Person: Kays, Roland
Kays, Roland
Loading...
Email Address
Affiliation
ORCID
Birth Date
Job Title
Last Name
Kays
First Name
Roland
Creator of
Editor of
Reviewer of
Copyright Holder of
Data Contributor of
Funder of
Translator of
Other Contributor of
5 results
Search Results
Now showing 1 - 5 of 5
- Data packageData from: The effect of feeding time on dispersal of Virola seeds by toucans determined from GPS tracking and accelerometers(2016-01-12) Kays, Roland; Jansen, Patrick A.; Knecht, Elise M.H.; Vohwinkel, Reinhard; Wikelski, MartinSeed dispersal is critical to understanding forest dynamics but is hard to study because tracking seeds is difficult. Even for the best-studied dispersal system of the Neotropics, Virola nobilis, the dispersal kernel remains unknown. We combined high-resolution GPS/3D-acceleration bird tracking, seed-retention experiments, and field observations to quantify dispersal of V. nobilis by their principal dispersers, Ramphastos toucans. We inferred feeding events from movement data, and then estimated spatiotemporally explicit seed-dispersal kernels. Wild toucans moved an average of 1.8 km d^-1 with two distinct activity peaks. Seed retention time in captive toucans averaged 25.5 min (range 4-98 min). Estimated seed dispersal distance averaged 144 +/- 147 m, with a 56% likelihood of dispersal >100 m, two times further than the behaviour-naive estimate from the same data. Dispersal was furthest for seeds ingested in the morning, and increased with seed retention time, but only up to 60 min after feeding. Our study supports the long-standing hypothesis that toucans are excellent dispersers of Virola seeds. To maximize seed dispersal distances trees should ripen fruit in the morning when birds move the most, and produce fruits with gut-processing times around 60 min. Our study demonstrates how new tracking technology can yield nuanced seed dispersal kernels for animals that cannot be directly observed.
- Data packageData from: Ámbito de hogar y actividad circadiana del ocelote (Leopardus pardalis) en la Isla de Barro Colorado, Panamá(2020-07-03) Moreno, Ricardo; Mares, Rafael; Aliaga-Rossel, Enzo; Kays, RolandBecause ocelots (Leopardus pardalis) are elusive species in the wild, little is known of them. This study determines the home range and circadian activity of this feline in the Barro Colorado Island (BCI), Panama. This island has a wet tropical rainforest. Using wooden box traps and Tomahawk traps, between July 2001 and May 2004 15 ocelots were captured, and three other ocelots in 2009. Once captured, they were sedated and VHF collars were fitted, for the ones captured in 2009 we fitted GPS collars. Camera-traps were used to get additional information from individuals without collars and a more reliable data interpretation. The average home range of ocelots, obtained by radio-telemetry was 3.48 km2 (DE: 3.17) for males and 1.48 km2 (DE: 0.65) for females, although an adult male used an area of 9 km2. Males traveled on average 1.15 km per day and females 0.7 km. Through telemetry and camera traps, we found that ocelots were primarily nocturnal (Night = 63.2%; Day = 36.8%). Our results are similar to other studies; however, they suggest that BCI ocelots have smaller home ranges due to the high availability of food and also by the high density of females within the home ranges of males.
- Data packageData from: Large-range movements of neotropical orchid bees observed via radio telemetry(2020-07-03) Wikelski, Martin; Moxley, Jerry; Eaton-Mordas, Alexander; López-Uribe, Margarita M.; Holland, Richard A.; Moskowitz, David; Roubik, David W.; Kays, RolandNeotropical orchid bees (Euglossini) are often cited as classic examples of trapline-foragers with potentially extensive foraging ranges. If long-distance movements are habitual, rare plants in widely scattered locations may benefit from euglossine pollination services. Here we report the first successful use of micro radio telemetry to track the movement of an insect pollinator in a complex and forested environment. Our results indicate that individual male orchid bees (Exaerete frontalis) habitually use large rainforest areas (at least 42–115 ha) on a daily basis. Aerial telemetry located individuals up to 5 km away from their core areas, and bees were often stationary, for variable periods, between flights to successive localities. These data suggest a higher degree of site fidelity than what may be expected in a free living male bee, and has implications for our understanding of biological activity patterns and the evolution of forest pollinators.
- Data packageData from: Stink or swim: techniques to meet the challenges for the study and conservation of small critters that hide, swim or climb and may otherwise make themselves unpleasant.(2015-05-25) Kays, Roland; Hirsch, Ben T.The study of musteloids requires different perspectives and techniques than those needed for most mammals. Musteloids are generally small yet travel long distances and many live or forage underground or under water, limiting the use of telemetry and direct observation. Some are arboreal and nocturnal, facilitating telemetry but limiting observation, trapping, and many non-invasive techniques. Large sexual size dimorphism arguably doubles sample sizes for many research questions. Many musteloids defend themselves by expelling noxious chemicals. This obscure group does not attract funding, even when endangered, further reducing rate of knowledge gain. Nonetheless, passive and active radio frequency identification tags, magnetic-inductance tracking, accelerometers, mini-biologgers and some GPS tags are tiny enough for use with small musteloids. Environmental DNA can document presence of animals rarely seen. These technologies, coupled with creative research design that is well-grounded on the scientific method, form a multi-dimensional approach for advancing our understanding of these charismatic minifauna.
- Data packageData from: Thieving rodents as substitute dispersers of megafaunal seeds(2012-06-27) Jansen, Patrick A.; Hirsch, Ben T.; Emsens, Willem-Jan; Zamora-Gutierrez, Veronica; Wikelski, Martin; Kays, RolandThe Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other’s buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees.