The complexity of the habitat refers to its physical geometry, which includes abiotic and biotic elements. Habitat complexity is important because it allows more species to coexist and, consequently, more interactions to be established among them. The complexity of the habitat links the physical structure of the enclosure to the biological interactions, which occur within its limits. Enclosure complexity should vary temporally, to be able to influence the animals in different ways, depending on the period of the day and season and throughout the year. In the present paper, we discuss how habitat complexity is important, and how it can positively influence the physical and mental states of zoo animals. We show how habitat complexity can ultimately affect educational projects. Finally, we discuss how we can add complexity to enclosures and, thus, make the lives of animals more interesting and functional.

We performed a bibliometric analysis to investigate the efficiency of release techniques (soft and hard–release), to analyse the characteristics and outcomes of the translocation programs, to identify knowledge gaps, and to provide recommendations. Animal conservation studies involving animal release to the wild increased significantly over the 31 years studied and were more frequently performed with terrestrial mammals than with other taxonomic groups. Most of the studies were performed by researchers from developed countries. Translocations occurred mostly in temperate regions, with almost no translocations occurring in the tropics. Almost 60 % of the studies did not provide information regarding the success or failure of the translocation programs. The most commonly used technique was hard release. Wild–caught specimens were preferred for translocations. Translocation programs were less common for groups like amphibians, fishes, and invertebrates. If criteria for suitable translocation are met, this management tool should also be conducted for tropical threatened species, led by native researchers. Furthermore, criteria for successful translocation should be clearly identified in order to improve future conservation actions.

The number of animal species threatened with extinction are increasing every year, and biologists are conducting animal translocations, as one strategy, to try to mitigate this situation. Furthermore, researchers are evaluating methods to increase translocation success, and one area that shows promise is the study of animal personality. Animal personality can be defined as behavioral and physiological differences between individuals of the same species, which are stable in time and across different contexts. In the present paper, we discuss how animal personality can increase the success of translocation, as well as in the management of animals intended for translocation by evaluating personality characteristics of the individuals. Studies of the influence of birthplace, parental behavior, stress resilience, and risk assessment can be important to select the most appropriate individuals to be released. Finally, we explain the two methods used to gather personality data.