Bat species richness and activity in Dghoumes National Park (Southwest Tunisia): a preliminary survey

Study Extent

Dghoumes National Park (34º 01' N–34º 06' N, 8º 28' E–8º 39' E) is located 30 km east of Degueche (Tozeur governorate, southwest Tunisia) (fig. 1). The park covers approximately 8,000 ha. It borders with Chott el–Jérid in the south and the mountain ridge of Jebel Morra, Jebel El Kebiriti and Jebel Taferma in the north. The southern flank of the mountain range is cut through by wadis (Tamaxid, El Akreb, El Behim, El Kebiriti, Bou Moussa, El Oussif) that flow to Chott el–Jérid across a broad sandy plain (3,800 ha). The park has two small hillside lakes (Marzoug and Tamxid basins) and several permanent ponds (Sassia pond, El Kebiriti pond, and others). The bioclimate is arid with cool winters. The annual rainfall is about 100 mm/year. The average temperature ranges from –3 ºC in winter to more than 50 ºC in the summer. Evaporation reaches 1,200 mm/year. The sirocco wind blows for more than 50 days/year, especially in the summer (A. Chetoui, pers. comm.). The dominant biome is steppe with herbaceous vegetation such as Suaeda mollis, Zygophyllum album, Salsola tetrandra, Traganum nudatum, Artemisia campestris, Rhus tripartitum, Periploca laevigata and Retama retam, and sparse trees of Acacia tortilis raddiana and Tamarix aphylla. The main terrestrial mammals are Ctenodactylus gundi, Hyaena hyaena, Lepus capensis, Ammotragus lervia and reintroduced Oryx dammah and Gazella dorcas (Jebali, 2012).

Sampling

Data collection and species identification From June 16 to 24, 2018, we studied bat activity at eight sites of Dghoumes National Park (fig. 1): 1) at the main entrance to the park, which is illuminated by solar white streetlamps (34º 2' 30.62'' N, 8º 33' 51.95'' E); 2) at Tamxid basin (34°º 3' 53.93'' N, 8º 31' 13.27'' E) with a wet sludge; 3) at Marzoug basin (34º 3' 57.73'' N, 8º 29' 38.31'' E) with a dry sludge; 4) at El Kebiriti pond (34º 3' 57.19'' N, 8º 33' 8.42'' E); 5) at Sassia pond (34' 4º 15.44'' N, 8º 31' 13.24'' E); 6) at Jmal Ribeh pond (34º 4' 14.80'' N, 8º 29' 55.83'' E) surrounded by phragmites and sunk into high banks; 7) at the dry wadi El Oussif (34º 2' 53.24'' N, 8º 33' 31.56'' E) with some retama bushes; and 8) at a plain (34º 2' 55.13'' N, 8º 33' 59.12'' E) characterized by sparse vegetation and five small water bodies.

Quality Control

Statistical analyses Bat activity was estimated by counting the number of passes (Russo and Jones, 2003). A bat pass was defined as a single or several calls emitted by a single animal during a 5 s interval (Barataud, 2012). Within each night, we considered 19 periods of 30 minutes to investigate activity patterns; the number of bat passes recorded during each period was used as a proxy of bat activity. Call recordings were used to calculate species richness at each site. Bat community analysis was performed using the number of bat passes. We used Kruskal–Wallis tests, followed by post–hoc multiple comparison tests, and Friedman tests to assess differences in bat activity among sites and periods. Statistical analyses were performed with Tanagra v.5, ’97 edition (Rakotomalala, 2005).

Method steps

1. Each site was surveyed for one night under similar hot and dry weather conditions. We usedautomatic echolocation call recordings at fixed points starting 30 minutes before sunset and lasting 30 minutes after sunrise. A Song Meter SM2BAT+ recorder (Wildlife Acoustic, Inc. Concord, Massachusetts, U.S.A.) was connected to a BMX–US1 ultrasonic microphone by a 3 m cable (Biotope, France). Real–time recordings were made at a sampling frequency of 384 kHz and an activation frequency of –18bB and 8 Hz. Recorded sequences were unzipped, analyzed and split into 5–second sequences with Kaleidoscope (Wildlife Acoustic, Inc. Version 4.1.0a). Only 5–second sequences containing bat calls were analyzed using the real–time analysis software BatSound, v.3.10 (Petterson Elektronik AB) for spectrogram analyses. We used a simple frequency of 38,400 samples/s, 16 bits/sample and selected 512 pt FFT with a Hamming window for analysis (Russ, 1999). Recorded calls, including feeding and drinking buzzes, were manually identified to species level using shape and other call parameters (Barataud, 2012). Echolocation calls of Tadarida teniotis, Eptesicus isabellinus, Pipistrellus kuhlii and Rhinopoma cystops were identified using reference calls collected in various sites in Tunisia (Dalhoumi et al., 2014, 2016, 2019). Asellia tridens uses a typical signal with constant frequency at 108–122 kHz (Jones et al., 1993). Vansonia rueppellii was identified by shallow FM/QCF calls at a frequency of maximum energy of 53.6 ± 1.3 kHz (Disca et al., 2014). A specimen of this species has been previously mist–netted at the entrance of the park and recorded after release during a visit on April 2, 2010. Additionally, temperature and hygrometry were recorded every 30 minutes during the nights of June 17–18 and 21–22 using a C.A. 846 pocket thermo–hygrometer (Chauvin Arnoux, Taiwan; precision ± 0.5 ºC and ± 2.5 % RH) for potential bat roosts in caves, crevices and buildings, and visually counted emerging or resting individuals.

1. Hipposideridae
   rank: family
2. Vespertilionidae
   rank: family
3. Rhinopomatidae
   rank: family
4. Molossidae
   rank: family
5. Vansonia rueppellii
   rank: species
6. Tadarida teniotis
   rank: species
7. Rhinopoma cystops
   rank: species
8. Pipistrellus kuhlii
   rank: species
9. Eptesicus isabellinus
   rank: species
10. Asellia tridens
    rank: species

Dghoumes National Park (34º 01' N–34º 06' N, 8º 28' E–8º 39' E) is located 30 km east of Degueche (Tozeur governorate, southwest Tunisia) (fig. 1). The park covers approximately 8,000 ha. It borders with Chott el–Jérid in the south and the mountain ridge of Jebel Morra, Jebel El Kebiriti and Jebel Taferma in the north. The southern flank of the mountain range is cut through by wadis (Tamaxid, El Akreb, El Behim, El Kebiriti, Bou Moussa, El Oussif) that flow to Chott el–Jérid across a broad sandy plain (3,800 ha). The park has two small hillside lakes (Marzoug and Tamxid basins) and several permanent ponds (Sassia pond, El Kebiriti pond, and others).