The use of translocation as a conservation tool in the protection of dhub (Uromastyx aegyptia leptieni) against urbanisation in the Emirate of Dubai, United Arab Emirates
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Date
2023
Authors
O'Donovan, Declan
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University College Cork
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Abstract
The UAE is described as hyperarid desert environment with mean maximum temperatures reaching 43.9 °C in July and mean minimum of 12.6 °C in January. It lies between 22°30’ and 26°10’N and 51° and 56°25’E. The Emirate of Dubai, the second largest Emirate in the United Arab Emirates is a fast-evolving metropolitan city that has changed from a small trading hub in the Arabian Gulf to an economy based on tourism and the provision of novel and luxurious experiences.
Urbanisation pressures within Dubai, where almost 80% of the population now live in an urban setting, have increased dramatically over the last number of years. The resident population grew by over 173% in the 10 years to 2021 to approximately 3,478,300. To cater for residents and tourists alike, new roads, places to live and social and recreational activities have been developed and are being planned. As a result, previous areas of natural desert have been destroyed to make way for the continued development of the Emirate. It is imperative that procedures and protocols are put in place to protect the biodiversity of the affected lands.
The current study was carried out between October 2014 and December 2017 with intermittent data collection of environmental data until December 2019. The primary focus was on two sites, Wadi Al Safa (WAS - N 25.088360° and E 55.282707°) and Mugatrah (MUG - N 24.812233° and E 55.248874°) within the Emirate of Dubai. The study looked at various factors affecting the survival of the spiny tailed lizard, Uromastyx aegyptia leptieni (dhub), one of the 72 species of herpetofauna considered native to the UAE. Dhub are a diurnal, fossorial species listed on Appendix II of CITES and listed as VU on the UAE National Red List of Herpetofauna. Using dhub as a flagship species should help to raise awareness about the fragility of the desert environment, the current threats faced by the dhub and other species, and to gather vital information that could aid in potential translocation efforts.
Analysis of video data collected with CCTV cameras found that dhub are inherently a sedentary species, spending more than 80% of observed time below surface. When they did emerge, 14% of the emerged time was spent in sedentary behaviours, usually basking at the burrow or nearby on the gravel or a raised bush. The most active periods were in the spring and particularly March and April. During this time, dhub showed a unimodal burrow emergence pattern with a peak between 12:00 and 14:00. However, during the hottest months, dhub exhibited a bimodal activity pattern and usually went into their burrows between 11:00 and 13:00 before emerging and spending the majority of the time outside basking.
The orientation of burrows revealed a distinct westerly direction, in contrast to previous research on dhub in Saudi Arabia where burrows predominantly faced southwest or southeast. In Israel, no specific orientation was identified. However, in the Wadi Al Safa site, there was a notable variation in orientation between seasons. The deployment of Radio Frequency Identification (RFID) traps showed that several different dhub could enter or leave the burrow throughout the day. The mean travel distance for all dhub over the study period (recorded as being the distance the animal moved from its first capture burrow to the furthest of the RFID traps), was similar at 128.8 m (SEM 11.0) for females and 113.0 m (SEM 10.4) for males. As the ultimate goal of the current study was to develop a mitigation translocation procedure for dhub, this information will allow field workers to decide on stocking densities of dhub, the number, spacing and dimensions of artificial or natural burrows to complete the translocation.
In a desert environment, a species’ ability to use and avoid extreme temperatures is vital to its survival. Without knowing the range of temperatures, a dhub can tolerate, the ability to plan translocations is hindered. As such, the study also demonstrated, through the use of copper analogues, that the operative temperature Te (the environmental temperature range for the species) range was ± 19 °C (a low of 19 °C in Winter to a high of 38 °C in Summer). Internal burrow temperature data collected between June through to September showed the daily temperatures did not fall below 34.5 °C in June or rise above 37.5 °C.
Foraging was the most active behaviour dhub engaged in with a mean time of 9:00 minutes for males and 6:00 minutes for females. There were a confirmed 8 forage plant species (all perennials) recorded across both sites while another 12 forage species were recorded which had been confirmed from other studies as forage plants. This indicates that there were sufficient forage resources for the dhub if grazing from larger herbivores such as camels, goats and gazelle species is controlled.
The next most active behaviour was burrow cleaning with females spending less time (mean 1:35 ± SE=0:10 minutes) engaged in this than males (1:51 ± SE=0:15 minutes). Burrow cleaning was observed at some stage every day and was probably under-represented time wise in the data since the behaviour could not be observed once the dhub went sub-surface.
A major part of any translocation is health monitoring. There were differences between the 25(OH)D levels across both sites, possibly due to overgrazing and exposure times to UV-B. If human levels of Vit D were used as the reference values, then 30% (N=7) of dhub in MUG in 2015 would be considered deficient (<25 nmol/L) and the remaining 70% (N=17) would be insufficient (<75 nmol/L ) and only 40% (N=19) of dhub from WAS would be considered to have a sufficient level. Vitamin D levels were slightly better in 2016, when 74% (N=47) of dhub sampled in WAS would be considered sufficient or higher, while 71% (N=21) of dhub in MUG would have been considered to have insufficient levels of Vit D3. Further studies on the correct levels of 25(OH)D in dhub blood need to be investigated especially as many reference intervals used in veterinary practice are determined from captive animals and may not reflect the wild situation.
This study has shown how dhub can be successfully translocated if required. The study has also demonstrated what the consequences for the dub are if it is not done correctly. While large-scale translocations are theoretically feasible, careful consideration of various factors and insights gained from this study, such as dhub behaviour, potential travel distances, burrow orientation, vegetation needs for food and shelter, and health monitoring, is crucial. This comprehensive approach is essential to guarantee the success of any translocation project and subsequent enforced protection measures.
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Keywords
Uromastyx , Translocation , Vitamin D , UAE Urbainsation
Citation
O'Donovan, D. 2023. The use of translocation as a conservation tool in the protection of dhub (Uromastyx aegyptia leptieni) against urbanisation in the Emirate of Dubai, United Arab Emirates. PhD Thesis, University College Cork.