After short interbirth intervals, captive callitrichine monkeys have higher infant mortality.

Life history theory predicts a trade-off between the quantity and quality of offspring. Short interbirth intervals-the time between successive births-may increase the quantity of offspring but harm offspring quality. In contrast, long interbirth intervals may bolster offspring quality while reducing overall reproductive output. Further research is needed to determine whether this relationship holds among primates, which have intensive parental investment. Using Cox proportional hazards models, we examined the effects of interbirth intervals (short, normal, or long) on infant survivorship using a large demographic dataset (n = 15,852) of captive callitrichine monkeys (marmosets, tamarins, and lion tamarins). In seven of the nine species studied, infants born after short interbirth intervals had significantly higher risks of mortality than infants born after longer interbirth intervals. These results suggest that reproduction in callitrichine primates may be limited by physiologic constraints, such that short birth spacing drives higher infant mortality.

A comparative study of litter size and sex composition in a large dataset of callitrichine monkeys.

In many birds and mammals, the size and sex composition of litters can have important downstream effects for individual offspring. Primates are model organisms for questions of cooperation and conflict, but the factors shaping interactions among same-age siblings have been less-studied in primates because most species bear single young. However, callitrichines (marmosets, tamarins, and lion tamarins) frequently bear litters of two or more, thereby providing the opportunity to ask whether variation in the size and sex composition of litters affects development, survival, and reproduction. To investigate these questions, we compiled a large dataset of nine species of callitrichines (n = 27,080 individuals; Callithrix geoffroyi, Callithrix jacchus, Cebuella pygmaea, Saguinus imperator, Saguinus oedipus, Leontopithecus chrysomelas, Leontopithecus chrysopygus, Leontopithecus rosalia, and Callimico goeldii) from zoo and laboratory populations spanning 80 years (1938-2018). Through this comparative approach, we found several lines of evidence that litter size and sex composition may impact fitness. Singletons have higher survivorship than litter-born peers and they significantly outperform litter-born individuals on two measures of reproductive performance. Further, for some species, individuals born in a mixed-sex litter outperform isosexually-born individuals (i.e., those born in all-male or all-female litters), suggesting that same-sex competition may limit reproductive performance. We also document several interesting demographic trends. All but one species (C. pygmaea) has a male-biased birth sex ratio with higher survivorship from birth to sexual maturity among females (although this was significant in only two species). Isosexual litters occurred at the expected frequency (with one exception: C. pygmaea), unlike other animals, where isosexual litters are typically overrepresented. Taken together, our results indicate a modest negative effect of same-age sibling competition on reproductive output in captive callitrichines. This study also serves to illustrate the value of zoo and laboratory records for biological inquiry.

An Animal Welfare Risk Assessment Process for Zoos.

There is a growing interest and need for zoos to develop and implement welfare assessment tools that are practical to use and provide meaningful results that can inform management decisions. This paper presents a process that was developed to support this type of evidence-based management in zoo animal welfare. The process is configured to facilitate institutional risk assessment, using an adapted version of the Five Domains Model for animal welfare assessment. It is designed to systematically analyse information gathered from zoo personnel in order to highlight areas of welfare risk, as well as areas that are performing well and areas requiring further investigation. A trial was conducted on three zoos over three years. Results of the trial suggest the process developed is practical and effective in identifying areas of welfare risk in a wide range of species in a zoo setting. It represents a further step towards achieving high-level animal welfare in zoos by integrating animal welfare as an institutional priority. The more zoos that employ such strategies, the greater the ability of the sector to advance the welfare of the animals in their care.

Species management benchmarking: outcomes over outputs in a changing operating environment.

Species management has been utilized by the zoo and aquarium industry, since the mid-1990s, to ensure the ongoing genetic and demographic viability of populations, which can be difficult to maintain in the ever-changing operating environments of zoos. In 2009, the Zoo and Aquarium Association Australasia reviewed their species management services, focusing on addressing issues that had arisen as a result of the managed programs maturing and operating environments evolving. In summary, the project examined resourcing, policies, processes, and species to be managed. As a result, a benchmarking tool was developed (Health Check Report, HCR), which evaluated the programs against a set of broad criteria. A comparison of managed programs (n = 98), between 2008 and 2011, was undertaken to ascertain the tool's effectiveness. There was a marked decrease in programs that were designated as weak (37 down to 13); and an increase in excellent programs (24 up to 49) between the 2 years. Further, there were significant improvements in the administration benchmarking area (submission of reports, captive management plan development) across a number of taxon advisory groups. This HCR comparison showed that a benchmarking tool enables a program's performance to be quickly assessed and any remedial measures applied. The increases observed in program health were mainly due to increased management goals being attained. The HCR will be an ongoing program, as the management of the programs increases and goals are achieved, criteria will be refined to better highlight ongoing issues and ways in which these can be resolved.