuss how this new information can help to preserve tigers for future generations.