This dataset contains the data of male (Austruca perplexa) waves produced towards females within a 30 s period in peak and off-peak breeding periods which is described in the paper: ‘Tina FW, Muramatsu D (2021) Small males of the fiddler crab Austruca perplexa court more in the off-peak breeding period when large males court less. Journal of Ethology, https://doi.org/10.1007/s10164-021-00703-4’. 

The data were collected to show how Austruca perplexa males adjust the rate of courtship waving in relation to their relative body size in the local population and/or the body size of females (potential mates) in peak and off-peak breeding periods. 

Explanation of the dataset: "obs.date" indicates observed date, "period" indicates the peak or off-peak breeding period, "m.CW" indicates male carapace width (mm), "m.SC" indicates the size class of males, "f.CW" indicates female carapace width (mm), "f.SC" indicates the size class of females, "wav.rate" indicates the number of waves per minute, "waves" indicates wave counts within 30 seconds (observed time), "tide" indicates the days from the spring lowest tide, "p.ID" indicates pair ID (the pair of waving male and audience female), respectively. 

Main results of this study are that (1) large males produced more waves in the peak breeding period than in the off-peak period and their waving rates were higher towards large females than towards small females, but (2) small males produced more waves in the off-peak breeding period and their waving rates were not different towards large or small females.

Our findings suggest that waving more in the off-peak breeding period may increase the chance of small males to acquire females rather than competing against large males during the peak breeding period.

All the data were obtained from the population of Austruca perplexa at Ban Nai Thung intertidal mudflat in Thasala District (8°38′41.76″N; 99°57′04.54″E), Nakhon Si Thammarat Province in southern Thailand in April (peak breeding period) and December (off-peak breeding period), 2019 on the third, fourth, and fifth tidal days after the spring tide. In both periods, 30 large males (15 were waving towards large females and 15 were waving towards small females) and 30 small males (15 were waving towards large females and 15 were waving towards small females) were randomly selected by visual observation and their waving display was video recorded for 30 s. After finishing each video recording, both the waving male and audience female were caught to measure their body size. Large and small crabs were decided based on the mean carapace width of the crab population; males smaller than 14 mm and females smaller than 13 mm in carapace width were treated as “small” and other crabs were treated as “large”. From the video recordings, the number of male waves within the 30 s period was counted and the waving rate (male waves/min) was calculated. The data were analysed by glmmML (generalised linear models with clustering), t-tests, and Spearman rank correlations.

Please contact Journal of Ethology (https://www.springer.com/journal/10164/contact-the-journal) for secondary use of this dataset.