Provide supplementary water to increase reproduction/survival
Overall effectiveness category Likely to be beneficial
Number of studies: 6
Background information and definitions
In arid environments, artificial water sources may be provided to aid survival or population expansion for species of conservation concern (e.g. West et al. 2017). This may be done as part of translocation or reintroduction programmes and also for securing existing populations of threatened species.
West R., Ward M.J., Foster W.K. & Taggart D.A. (2017) Testing the potential for supplementary water to support the recovery and reintroduction of the black-footed rock-wallaby. Wildlife Research, 44, 269–279.
Supporting evidence from individual studies
A study in 1982–1999 of a large desert area in Oman (Spalton et al. 1999) found that a population of released captive-bred Arabian oryx Oryx leucoryx initially provided with supplementary water and food increased over 14 years, but then declined due to poaching. Oryx numbers in the wild peaked at >400 animals, 1–14 years after the release of 40 animals. Poachers (capturing live animals, especially females, for international trade) then removed at least 200 oryx over the next three years. Animals were taken back into captivity to re-establish a captive breeding program. Seventeen years after releases began, the captive population was 40, and approximately 104 remained in the wild, with a high male:female sex ratio. Arabian oryx became extinct in Oman in 1972. Founders for the initial captive herd were sourced from international collections. Forty individually marked oryx were released in 1982–1995. A sample of wild-born animals was individually marked to retain the marked proportion at 20–30%. The original released herd was provided with water and food for seven months after release. Population estimates were derived from sightings using mark-recapture analysis.Study and other actions tested
A controlled, before-and-after study in 2001 in five shrubland sites in Western Australia (Hardman & Moro 2006) found that most released captive-bred banded hare-wallabies Lagostrophus fasciatus and rufous hare-wallabies Lagorchestes hirsutus provided with supplementary water, along with supplementary food and predator control, survived at least two months after being released into a fenced peninsula. After 1-2 months, 10 of 16 rufous hare-wallabies and 12 of 18 banded hare-wallabies were still alive. Overall both rufous and banded hare-wallabies recaptured had similar body conditions to when they were released, although rufous hare-wallabies lost 12% of body condition while waiting for release in holding pens (data presented as a body condition index; see paper for details). Sixteen captive-bred rufous hare-wallabies and 18 captive-bred banded hare-wallabies were released at five sites in August 2001. Six rufous and nine banded-hare wallabies were placed in separate 3-ha enclosures with electrified fencing for 10–19 days before being released. Remaining animals were released directly into the wild. Supplementary water and food (kangaroo pellets, alfalfa) were made available to all hare-wallabies (those kept in holding pens and those not; duration of feeding not given). Hare-wallabies were monitored by radio tracking (once/week for 1.5 years after release) and live-trapping (at 4 and 8-9 weeks after release). Release areas were within a fenced peninsula where multiple introduced mammals were controlled or eradicated.Study and other actions tested
A replicated study in 1951–2007 in 10 desert sites in Arizona and New Mexico, USA, and the Gulf of California, Mexico (Wakeling et al. 2009) found that providing supplementary water at some sites was associated with increases in desert bighorn sheep Ovis canadensis population size. At three out of 10 sites where supplementary water was provided, it was associated with an increase in bighorn sheep populations. However, at one site, provision of water was associated with declines in sheep populations. The remaining six sites showed no association (data not presented). Data were obtained from historical records for ten sites with long-term survey and hunting information. Data included counts of bighorn sheep from both surveys and hunter harvests, and the number of watering sites provided.Study and other actions tested
A replicated study in 2009 in four agroforestry sites in Alentejo and Algarve, Portugal (Loureiro et al. 2011) found that artificial waterholes were used by European rabbits Oryctolagus cuniculus and stone martens Martes foina. European rabbits used four out of 16 artificial waterholes. At least one waterhole was used by stone martens (number of waterholes used by this species is not stated). In September and October 2009, sixteen artificial waterholes in four agroforestry estates dominated by cork Quercus suber (2–6 waterholes/estate) were monitored using camera traps. No description of the waterholes is provided. Waterholes were monitored for 7 or 14 days, using one camera trap/waterhole.Study and other actions tested
A study in 2011–2014 of a dry dwarf-scrubland site in Saudi Arabia (Islam et al. 2014) found that released captive-bred Arabian gazelles Gazella arabica initially provided with supplementary water and food after release into a fenced area started breeding in the year following the first releases. Seven females gave birth in August–September of the year after the first releases and all calves survived to at least the end of the year. Of 49 gazelles released over three years, 10 had died by the time of the final releases. In 2011–2014, three groups of captive-born gazelles, totalling 49 animals, were released in a 2,244-km2 fenced reserve. They were moved from a wildlife research centre and held for 23 days to a few months before release in enclosures measuring 500 × 500 m. Water and food was provided for three weeks following release. Released gazelles were radio-tracked from the ground and air.Study and other actions tested
A study in 2011–2014 in a semi-arid area in South Australia (West et al. 2017) found that over half of released captive-reared black-footed rock-wallabies Petrogale lateralis provided with supplementary water after being released into a large predator-free fenced area survived for at least two years and most females reproduced. Ten (five males, five females) of 16 rock-wallabies (63%) survived more than two years after being released. All five females that survived reproduced within 2–6 months of release. Over three years, 28 births from nine females were recorded. Between March 2011 and July 2012, sixteen captive-reared black-footed rock-wallabies (eight males, eight females; 1–5 years old) were released in three groups into a 97-ha fenced area. Ten of the 16 rock-wallabies were wild-born and fostered by yellow-footed rock-wallaby Petrogale xanthopus surrogate mothers in captivity. Introduced predators, common wallaroos Macropus robustus and European rabbits Oryctolagus cuniculus were removed from the enclosure. Supplementary water was provided in five 8-l tanks that were monitored with camera traps in 2011–2014. Rock-wallabies were fitted with radio-collars and tracked 1–7 times/week in 2011–2014. Trapping was carried out on seven occasions in 2011–2014.Study and other actions tested