Behavioral Assessment of Six Reptile Species during a Temporary Zoo Closure and Reopening

Abstract

Although reptiles are commonly housed in zoos and aquariums, their welfare is understudied for the diversity of species housed and the taxon's current captive population size. The sensory abilities of reptiles have adapted to the varied ecological niches they inhabit, and these evolutionary adaptations impact how reptiles perceive the stimuli around them-including zoo visitors. This study aimed to assess visitor effects on small groups of six reptile species during a temporary zoo closure due to COVID-19 by measuring behavioral diversity, use of space (measured by a spread of participation index), and select behaviors. The species assessed showed diverse responses. The Catalina Island rattlesnakes (Crotalus catalinensis) demonstrated increased investigation and behavioral diversity after the zoo reopened compared to when the zoo was closed, but the European glass lizards (Pseudopus apodus) showed decreases in the amount of time spent exposed to the observers' view and in their evenness of space use after the zoo was reopened to visitors. The other species, including beaded lizards (Heloderma horridum), Sonoran spiny-tailed iguana (Ctenosaura macrolopha), Arrau turtles (Podocnemis expansa), and dwarf caimans (Paleosuchus palpebrosus), had intermediate changes in their responses to visitor presence.

Keywords: COVID-19; reptile welfare; visitor effects; zoo animal behavior.

Figure 1

Boxplot for all significant differences within a species in the Shannon–Wiener Index (H) when the zoo was closed vs. open. For H, lower values indicate a lower variety of behaviors. The mean of each condition is represented by an “×”. Significant differences of Pr > |S-Mean| equal to 0.01 or below are indicated with a double asterisk (**).

Figure 2

Scatterplot with a trendline comparing the daily rate of visitor-glass interaction and the daily percent of time visible for the group of European glass lizards. Each point represents a single day for the group.

Figure 3

Boxplot for all significant differences within a species in the Dickens’ Spread of Participation Index (SPI) when the zoo was closed vs. open. For SPI, lower values mean more even space use. The mean of each condition is represented by an “×” and all outliers are indicated by circles. Significant differences (Pr > |S-Mean| below 0.05) are indicated with an asterisk (*), and Pr > |S-Mean| of 0.01 or below are indicated with a double asterisk (**).