Observation of the Breeding Behavior of the Chinese Giant Salamander (Andrias davidianus) Using a Digital Monitoring System

Abstract

Simple SummaryBehavioral research on wild Chinese giant salamanders (Andrias davidianus) is in its infancy because A. davidianus inhabit underground river dens that are difficult to access. In order to ascertain the types of reproductive behavior exhibited by A. davidianus, this paper monitored their reproductive activity using a digital monitoring system in a simulated natural habitat. The survey uncovered reproductive behavior such as sand-pushing, showering, courtship, oviposition, and parental care. We also recorded the parental care time allocation for the first time. This study provides a scientific basis for the method optimization for the ecological reproduction of A. davidianus and the conservation of its wild population. This study also demonstrates that a digital monitoring system is an effective research method for investigating the behavior of Cryptobranchidae and other cave animals.AbstractKnowledge of natural animal behavior is essential for enhancing the protection and artificial breeding of animals. At present, the behavior of the Chinese giant salamander (Andrias davidianus) is studied through interviews with local people or occasional observations under artificial conditions, leading to a lack of systematic records. Thus, most reports are descriptive and lack quantitative analyses. To ascertain the types of reproductive activities and their corresponding time allocations, this study observed the reproductive behavior of A. davidianus using a digital monitoring system for the first time. The results showed that sand-pushing behavior is mainly carried out by the limbs, tail, head, and body of den-dominant males. Showering behaviors included rinsing the trunk, head, and tail. Courtship was composed of a series of behaviors, including standing side-by-side, belly colliding, mounting, mouth-to-mouth posturing, chasing, inviting, cohabitating, and rolling over. After chasing and interlocking with the male, the female discharged her eggs. The oviposition process began at either 02:04 or 04:09, and lasted either 66 or 182 min. Parental care included tail fanning, agitation, shaking, and eating dead and unfertilized eggs, and the durations of these behaviors accounted for 31.74 ± 4.35%, 17.42 ± 4.00%, 3.85 ± 1.18%, and 1.19 ± 0.69% of the entire incubation period, respectively. This paper reveals the characteristics of the reproductive behavior of A. davidianus and provides a scientific basis for the management of its ecological breeding and the conservation of its wild populations.

Middle Jurassic stem hynobiids from China shed light on the evolution of basal salamanders

“…Our data suggest that caudosacral counts and, by implication, cloacal positions have changed at least twice during the evolution of crown salamanders: initially with the origin of internal fertilization in salamandroids and again during subsequent evolution within salamandroids and cryptobranchoids. In the externalfertilizing cryptobranchid Andrias davidianus, during oviposition, the female deposits eggs in her den after the male butts her sides with his head and then, with their tails crossed, the male fertilizes the eggs by ejaculating his sperm into the water (Luo et al, 2018). By contrast, in internal fertilizing species, the male either deposits spermatophores (gelatinous structure with a cap of sperm and a base consists of viscous secretions from the male cloaca) directly into the female's cloaca or places the spermatophore on the substrate near the female, who then positions herself over the spermatophore and lowers her cloaca so that most of the spermatophore or only the sperm cap of the spermatophore is picked up by her cloacal lips.…”

Real-Time Monitoring on the Chinese Giant Salamander Using RPA-LFD

“…Conducting field investigations to understand the distribution of A. davidianus populations is crucial for protecting their habitats and formulating effective conservation strategies. Traditional population monitoring methods of A. davidianus primarily involve 2 of 14 visual surveys, such as trapping, rock turning, nocturnal snorkeling, and spotlighting surveys [9,10]. However, the rare and elusive nature of A. davidianus, which typically resides in inaccessible environments like riverbanks or underground river caves, renders these methods largely ineffective [11,12].…”

Ethogram of the Chinese Giant Salamander during the Breeding Period Based on the PAE Coding System

“…A few quantitative studies on A. davidianus's behavior have been conducted. Luo et al systematically reported five categories of reproductive behaviors of A. davidianus, including sand pushing, showering, courtship, oviposition, and parental care, and quantified the frequency [29]. In addition, the relationship between spawning, parental care, and water quality was also analyzed [30].…”