Christopher Vaughan

Spatial ecology and conservation of two sloth species in a cacao landscape in limón, Costa Rica

The spatial ecology of sloths was studied in an agricultural landscape in Limón Province, Costa Rica. Two sloth species, the three-toed sloth (Bradypus variegatus) and the two-toed sloth (Choloepus hoffmanni), actively used and traveled through a cacao agroforest and its contiguous living fence rows and riparian forests. This agroecosystem was embedded in an agricultural landscape dominated by banana and pineapple plantations and pastures with dispersed trees. The two-toed sloth (C. hoffmanni) was found in 101 tree species and used 34 for food; the three-toed sloth (B. variegatus) was found in 71 tree species and used 15 for food. Choice of preferred species differed between the two sloth species. Trees commonly used by sloths for food and/or refuge in the cacao agroforest included Erythrina poeppigiana, Cecropia obtusifolia, Leucaena leucocephala; in the living fence rows, Cordia alliodora, Erythrina poeppigiana, Ocotea sinuata and Trophis racemosa; in the riparian forests, Coussapoa villosa, Cecropia obtusifolia, Hura crepitans, Pterocarpus officinalis and Spondias mombin; and in the pastures with dispersed trees, Cordia alliodora, Coussapoa villosa, Erythrina poeppigiana, Ocotea sinuata and Hura crepitans. This study demonstrates the importance of the cacao agroforest as well as arboreal elements in other land uses in providing resources for sloth conservation in a larger agricultural landscape.

Response of a Scarlet Macaw Ara macao population to conservation practices in Costa Rica

Summary The Central Pacific Conservation Area contains one of Costa Rica’s two viable, but threatened Scarlet Macaw Ara macao populations. For 14 years (1990–2003), we monitored the size of this population. Non-linear models fitted to 1990–1994 observations revealed seasonal and longterm changes in population size. The peak of annual population size occurred in August, with a cyclic range of about 90 birds between the lowest and highest points of the annual cycle. The best model also revealed a decline in population size of approximately eight birds counted per year or 4% of the total population per year (1990–1994). Young-to-adult ratios calculated for the month of August during this study fluctuated around a baseline that averaged 6.1% a year (1990–2003). These ratios exceeded 8% for three different years (1995, 1996 and 2000). All three of these “good” recruitment years occurred after management began, and two of them were associated with zealous anti-poaching efforts that ultimately could not be sustained. After intensive management practices began in 1995, the August counts increased by about 37 individuals in two years (1995–1996) to an average 243 individuals, which remained almost constant up to 2003. Management practices included creation of a local conservation organization that coordinated environmental education, artificial nest construction, networking among stakeholders and with governmental authorities, and artificial and natural nest protection. Although Scarlet Macaw conservation efforts have been inconsistent since 1997, our study demonstrates that collaborative conservation by local stakeholders increased the population of this threatened species in 1995–1996, and from 1996 to present the population has sustained itself.

IMMOBILIZATION OF FREE-RANGING HOFFMANN'S TWO-TOED AND BROWN-THROATED THREE-TOED SLOTHS USING KETAMINE AND MEDETOMIDINE: A COMPARASION OF PHYSIOLOGIC PARAMETERS

Free-ranging Hoffmanns two-toed sloths (Choloepus hoffmanni; n=26) and brown-throated three-toed sloths (Bradypus variegatus; nequals;15) were manually captured and immobilized with 2.5 mg/kg ketamine + 0.02 mg/kg medetomidine administered intramuscularly. Physical examinations were conducted on each sloth 10 min after initial injection, and blood, fecal, and ectoparasite samples were collected. Heart rate, respiratory rate, body temperature, indirect systolic blood pressure, and indirect peripheral oxygen saturation were monitored every 5 min for the duration of anesthesia. After 45 min, atipamazole (0.1 mg/kg) was administered intramuscularly, as an antagonist to medetomidine, in order to facilitate recovery. All recoveries were smooth, rapid, and uneventful. Physiologic parameters were compared across time, gender, and species. All sloths, regardless of species and gender, demonstrated a time-dependent decrease in heart rate and blood pressure, and an increase in respiratory rate, during the course of anesthesia. Peripheral oxygen saturation was similar for all sloths over time. There were significant species differences for heart rate (Choloepus > Bradypus), respiratory rate (Choloepus > Bradypus), and systolic blood pressure (Bradypus > Choloepus), while there were significant gender differences for body temperature (males > females) and blood pressure (males > females). Results of this study suggest that the ketamine–medetomidine mixture, as described above, is a safe and effective anesthetic combination in free-ranging two- and three-toed sloths, although peripheral blood pressure should be monitored during anesthesia.

Development and characterization of 16 microsatellites for Hoffmann’s two-toed sloth, Choloepus hoffmanni

Hoffmann’s two-toed sloth (Choloepus hoffmanni) is an arboreal mammal found throughout the Neotropics. Due to its limited dispersal power and reliance on forested habitats, C. hoffmanni could serve as a model species for understanding the response of mammals to land cover change. To better understand sloth life history and their response to tropical forest fragmentation and loss, we developed and characterized 16 polymorphic microsatellite markers. We tested each locus with 16–23 C. hoffmanni individuals sampled in northeastern Costa Rica. The number of alleles per locus ranged from three to seven, while mean observed heterozygosity was 0.56 and ranged from 0.33 to 0.75. All loci met Hardy–Weinberg expectations and none of the loci exhibited significant linkage disequilibrium. The microsatellite markers developed herein will be used to investigate dispersal rates and gene flow among habitat patches in Costa Rica, as well as provide insights into the life history of two-toed sloths.

Isolation and characterization of 18 microsatellite markers for the brown-throated three-toed sloth, Bradypus variegatus

The brown-throated three-toed sloth (Bradypus variegatus) is an extremely sedentary arboreal mammal found in many Neotropical forests. Because of its low dispersal potential and ease in capture, it has the potential to serve as a model species to investigate the effects of land cover change in the Neotropics on gene flow and population connectivity. To better understand aspects of B. variegatus biology, such as mating system and dispersal rates, we isolated and characterized 18 polymorphic microsatellite markers. Markers were tested using 32 B. variegatus individuals sampled from a site in northeastern Costa Rica. Each locus contained between three and 12 alleles, while mean expected and observed heterozygosity were equal to 0.72. No loci deviated from Hardy–Weinberg equilibrium, and one locus was significantly linked to two others. These markers have sufficient polymorphism to identify individuals and assign parentage, and can further be used to investigate dispersal rates, mating structure, and other aspects of three-toed sloth ecology.

SEROSURVEY OF SELECTED ARBOVIRAL PATHOGENS IN FREE-RANGING, TWO-TOED SLOTHS (CHOLOEPUS HOFFMANNI) AND THREE-TOED SLOTHS (BRADYPUS VARIEGATUS) IN COSTA RICA, 2005-07.

Abstract We screened for antibodies to 16 arboviruses in four populations of free-ranging sloths in Costa Rica. Blood samples were taken from 16 Hoffmans two-toed sloths (HTSs; Choloepus hoffmanni) and 26 brown-throated sloths (BTSs; Bradypus variegatus) over a 3-yr period. We used serologic assays to detect antibodies against 10 arboviruses previously described in sloths (St. Louis encephalitis [SLEV], Changuinola, Venezuelan equine encephalitis, Ilheus [ILHV], Oropouche, Mayaro, Utinga, Murutucu, Punta Toro, and vesicular stomatitis [VSV] viruses) and six arboviruses not described in sloths (Rio Grande, West Nile [WNV], eastern equine encephalitis, Piry, Munguba, and La Crosse viruses). Overall, 80% of sloths had detectable antibodies to SLEV, 67% had antibodies to ILHV, 32% to Punta Toro virus, 30% to Changuinola virus, 15% to WNV, 14% to VSV, 11% to Venezuelan equine encephalitis virus, and 10% to Rio Grande virus. No samples had detectable antibodies to the remaining eight viruses. We found a significant increase in prevalence of antibody to VSV in HTSs between 2005 and 2007, and for WNV antibody between 2005 and 2006. We found no significant differences in the prevalences of antibodies to the sampled viruses between the two locations. Antibody prevalences were significantly higher in HTSs than in BTSs for SLEV in 2005. Antibody-positive results for ILHV were likely due to cross-reaction with SLEV. The novel finding of antibodies to Rio Grande virus in sloths could be due to cross-reaction with another phlebovirus. These findings might have implications for land management and domestic animal health. Due to the nature of the study, we could not determine whether sloths could represent amplification hosts for these viruses, or whether they were only exposed and could be used as sentinel species. Further studies are needed to fully characterize arboviral exposure in sloths.

Home range and habitat use of Basiliscus plumifrons (Squamata: Corytophanidae) in an active Costa Rican cacao farm

The home range, habitat use, and distance from water sources were estimated for Basiliscus plumifrons in an agricultural matrix in Costa Rica. Using radio telemetry, four females and four males were studied from July-September (2004) in a cocoa (Theobroma cacao) farm embedded in landscape dominated by banana and pineapple plantations. Females occupied a home range that averaged 1877 ± 1052 m2 (n = 4); male home ranges were similar, averaging 1740 ± 1288 m2 (n = 4; t-test = −0.12, P = 0.90). Cacao with a limited shade canopy was the predominant habitat available and used most frequently when compared to other habitats (χ2 = 116.67; P < 0.0001). Basiliscus plumifrons remained close to water although individuals occasionally traveled up to 80 m from water. However, both males (24.30 ± 1.93 m, n = 133) and females (26.82 ± 1.97 m, n = 128) maintained similar average distances from water resources (Kruskal-Wallis, H = 1.57, P = 0.20). Agroforestry systems connected to patches of riparian forest probably play an important role in the ecology and conservation of B. plumifrons.

Genetic patterns and conservation of the Scarlet Macaw ( Ara macao ) in Costa Rica

Once widely distributed throughout the lowland forests of Costa Rica, scarlet macaws (Ara macao) have been reduced to two major, geographically separated, populations along the Pacific slope. Past demographic declines raise conservation concerns regarding the detrimental effects of population fragmentation. This investigation aimed to evaluate the current status of scarlet macaws along the Pacific slope by examining levels of genetic variation and patterns of genetic structure within and among remnant populations. Statistical analyses using multilocus genotypes revealed strong differentiation between Central and South Pacific populations, suggesting local geographic barriers have historically restricted gene flow between these localities. High genetic diversity suggests neither population suffers from genetic erosion, likely resulting from relatively large population sizes and high dispersal capacity and longevity. However, evidence of disequilibrium within the Central Pacific population infers anthropogenic threats have disrupted natural population dynamics. These results advocate on focusing available resources on habitat restoration and nest protection, as a means to assist in reestablishing demographic stability and maintain the genetic health of wild scarlet macaws in Costa Rica.

PHYSIOLOGIC AND SERUM BIOCHEMISTRY VALUES IN FREE- RANGING HOFFMANN'S TWO-TOED (CHOLOEPUS HOFFMANNI) AND BROWN-THROATED THREE-TOED (BRADYPUS VARIEGATUS) SLOTHS IMMOBILIZED USING DEXMEDETOMIDINE AND KETAMINE

Dexmedetomidine, a highly selective alpha-2 adrenergic agonist and dextrorotary enantiomer of medetomidine, was combined with ketamine and used to immobilize 14 free-ranging Choloepus hoffmanni (Hoffmanns two-toed sloths) and 11 Bradypus variegatus (brown-throated three-toed sloths) in Upala, Costa Rica. Following intramuscular injection of ketamine (2.1 mg/kg) and dexmedetomidine (11 microg/kg), heart rate, respiratory rate, and indirect systolic blood pressure were measured every 5 min for a total of 25 min. An iStat (CG8+) was used to evaluate serum biochemical and hematologic values during anesthesia. After 30 min of anesthesia, atipamezole (0.13 mg/kg) was administered intramuscularly, which resulted in rapid and smooth recoveries. Mean heart rate and respiratory rate remained unchanged in both C. hoffmanni and B. variegatus over time. Progressive decreases in mean indirect systolic blood pressure were documented in both species. Results of this study suggest a combination of dexmedetomidne and ketamine is a safe and effective anesthetic protocol for use in free-ranging C. hoffmanni and B. variegatus. Similar to other alpha-2 adrenergic agonist-based immobilization protocols, close monitoring of cardiovascular and respiratory parameters are recommended. This study also provides serum biochemical and hematologic data in free-ranging C. hoffmanni and B. variegatus.