Moon phases influence encounters of anurans in the Brazilian semi-arid region of Piauí

The lunar cycle is associated with the behaviour of amphibians, influencing vocalization, reproductive behaviours, and environmental choices. In the present work, we aimed to answer some questions regarding the influence of lunar phases and their interference with the behaviours of semiarid anuran species in Piauí, Brazil. The work was carried out in the municipality of Floriano (S 6°30’; W 43°42’), and an active search was carried out for the inventory, with weekly campaigns from June 2018 to June 2019. The days were transformed into Julian days, and the sampling corresponding to 365.25 Julian days were transformed into degrees (Julian Day*360/365). The absolute occurrence by species was classified as constant, accessory, and accidental. In the circular statistics the Rayleigh test (Z) was applied to verify that there is no randomness, with the sample being considered unidirectional if the calculated interval corresponds to z≥z (α) and P=0.01. Sample sufficiency was estimated using the RAO’S (U) spacing test, with the value considered random when U<U (α) and P= 0.01. During the 13 months of sampling, 1,921 individuals were recorded in 12 species. Rhinella diptycha was the species with the highest record (constant species), and Physalaemus albifrons was the one with the lowest record of occurrence (accidental species). It was possible to deduce that most of the species (60%=6 of 10 species evaluated) present a greater occurrence between 270°–0°–90°, that is, the lunar albedo with less clarity. Four species were considered constant; two were considered accessory species and six, species with accidental occurrence. Studies with the lunar synodic cycle are important, as they help to understand the mechanisms of interaction between anuran species and the environment.

月相周期与两栖动物的行为密切相关，可对其鸣叫行为、繁殖行为以及生境选择产生影响。
本研究旨在解答有关月相及其对巴西皮奥伊州半干旱地区无尾两栖类（Anura）行为影响的相关问题。
本研究于巴西皮奥伊州弗洛里亚诺市（南纬6°30′；西经43°42′）开展，采用主动搜寻法进行物种编目，于2018年6月至2019年6月期间开展每周一次的野外调查。将调查日期转换为儒略日（Julian Day），并将对应365.25个儒略日的采样数据转换为角度值，计算公式为：角度值=儒略日×360/365。
基于物种的绝对出现频次，将其划分为常驻种、附属种与偶见种三类。在圆形统计分析中，采用瑞利检验（Rayleigh test，Z值）验证数据不存在随机性：当计算得到的Z值满足Z≥Z(α)且P=0.01时，判定样本数据呈单向分布。采用劳间距检验（RAO’S spacing test，U值）评估采样充分性：当U<U(α)且P=0.01时，判定采样数据呈随机分布。
本次为期13个月的采样共记录到12个物种、1921个个体。其中，Rhinella diptycha为记录量最高的常驻种，Physalaemus albifrons为出现频次最低的偶见种。
研究结果表明，在评估的10个物种中，有60%（即6个物种）的出现高峰集中于270°–0°–90°区间，也就是月面反照率较低的新月前后时段。
本次研究共划分为4个常驻种、2个附属种以及6个偶见种。
针对朔望月周期的研究具有重要意义，有助于阐明无尾两栖类与环境之间的相互作用机制。