Bimodal nesting season in Karoo dwarf tortoises (Chersobius boulengeri)

Tortoises in arid, unpredictable regions may use a bet-hedging strategy of regularly laying small clutches regardless of actual environmental conditions so that some hatchlings will emerge when conditions are favourable. Karoo dwarf tortoises (Chersobius boulengeri) are endangered in their arid, unpredictable range in South Africa, yet studies of reproduction are lacking. I used radiography and captive breeding to study reproduction in wild (n = 22, 2018–2022) and captive (n = 2, 2020–2023) individuals, expecting to find bet-hedging characteristics. My expectation was that females would regularly lay eggs in summer when most rain falls. In addition, I expected that females would produce consistently large eggs and hatchlings capable of surviving their harsh environment. Indeed, females produced multiple clutches of large single eggs per year, some even during drought. However, the egg-laying season had a unique bimodal pattern in autumn and spring, possibly dispersing hatching events th..., Study site and recordings in the wild
The study site consisted of a rocky mountain slope (altitude ~1,400 m) with adjacent plateaus, exposed dolerite sills, and dry river beds in the Northern Cape Province of South Africa (Loehr, 2023b; due to the sensitivity of this population the coordinates are withheld here, but are recorded on the biodiversity database of CapeNature, Western Cape Province, South Africa). Long-term modelled (30 years of hourly weather simulations) climatic conditions show that the site is arid (annual rainfall 162 mm, largely falling in summer), with mean minimum and maximum monthly temperatures ranging between 1–14 and 14–30 °C, respectively (www.meteoblue.com). I placed data loggers (Hobo S-THB-M00x, RS3-B, and S-RGF-M002 connected to H21-USB; Onset Computer Corporation, Bourne, MA, USA) in the centre of the study site to record temperature and rainfall during this study.
Between 20 February and 8 March 2018, I captured 16 female tortoises through inspection of ho..., , # Bimodal nesting season in Karoo dwarf tortoises (*Chersobius boulengeri*)

[https://doi.org/10.5061/dryad.stqjq2ccd](https://doi.org/10.5061/dryad.stqjq2ccd)

## Description of the data and file structure

Female Karoo dwarf tortoises (*Chersobius boulengeri*) were sampled in the wild and radiographed, and two male and two female individuals were transferred to captivity for captive breeding. Captive-produced eggs and hatchlings were recorded. The Methods field of this submission contains details on how data were collected. All data are gathered in one xlsx file that contains four tabs.

### Files and variables

#### File: Reproduction\_raw\_data.xlsx

**Description:** Characteristics of wild females, recordings from radiographs, characteristics of captive females, characteristics of captive eggs and hatchlings, captive temperatures, and wild temperatures and rainfall.

##### Variables

* All variables in the xlsx file are spelled out in full and mention units of measurement.
* Cells ...