Journal of Arid Environments 185 (2021) 104327 Contents lists available at ScienceDirect Journal of Arid Environments journal homepage: www.elsevier.com/locate/jaridenv African wild ass drinking behaviour on the Messir Plateau, Danakil Desert, Eritrea Redae T. Tesfai a,b,*, Francesca Parrini b, Norman Owen-Smith b, Patricia D. Moehlman c a Ministry of Agriculture/Forestry and Wildlife Authority, P. O.Box 1048, Asmara, Eritrea b Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa c EcoHealth Alliance, 460 West 34th St, New York, NY, 10001-2320, USA ARTICLE INFO ABSTRACT Keywords: The critically endangered African wild ass (Equus africanus) occurs in the Danakil Desert of Eritrea and Ethiopia. Danakil ecosystem Drinking behaviour and the costs of accessing water are critical to understanding how this threatened equid Equus africanus survives in an arid environment. Drinking data and distance travelled to water of 24 females and fivemales were Drinking frequency recorded for 83 days during four study years. Drinking frequency per individual per water source was obtained Lactating females by calculating the number of water visits of an individual per successive days of observation. The travel distance Travel distance to access water to water was estimated by measuring the distance between the morning foraging location and the water point. During the dry months, female African wild ass with young foals visited permanent water once a day, travelled on average 9 km and drank only at night. Non-reproductive adult females and males travelled to water every 5–10 days. In rainfall months, females with young foals drank twice a day and on average travelled 3 km to water, but dispersed up to 7 km from temporary water sources when livestock arrived annually. This spatial exclusion from water sources due to livestock presence may reduce female African wild ass ability to provide sufficient milk to their foals. 1. Introduction to 3 months) female Grevy’s zebra were usually observed within 2 km of water, while non-lactating females were seen up to 15 km from water Drinking and accessibility to surface water is critical for ungulates in (Becker and Ginsberg, 1990). Lactating Grevy’s zebra visited water at arid environments (Pratt and Gwynne, 1977; De Boer and Prins, 1990; twice the frequency of non-lactating females and tended to remain closer Sirot et al., 2016). Equids in particular, both arid- and mesic-adapted, to water during the foal’s firstthree months (Ginsberg, 1988; Becker and are dependent on water and this strongly influences their distribution Ginsberg, 1990). Hypothetically, females with foals of age less than and behaviour (Becker and Ginsberg, 1990; Schoenecker et al., 2016). three months would be at the peak of lactation and need to drink more They may reduce their movement distances (Western, 1975; Pratt and frequently than other adults. During this period the foal is almost Gwynne, 1977) and remain closer to water compared to other herbi­ entirely dependent on its mother for fluid( Ginsberg, 1988). Plains zebra vores (Becker and Ginsberg, 1990), or alternatively may need to move (Equus quagga) live in relatively mesic habitats and visit water points long distances to find forage (Becker and Ginsberg, 1990; De Leeuw every one or two days, but lactating females make more frequent trips to et al., 2001). Mountain zebra (Equus zebra) living in dry areas of water and this may limit their access to forage (Becker and Ginsberg, southern African (Watson et al., 2005; Penzhorn and Novellie, 1991) are 1990; Sundaresan et al., 2008). highly dependent on daily access to water (Joubert and Louw, 1976 Access to adequate forage near to water sources is critical for cited in Schoenecker et al., 2016), and their home range expands when lactating female maintenance and foal survival in arid habitats (Wil­ more water points are available (Novellie et al., 2002). liams, 1998, 2002). It is therefore important to document the drinking Access to water and forage is crucial for a lactating female’s main­ behaviour of African wild ass in relation to water sources, with partic­ tenance and ability to provide milk for her foal (Loudon and Kay, 1984). ular attention to females with foals, which is crucial for the long-term Grevy’s zebra (Equus grevyi) live in an arid environment, such as the conservation of this species. The African wild ass is listed as ‘Critically Samburu Game Reserve, in northern Kenya. During peak lactation (birth Endangered’ by the IUCN Red List (Moehlman et al., 2015) and an * Corresponding author. University of the Witwatersrand, School of Animal, Plant and Environmental Sciences, Johannesburg, South Africa. Tel.: 0027798018450 E-mail addresses: [email protected], [email protected] (R.T. Tesfai). https://doi.org/10.1016/j.jaridenv.2020.104327 Received 12 June 2020; Received in revised form 9 September 2020; Accepted 24 September 2020 Available online 9 October 2020 0140-1963/© 2020 Elsevier Ltd. All rights reserved. R.T. Tesfai et al. Journal of Arid Environments 185 (2021) 104327 important populations is found on the Messir Plateau (Danakil Desert of areas and water sources. We compared data between dry periods when Eritrea) which has no protected status (Moehlman, 2002; Tesfai et al., the only available water source was the Asaila spring and wet/rainfall 2019). The Asaila spring is the only permanently available water source periods when temporary surface water was available. We expected that: for the African wild ass on the Messir Plateau during dry months (Fig. 1), and it is shared with people and livestock. (1). During dry months, all African wild ass occurring on the Messir African wild ass live in arid habitats where grass is sparse and widely Plateau would visit the Asaila spring since it is the only available dispersed. Competition between females for forage may limit their permanent water source within 9 km of the lower elevation plains ability to form long term associations (Moehlman, 2002) and the only area of the Messir Plateau. The next nearest accessible permanent stable social unit is mother and offspring. The African wild ass has a water is ‘Alad’ at distance of 30 km from the Messir Plateau to the resource defence polygynous mating system and territorial males southwest (Fig. 1). dominate an area that has resources that females require and thus they (2). Females with foals aged three months or less, and females with indirectly control access to females in estrous (Klingel, 1972; Ruben­ foals aged between 4 and 12 months, would visit water sources stein, 1994; Moehlman, 1998). more frequently than females with offspring older than twelve The local people in the study area own an estimated 600 head of months and/or non-reproductive females and males. Our livestock mainly goats, sheep, camels, domestic donkeys, and a few assumption is that water and quality forage are crucial for the cattle (Tesfai, 2006). However, the Messir Plateau is under increasing maintenance of a lactating female and her ability to provide milk pressure from cattle coming from the highlands during the rainfall for her foal (Loudon and Kay, 1984; Becker and Ginsberg, 1990). months. Competition with livestock affecting access to adequate forage (3). African wild ass would visit the Asaila spring that is near settle­ and water has been identifiedas a major threat to the African wild ass in ments and livestock only at night, while they would visit tem­ the Danakil ecosystem (Tesfai, 2006; Kebede et al., 2014; Moehlman porary water sources that occur at a distance of 9–10 km from et al., 2015, 2016). African wild ass must have access to water in order to settlements during the day. survive and lactating females with foals are expected to drink more (4). Distance travelled between foraging areas and temporary water frequently than non-lactating females. Females that have young foals of sources during rainfall months would be less than the distance less than 3 months (peak of lactation) are expected to drink even more travelled between foraging areas and the Asaila spring in the dry frequently. Hence, in this study we differentiated between female Afri­ months. We assume that temporary water sources are widely can wild ass with young foals (less than three months old) and older foals distributed during these months and that better-quality forage is (4–12 months old). We collected data on i) frequency of visits to water also more widely available in the study area. by adults in different sex and reproductive classes, ii) time of the day that they visited water, and iii) distances travelled between foraging Fig. 1. Map of the study area (Messir Plateau) showing the location of the permanent water source Asaila spring and at least six temporary water sources that occur after rainfall events, and other permanent water points in the Danakil ecosystem (Eritrea). Asaila spring is the nearest permanent water available for the African wild ass occurring on the Messir Plateau. The second closest permanent water source is ‘Alad’ at distance of 30 km to the southwest of the Messir Plateau at the bottom of the western escarpment. 2 R.T. Tesfai et al. Journal of Arid Environments 185 (2021) 104327 2. Materials and methods Table 1 Monthly rainfall on the Messir Plateau for the study period. Data obtained from 2.1. Study site CHIRPS online portal (https://earlywarning.usgs.gov/fews). Two camera traps were used at seven different water sources (one permanent and six temporary) to ◦ 0 ◦ 0 The study was conducted on the Messir Plateau (15 00 N, 40 02 E) monitor the drinking behaviour of African wild ass on Messir Plateau, Eritrea (Oct 2016–Mar 2019). in the Danakil ecosystem (Fig. 1) from October to December 2016, March to June 2017, February to April 2018 and January to March Year Rainfall Water African Method Days of 2019.