Scientific Papers

Animal & Population Management

Animal & Population Management

Reduction of Aggression in a Captive Prairie Dog Colony Through Observation and Underground Burrow Mapping (Byun et al., 2019)

August 11, 2019

Abstract: In 2015, staff at the Connecticut’s Beardsley Zoo reported seeing high levels of aggression within their exhibit prairie dog colony. Through RIZE (Research, Internships and Zoo Education), a service learning partnership between Fairfield University and The Connecticut’s Beardsley Zoo, we set out to better understand the potential sources of aggression by documenting the colony’s behavior and developing underground burrow maps, in order to minimize hostility and reduce instances of individual injury. Our observations and burrow maps suggest that this colony consists of two distinct coteries and that territorial food aggression between individuals of these different coteries was the principal cause of hostility. To test this hypothesis, we requested that zoo staff distribute the food within the enclosure so each of the two coteries had equal access to food.  The redistribution of food according to coterie boundaries resulted in a sudden and dramatic decrease in aggression and fighting within the captive prairie dog colony. This study underscores the importance of regular observational work in understanding the dynamics of multiple individual exhibits and highlights the positive and practical impact that programs like RIZE can have for institutions like zoos and aquariums.

Photo credit: Connecticut's Beardsley Zoo

Sexually Dimorphic Growth in the Western Swamp Tortoise, Pseudemydura umbrina (Testudines: Chelidae) (Durell & Keeley, 2019)

August 01, 2019

Abstract: Captive breeding of the critically endangered Western Swamp Tortoise (WST: Pseudemydura umbrina) has occurred at Perth Zoo as part of the species’ recovery plan since 1988. The first release of captive bred individuals took place in 1994.  Individuals are primarily released into protected wild reserves at approximately three years of age, when they typically reach the mandatory minimum body mass of 100g. They are sexually immature at this age, and gender determination is not possible by external physical examination. For sustainable reintroduction programs, it is desirable to know the sex ratio of individuals prior to release, and the sex of individuals being retained for future captive breeding purposes. Utilising body mass and size morphometrics from zoo bred individuals retained until sexual maturity, we evaluated sex related changes in growth rates and body size over time. Sexual dimorphism in favour of males was first detected at four years of age, with significant differences (P < 0.05) observed in both the body mass (121.9±6.8 g vs 105.0±4.4 g) and carapace length (89.5±2.0 mm vs 83.2±1.4 mm).  Age at which sexual maturity was attained varied between 5 to 13 years, but on average occurred earlier in males (8.0±0.5 yr) than females (8.7±0.4 yr). Data confirm a faster growth rate and earlier age of sexual maturity in males than females, as well as a smaller size (carapace length) at sexual maturity (~110 mm for males and ~100 mm for females) than previously reported for wild WST (110 – 131 mm).  We suggest that using growth rate data, body size (mass and length) and plastron shape may be useful to determine sex at 4-5 years of age, and prior to release to the wild, to better monitor sex ratios at release and during future in situ monitoring.

Photo credit: Perth Zoo

Comparative Personality Traits Assessment of Three Species of Communally Housed Captive Penguins (Pastorino et al., 2019)

June 23, 2019

Abstract: Understanding animal personalities has notable implications in the ecology and evolution of animal behavior, but personality studies can also be useful in optimizing animal management, with the aim of improving health and well-being, and optimizing reproductive success, a fundamental factor in the species threatened with extinction. Modern zoos are increasingly being structured with enclosures that host different species, which permanently share spaces. This condition has undeniable positive aspects, but, in some species, it could determine the appearance of collective or synchronized behaviors. The aim of this study was to verify, in a colony of three species of communally housed penguins (Pygoscelis papua, Aptenodytes patagonicus and Eudyptes moseleyi), through a trait-rating assessment, if interspecific group life impacts on the expression of personality traits, and if it is possible to highlight specie-specific expression of personality traits, despite the influence of forced cohabitation. For many of the personality traits we analyzed, we have observed that it was possible to detect an expression that differed, according to the species. From a practical point of view, these data could ameliorate the management of the animals, allowing to design animal life routines, according to the different behavioral characteristics of the cohabiting species.

Photo credit: Edinburgh Zoo

Investigating parental care behaviour in same-sex pairing of zoo greater flamingo (Phoenicopterus roseus) (Regaiolli et al., 2018)

June 13, 2019

Abstract: Same-sex pair bonds have been documented in several animal species and they are widespread in birds. However, little is known about the evolutionary origin and the adaptive value of such behaviour. The aim of this study was to investigate the parental behaviour of four zoo female greater flamingos involved in two breeding pairs, housed in a flock at Parco Natura Viva, Italy. Further, the behaviour of the study females was compared with that of male and female flamingos in heterosexual pairs described in a previous published work on this same flock. For each pair, the behaviour of both birds during the incubation period was recorded and twenty 10-minute sessions were run within the incubation period. A continuous focal animal sampling method was used to collect data on location (on the nest or not on the nest) and the parental care behaviour (e.g.: agonistic behaviours toward disturbing conspecifics, egg-care, nest-building, self-comfort behaviour, sleeping) of the two pairs. Data of the current study females were compared with those of females and males involved in heterosexual pairs of this same flock. Results showed that within each pair the egg-layer female stayed away from the nest more than the other female. In addition, the female that did not lay an egg was more involved in agonistic behaviour compared to other females, particularly when in specific locations. In heterosexual pairs, male flamingos were more involved in the incubation and in nest protection. Moreover, no significant differences in the time spent on the nest and away from the nest between the heterosexual male and the non-layer females of same-sex pairs were found. The same findings were reported when comparing heterosexual females and the egg-layer females of the same-sex pairs. Therefore, our findings suggest that in greater flamingos the behaviour of the female–female pairs seems to be equivalent to that of male-female bonds. Such research provides more insight into flamingo social behaviour, and their reproductive cycle, and provides information on why pair bonds may form and how these affect the wider breeding behaviour of the flock.

Photo: Same-sex male pair of greater flamingos at WWT (2007), acting as surrogates for an abandoned chick.

Genetic evaluation of the Iberian lynx ex situ conservation programme (Kleinman-Ruiz et al. 2019)

June 10, 2019

Abstract: Ex situ programmes have become critical for improving the conservation of many threatened species, as they establish backup populations and provide individuals for reintroduction and reinforcement of wild populations. The Iberian lynx was considered the most threatened felid species in the world in the wake of a dramatic decline during the second half of the 20th century that reduced its numbers to around only 100 individuals. An ex situ conservation programme was established in 2003 with individuals from the two well-differentiated, remnant populations, with great success from a demographic point of view. Here, we evaluate the genetic status of the Iberian lynx captive population based on molecular data from 36 microsatellites, including patterns of relatedness and representativeness of the two remnant genetic backgrounds among founders, the evolution of diversity and inbreeding over the years, and genetic differentiation among breeding facilities. In general terms, the ex situ population harbours most of the genetic variability found in the two wild populations and has been able to maintain reasonably low levels of inbreeding and high diversity, thus validating the applied management measures and potentially representing a model for other species in need of conservation.

Photo: Saliega in El Acebuche (2012) - the first female to give birth in the Iberian lynx breeding programme. She past away of natural causes last week, in Zoobotánico Jerez, but left behind a legacy in the conservation of her species! (Lynx ex-situ)

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