Captive Wood Research Articles

Advancing Forensic Chemical Analysis to Classify Wild and Captive Turtles

The diets and environments that individuals experience can vary greatly within and among wildlife populations. These individual experiences can be compared using the chemical signatures of animal tissues, which can differentiate animals into groups, including those raised in the wild versus those held in captive facilities. In this study, we compared different combinations of four stable isotope ratios and 15 trace elements derived from the claw tips of captive wood turtles throughout the eastern U.S. and wild wood turtles (Glyptemys insculpta) from Maine to develop predictive models used to determine their origins. The purpose of this work is to develop an objective statistical tool that law enforcement can use to help prosecute poachers. We found that the chemical signatures of 14 (12 trace elements and 2 stable isotope ratios) of the 19 markers we explored were different between wild and captive wood turtles, thus reflecting the differences in their diets and environments. We found that our stable isotope ratio model had nearly perfect predictive accuracy in classifying wild wood turtles as wild and captive wood turtles as captive, whereas our trace element and combined model were 100% accurate, thus validating this statistical approach for determining the origins of confiscated wood turtles from Maine.

Forensic Application of Stable Isotopes to Distinguish between Wild and Captive Turtles.

Wildlife traffickers often claim that confiscated animals were captive-bred rather than wild-caught to launder wild animals and escape prosecution. We used stable isotopes (δ13C and δ15N) derived from the claw tips of wild wood turtles from Maine and captive wood turtles throughout the eastern U.S. to develop a predictive model used to classify confiscated wood turtles as wild or captive. We found that the claw tips of wild and captive wood turtles (Glyptemys insculpta) were isotopically distinct. Captive turtles had significantly higher δ13C and δ15N values than wild turtles. Our model correctly classified all wild turtles as wild (100%) and nearly all captive turtles as captive (94%). All but two of the 71 turtles tested were successfully predicted as wild or captive (97.2% accuracy), yielding a misclassification rate of 2.8%. In addition to our model being useful to law enforcement in Maine, we aim to develop a multi-species model to assist conservation law enforcement efforts to curb illegal turtle trafficking from locations across the eastern United States and Canada.

Strategies for oocyte collection and in vitro embryo production in free-roaming bison herds.

The study was conducted to test the feasibility of protocols for field collection of cumulus–oocyte complexes (COC) for in vitro embryo production (IVP) in wild bison. The study was done with captive wood bison during the anovulatory season. In Experiment 1, the efficiency of transvaginal ultrasound-guided COC collection was compared between bison restrained in a squeeze chute without sedation vs in lateral recumbency after chemical immobilization using a dart gun (n = 8/group). In Experiment 2, a 2 × 2 design was used to examine the effects of superstimulation treatment [single dose of equine chorionic gonodotrophin (eCG) vs multiple doses of follicle stimulating hormone (FSH)] and method of drug administration (manual injection vs field darting) on COC collection and IVP. In Experiment 1, no difference was detected between chute-restrained vs chemically immobilized groups in the time required to complete COC collections, the number of follicles aspirated (11.5 ± 1.9 vs 9.3 ± 1.8; P = 0.4) or the COC recovery rate [COC recovered/follicle aspirated; 58/92 (63%) vs 44/69 (64%); P = 0.9]. In Experiment 2, no differences were detected between superstimulation treatments (eCG vs FSH). The total number of follicles available for aspiration did not differ between manual injection and field darting (23.9 ± 2.7 vs 21.6 ± 1.9; P = 0.4). Compared with the random start unstimulated group, the embryo production rate was higher [18/132 (14%) vs 53/189 (28%); P = 0.04] after wave synchronization and superstimulation. Results suggest that COC collection is equally feasible in a recumbent position after chemical immobilization as those bison restrained in a standing position in a hydraulic chute. Ovarian superstimulation with a single-dose eCG protocol is as effective as a multiple-dose FSH protocol, and field darting is as effective as chute-side administration of superstimulation treatments. The strategies in the present study are ready to be incorporated into field collections in free-roaming bison herds.

22 Strategies for oocyte collection procedures in free-roaming bison herds

The study was conducted to test the feasibility of protocols for field collection of cumulus–oocyte complexes (COC) for invitro embryo production (IVP) in wild bison. The study was done with captive wood bison during the late anovulatory season (July). In Experiment 1, bison were assigned randomly to 2 groups (n=8/group) in which transvaginal ultrasound-guided COC collection was done in a chute without sedation or in lateral recumbency after chemical immobilization using a dart gun to compare collection efficiencies. In Experiment 2, a 2×2 design was used to examine the effects of superstimulation treatments [single-dose equine chorionic gonadotrophin (eCG) vs. multiple-dose FSH] and methods of drug administration (manual injection vs. field darting) on COC collection and IVP. Initial COC collection was done to serve as a non-superstimulated random start and to synchronize follicular wave emergence on the following day (Day 0; n=16). Half of the bison were given a single dose of 5000IU of eCG intramuscularly (IM) on Day −1. The other half were given 200mg of FSH IM on Day 0 and Day 2, followed by 2000IU human chorionic gonadotrophin IM on Day 4. Superstimulatory treatments were given by manual injection (chute restrained) to half of the bison in each group and by field darting in the other half. The COC were collected on Day 4 in the eCG group and Day 5 in the FSH group. Recovered COC were matured invitro for 25 to 28h at 38.8°C, fertilized (2×106 sperm mL−1) and co-incubated at 38.8°C in 5% O2, 5% CO2, and 90% N2 for 18h. Presumptive zygotes were denuded and cultured at 38.8°C in 5% O2, 5% CO2, and 90% N2. A commercially available IVF media set was utilised (IVF Bioscience). Data were compared by ANOVA and GLIMMIX. In Experiment 1, no difference was detected between chute-restrained vs. chemically immobilized groups in the time required to complete COC collection (6.9±1.0 vs. 8.9±1.0 min; P=0.2), the number of follicles aspirated (11.5±1.9 vs. 9.3±1.8; P=0.4), or the COC recovery rate [COC recovered/follicle aspirated; 58/92 (63%) vs. 44/69 (64%); P=0.9]. In Experiment 2, no differences were detected between superstimulation treatments (eCG vs. FSH) or method of drug administration (manual injection vs. field darting) for any endpoint. The number of medium (4.5–7.5 mm; 9.5±1.0 vs. 2.5±0.6; P<0.0001) and large (>8 mm; 8.6±0.8 vs. 3.4±1.5; P=0.004) follicles available was greater after superstimulation (groups combined) than without superstimulation (random start). Although there was no difference in the number of recovered compact COC between the superstimulated and non-superstimulated bison (8.9±1.3 vs. 6.2±1.7; P=0.2), the embryo production rate (number of embryos produced/number of COC matured) was greater after superstimulation than without superstimulation [54/189 (39%) vs. 19/108 (18%); P<0.05]. We conclude that COC collection in a field setting is feasible and minimum-handling superstimulation with a single dose of eCG is as effective as a multiple-dose FSH protocol for the invitro production of embryos in bison. This research was supported by NSERC and Vetoquinol.

Cryoprotectant Production in Freeze-Tolerant Wood Frogs Is Augmented by Multiple Freeze-Thaw Cycles.

Ice nucleation across the skin of wood frogs (Lithobates sylvaticus) rapidly induces endogenous production of glucose, a cryoprotectant necessary for freeze tolerance. In laboratory studies of freeze tolerance, wood frogs are cooled slowly, often at -0.05°C h(-1), to facilitate high cryoprotectant production and survival. Under natural conditions in Alaska, however, wood frogs accumulate maximal tissue glucose concentrations while cooling at much faster rates, -0.35° to -1.6°C h(-1), and in addition undergo multiple successive freeze-thaw cycles before remaining frozen for the winter. We examined whether simulating these ecologically relevant cooling rates and repeated freeze-thaw events in captive wood frogs results in the high glucose concentrations found in naturally frozen wood frogs. We found that over successive freezing and thawing events, glucose concentrations increased stepwise in all measured tissues. Short thawing periods did not result in a statistically significant decline of glucose concentrations. Wood frogs that experienced three freeze-thaw events had fresh weight glucose concentrations that approached values found in tissues of wood frogs frozen in natural conditions. Laboratory wood frogs survive frozen for 2 mo, while wood frogs frozen under natural conditions survive frozen for up to 7 mo at temperatures below -18°C. We hypothesize that repeated freeze-thaw cycles with rapid cooling and warming rates allow for greater survival in Alaskan wood frogs through enhanced cryoprotectant production.

Wood frog adaptations to overwintering in Alaska: new limits to freezing tolerance.

We investigated the ecological physiology and behavior of free-living wood frogs [Lithobates (Rana) sylvaticus] overwintering in Interior Alaska by tracking animals into natural hibernacula, recording microclimate, and determining frog survival in spring. We measured cryoprotectant (glucose) concentrations and identified the presence of antifreeze glycolipids in tissues from subsamples of naturally freezing frogs. We also recorded the behavior of wood frogs preparing to freeze in artificial hibernacula, and tissue glucose concentrations in captive wood frogs frozen in the laboratory to -2.5°C. Wood frogs in natural hibernacula remained frozen for 193 ± 11 consecutive days and experienced average (October-May) temperatures of -6.3°C and average minimum temperatures of -14.6 ± 2.8°C (range -8.9 to -18.1°C) with 100% survival (N=18). Mean glucose concentrations were 13-fold higher in muscle, 10-fold higher in heart and 3.3-fold higher in liver in naturally freezing compared with laboratory frozen frogs. Antifreeze glycolipid was present in extracts from muscle and internal organs, but not skin, of frozen frogs. Wood frogs in Interior Alaska survive freezing to extreme limits and durations compared with those described in animals collected in southern Canada or the Midwestern United States. We hypothesize that this enhancement of freeze tolerance in Alaskan wood frogs is due to higher cryoprotectant levels that are produced by repeated freezing and thawing cycles experienced under natural conditions during early autumn.

The Hook Lake Wood Bison Recovery Project: can a disease-free captive wood bison herd be recovered from a wild population infected with bovine tuberculosis and brucellosis?

The Hook Lake Wood Bison Recovery Project (HLWBRP) is a wildlife conservation project aimed at recovering a captive, disease-free herd of wood bison (Bison bison athabascae) from a wild herd infected with bovine tuberculosis (Mycobacterium bovis) and brucellosis (Brucella abortus). The disease eradication protocol that we have used involves a combination of techniques, including (1) orphaning of newborn wild-caught calves to minimize exposure to B. abortus and M. bovis, (2) testing calves for maternal antibodies to brucellosis in the field prior to inclusion in the project, (3) isolating calves in pairs to prevent potential spread of disease, (4) prophylactic treatment using antimycobacterial and anti-Brucella drugs, and (5) an intensive whole-herd testing program for both diseases and removal of reactors. From 1996 to 1998, we captured a total of 62 calves; presently, 58 individuals comprise the founder herd. The captive-born cohorts consist of 7 two-year-olds, 21 yearlings, and 22 calves. To date, there have been no cases of bovine tuberculosis or brucellosis in the captive herd.

The Market Effect in the Wood Mouse,Apodemus sylvaticus:Selling Information on Reproductive Status

Grooming in the wood mouse is a means by which males obtain information about the reproductive state of females, as grooming creates a situation which allows the male to smell the groomed female’s anogenital area to ascertain her phase of oestrus. Although grooming is reciprocal in this species, it is asymmetrical in that males groom females more often than vice versa. This grooming asymmetry was studied using Markov chain analysis for grooming sequences in two captive wood mouse colonies, and transition rates were used to represent motivation in both sexes. Grooming sessions were often initiated by a male’s attempt to sniff an immobile female’s anogenital region, while the female would immediately react by avoiding or biting the male. In order to entice the female to remain, the male would begin grooming the female’s head and shoulder area, surreptitiously and consistently grooming downwards towards the female’s anogenital region, until she would again terminate such contact either by avoiding or biting the male. While, therefore, the male’s tendency to sniff the female’s anogenital region was stronger than his tendency to groom her, the female’s tendency to terminate the male’s naso‐anal contact was much stronger than her tendency to terminate his grooming bouts. If the male did not initiate grooming after the female terminated naso‐anal contact, she avoided further contacts and escaped. In mice, as in most mating systems, the demand for matings by males is far larger than the number of matings females offer. The mating market, therefore, is highly skewed, which gives females the opportunity to demand ‘commodities’ in return for allowing males to mate. This system allows females to ‘bargain’ with males to obtain grooming in return for anogenital contact. Females assess the length of time they receive grooming and will only allow males to attain anogenital contact after a certain threshold value has been passed. If anogenital contact provides the male with information about the female’s reproductive state and/or with sexual stimulation, then this process represents the first quantified example in short‐lived mammals of females ‘selling sex’ in terms of the market effect. This paper therefore provides a new view of the regulation of grooming: grooming is not simply reciprocal with both participants concerned that the other does not ‘cheat’ (e.g. tit‐for‐tat (TFT)‐like strategy), rather grooming is a commodity which can be bartered against female reproductive information or matings.

Body-Mass, Survival, and Pairing Consequences of Winter-Diet Restriction in Wood Ducks

We conducted feeding experiments with captive, wild-strain wood ducks (Aix sponsa) during winters 1990-91 and 1991-92 to test effects of increasing levels of food restriction on body mass dynamics, mortality, and pair formation. Male and female wood ducks fed restricted diets (i.e., 5, 10, 15, or 20% less food [g] than consumed on the previous day by a control group fed ad libitum) weighed less (P ≤ 0.037) than birds fed ad libitum; those on 15 and 20% restricted diets weighed least. Increased mortality and decreased pair formation occurred only within the 20% restricted group (P ≤ 0.049). We concluded that food restriction ranging between 15 and 20% of ad libitum intake may signify a threshold above which survival and reproduction of captive wood ducks may be impaired. Because energy costs of free living are greater than in captivity, a lower threshold may exist for wild wood ducks. Research is needed to validate the threshold theory for free-ranging wood ducks and other waterfowl, and to evaluate its potential application for conservation of winter foraging habitat. Conservation of bottomland hardwood ecosystems, which provide important foraging habitat for migrating and wintering wood ducks, should be encouraged to prevent potential negative effects on wood duck life-cycle events.

The effect of variation in calcium intake on the growth of wood mice and bank voles.

Calcium intake by wild rodents varies with season and habitat. This may have important ecological consequences; several studies have suggested that calcium availability may limit growth and reproduction. We studied the effect on growth of varying the calcium intake of captive wood mice Apodemus sylvaticus (L.) and bank voles Clethrionomys glareolus (Schreber 1780). To determine whether effects observed in the laboratory could be detected in free-living animals, we also compared the body weights and lengths of free-living animals on calcium-poor gritstone areas with those of rodents on calcium-rich limestone habitats where the dietary calcium concentration was between 2 and 5 times higher. Captive wood mice fed high calcium (0.87%) diet grew at the same rate as mice fed low calcium (0.30%) diet but continued growing for longer, thereby achieving higher asymptotic weights. In contrast, captive bank voles fed the high calcium diet grew more slowly and had lower asymptotic weights than voles fed the low calcium diet. As expected from the laboratory growth study, the higher calcium intake of free-living wood mice on the limestone was associated with greater body size compared with mice on the gritstone. However, bank voles were also larger on the limestone, even though high calcium intake impaired growth in captive animals. The contrast between wood mice and bank voles in the effects of calcium on growth, the reason why impaired growth may not be apparent in bank voles from calcium-rich habitats and the ecological significance of these results are discussed.

Wood-fired power plants in the Philippines: Financial and economic assessment of wood-supply strategies

To help reduce its dependence on imported oil, the Philippines is constructing over 60 wood-fired electricity generating plants. Nine power plants are now operational, but financial difficulties are hindering the development of wood-supply networks. This study found that financial and economic costs of the current strategy promoting the development of captive wood supplies exceed the costs of open-market wood at a majority of the project sites. Plantation establishment and wood transport are the most costly activities associated with producing captive wood. Sensitivity analysis indicates that the total unit costs of captive wood are most responsive to changes in plantation yields. Future changes in the costs of labor (within a reasonable range) would have little impact on wood costs. Although many open-market suppliers can provide wood at a cost lower than that produced under the current approach, any policy shift favoring open-market wood procurement must include provisions to guard against adverse environmental effects.

Hatchability Tests with Eggs from Captive Wood Ducks

The effect of diet and artificial incubation on fertility and hatchability of wood duck (Aix sponsa) eggs and survival of young was measured. Hatchability of eggs from hens fed a diet containing 37 percent protein was increased significantly (P<0.05) over that of hens fed a diet containing 17 percent protein. Hatchability was also significantly (P<0.005) greater for eggs incubated 10 days under hens before being placed in an incubator than for eggs placed in an incubator for the entire period. Ducklings that hatched from naturally started incubation survived at a much higher rate (P<0.001). Egg fertility was not affected by the diets.

Notes on the opening of hazel nuts (Corylus avellana) by mice and voles

A difference was noticed in the type of hole made by captive wood mice (Apodemus sylvaticus) and bank voles (Clethrionomys glareolus) when opening hazel nuts. To find the reason for this they were observed when actually opening the nuts.