Terrestrial Reptiles and Amphibians of the United Arab Emirates

Abstract

Among the diverse habitats of the United Arab Emirates (UAE), 60 terrestrial reptiles and 2 amphibian species have been recorded, of which 1 is endemic to the country, 59 are native and 3 are introduced. The highest diversity is in the northeast of the country and the highest level of endemism is within the Hajar Mountains which are shared between Oman and UAE. The only UAE endemic vertebrate is the Emirati Leaf-toed Gecko, which along with 13 other reptile species is endemic to Hajar Mountains (Oman and UAE). Despite development being considered as the largest threat to terrestrial reptiles and over utilization of surface freshwater for amphibians, many of the widespread species have benefited from the protection provided by the protected areas distributed across the country. Species with restricted or fragmented distribution ranges require additional conservation efforts.

1 Diversity and Distribution of Terrestrial Reptiles

With an estimated 11,940 reptile species globally (Uetz 2022), the Arabian Peninsula is home to 178 described species (Cox et al. 2012; Šmíd et al. 2021a, b). Within the UAE, 60 species of terrestrial reptiles have been recorded of which 57 are native, 3 introduced (alien species) and 1 is endemic to the country (Burriel-Carranza et al. 2019). Reptiles can be found in all habitat types of the UAE, with the highest diversity in the northeast of the country (Fig. 16.1). The Hajar Mountains in the UAE have 14 endemic species whose extent of occurrence is restricted to this mountain range that is shared between Oman and the UAE (Burriel-Carranza et al. 2022). Reptile species from the UAE are in the Order Squamata and comprise 14 families, including the Agamas (Agamidae), Typical Geckos (Gekkonidae), Leaf-toed Geckos (Phyllodactylidae), Semaphore Geckos (Sphaerodactylidae), Lizards (Lacertidae), Desert Worm Lizards (Trogonophidae), Skinks (Scincidae), Varanids (Varanidae), Boas (Boidae), Colubrid Snakes (Colubridae), Sand Snakes (Psammophiidae), Thread Snakes (Leptotyphlopidae), Blind Snakes (Typhlopidae), and Vipers (Viperidae). The agamas have six species from four genera, Typical Geckos eleven species from seven genera, Leaf-toed Geckos six species from two genera, Semaphore Geckos five species from two genera, Lizards ten species from three genera, Skinks six species from five genera, Colubrid Snakes five species from four genera, Sand Snakes two species from two genera and Vipers four species from three genera. The families of Desert Worm Lizards, Varanids, Boas, Thread Snakes and Blind Snakes are comprised of one species each. All of the terrestrial reptile species within the UAE are harmless with the exception of the four venomous snakes, all vipers, which are of medical importance (Russell and Campbell 2015; Burriel-Carranza et al. 2019).

Fig. 16.1

UAE terrestrial reptile species richness by 10 arc-minutes grid cells inferred with occurrence point data Map source: Modified from Burriel-Carranza et al. (2019), reproduced under Creative Commons license (CC BY-SA-4.0)

1.1 Agamas

There are six species from the family Agamidae in the UAE. All of the agama species are diurnal and occupy a wide range of habitats from coastal deserts, through the sandy interior deserts to the rocky Hajar Mountains and their surrounding gravel plains. They range in body size from 6–50 cm, from the small Toad-headed Agamas to the large and bulky Spiny-tailed Lizards. The Arabian Toad-headed Agama (Phrynocephalus arabicus) and Long-tailed Toad-head Agama (Phrynocephalus longicaudatus) are widely distributed in the arid areas of the UAE along both the coastal and inland deserts up to 300 m in elevation (Gardner 2013; Burriel-Carranza et al. 2019). Arabian Toad-headed Agamas (Fig. 16.2a) prefer habitats with soft desert sand and, as a defense mechanism, they will vibrate the body into the sand to conceal it from sight. Long-tailed Toad-headed Agamas are found in habitats with more compact soil types in comparison with the Arabian Toad-headed Agamas, and rely on camouflage to avoid potential threats. Both species of Toad-headed Agamas have no external ear openings, the nostrils are positioned upwards and the eyes are encircled with large scales which function as a shield against the sand. Both species of Toad-headed Agamas feed on small insects and will lay 2–3 eggs per clutch during the summer.

Fig. 16.2

(a) Arabian Toad-headed Agama; (b) Leptien’s Spiny-tailed Lizard. Photo credit: Johannes Els (a, b)

The larger Yellow-spotted Agama (Trapelus flavimaculatus) is an Arabian endemic with a wide distribution across Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, UAE and Yemen (Sindaco and Jeremčenko 2008; Gardner 2013; Burriel-Carranza et al. 2019; Carranza et al. 2018, 2021). Yellow-spotted Agamas are less specialized than the Toad-head Agamas and occupy a variety of habitat types from the coast to inland sandy and gravel plains up to 400 m in elevation (Burriel-Carranza et al. 2019). Adults are brightly colored especially males with a blue head, throat and body covered in white spots and the tail is orange with dark bands. Contrasting to the adults, the hatchlings and juveniles are brown with white spots which most likely aid in camouflage from predators. Yellow-spotted Agamas feed on insects and other arthropods.

Among this group of agamas, the largest and bulkiest are the two subspecies of Spiny-tailed Lizards (Uromastyx aegyptia), known locally as ‘dhub’, which have non-overlapping distributions (allopatric) and have different ecological preferences. Both of these subspecies can be found in bare areas with sand, but the Leptien’s Spiny-tailed Lizard (Uromastyx aegyptia leptieni) is restricted to the northeast of the country from sea level up to 400 m in elevation in areas where annual precipitation is higher, while the Small-scaled Spiny-tailed Lizard (Uromastyx aegyptia microlepis) lives in the southwest of the country from sea level up to 200 m, tolerates higher temperatures, and lives in more arid areas (Burriel-Carranza et al. 2019). An Arabian endemic, Leptien’s Spiny-tailed Lizard (Fig. 16.2b) is distributed across the northeastern UAE, parts of the Hajar Mountains and the Batinah Plain in Oman (Gardner 2013; Burriel-Carranza et al. 2019, 2022; Carranza et al. 2018, 2021). The Small-scaled Spiny-tailed Lizard has a wide distribution across Arabia into Iraq, Jordan, Syria and coastal Iran (Gardner 2013; Sindaco and Jeremčenko 2008). Both subspecies of Spiny-tailed Lizard are herbivorous, feeding on a variety of plant species, but young individuals may consume invertebrates. Spiny-tailed Lizards have a thick tail covered with hard spiny scales which provide some protection from predators.

A rock habitat specialist, the Hajar Rock Agama (Pseudotrapelus jensvindumi) is restricted to the Hajar Mountains and surrounding gravel plains from sea level up to 1000 m in elevation in the UAE (Burriel-Carranza et al. 2019). This species is endemic to the Hajar Mountains which are shared between Oman and UAE, from Ras Al Hadd in the southeast of Oman to the Musandam Peninsula in the north (Tamar et al. 2016a, b, 2019; Carranza et al. 2021). Hajar Rock Agamas are abundant throughout their range, and both males and females are territorial. During the breeding season, mature males have a distinctive blue head and body, while the females have a brownish body with several orange or red spots. Hajar Rock Agamas feed on insects and can be active during the hottest periods of the day; when the surface of the rocks is too warm they will use their long thin legs to elevate the body off the surface to cool down, and if that fails they will retreat into the shade of rock crevices.

1.2 Geckos

Geckos in the UAE are the most diverse group of terrestrial reptiles, with 21 species from three families: Typical Geckos (Gekkonidae), Leaf-toed Geckos (Phyllodactylidae) and Semaphore Geckos (Sphaerodactylidae). All of the species are nocturnal with the exception of the Semaphore Geckos (Pristurus) which are mainly diurnal or both diurnal and nocturnal. Gecko species range in body size from the Small Semaphore Gecko (Pristurus minimus) of 3 cm to the large and robust 11-cm Wonder Gecko (Teratoscincus keyserlingii). Geckos are found throughout the UAE in both natural and man-made habitats (anthropogenic). The Baluch Ground Gecko (Bunopus tuberculatus), Rough Bent-toed Gecko (Cyrtopodion scabrum), Persian Gecko (Hemidactylus persicus), Red Sea House Gecko (Hemidactylus robustus), Arabian Web-footed Sand Gecko (Trigonodactylus arabicus), Dune Sand Gecko (Stenodactylus doriae), Eastern Sand Gecko (Stenodactylus leptocosymbotes) and Slevin’s Sand Gecko (Stenodactylus slevini) are widespread in arid desert areas from sea level to 400 m in elevation (Gardner 2013; Burriel-Carranza et al. 2019). Yellow-bellied House Geckos (Hemidactylus flaviviridis) are an introduced (alien) species which is confined to urban areas and is widely distributed throughout the UAE (Burriel-Carranza et al. 2019), with its distribution expanding along with urban development (see Chap. 23). Rough Bent-toed Geckos (Cyrtopodion scabrum) and Red Sea House Geckos (Hemidactylus robustus) are also often associated with man-made habitats, where they can be more abundant than in their natural habitats.

The Hajar Banded Ground Gecko (Trachydactylus hajarensis), Leaf-toed Geckos (Asaccus), Fan-footed Geckos (Ptyodactylus) and Semaphore Geckos (Pristurus) are found at higher elevations with more precipitation in a wide spectrum of habitats, from vegetated to bare areas with gravel rock (Burriel-Carranza et al. 2019). The exception is the Small Semaphore Gecko (Pristurus minimus), which occupies both vegetated sandy and gravel rock habitats from sea level to 300 m in elevation (Gardner 2013; Burriel-Carranza et al. 2019). Rock Semaphore Geckos (Pristurus rupestris) and other members of this group are naturally found in the Hajar Mountains (Garcia-Porta et al. 2017), but the distribution of the Rock Semaphore Gecko has expanded beyond its natural range due to human intervention and they have colonized several coastal and inland urban areas over the last few decades (Burriel-Carranza et al. 2019).

Geckos in the UAE from the family Gekkonidae include the Baluch Ground Gecko (Bunopus tuberculatus), Rough Bent-toed Gecko (Cyrtopodion scabrum),Yellow-bellied House Gecko (Hemidactylus flaviviridis), Persian Gecko (Hemidactylus persicus), Red Sea House Gecko (Hemidactylus robustus), Gulf Sand Gecko (Pseudoceramodactylus khobarensis), Arabian Web-footed Sand Gecko (Trigonodactylus arabicus), Dune Sand Gecko (Stenodactylus doriae), Eastern Sand Gecko (Stenodactylus leptocosymbotes), Slevin’s Sand Gecko (Stenodactylus slevini) and Hajar Banded Ground Gecko (Trachydactylus hajarensis).

The Baluch Ground Gecko, Rough Bent-toed Gecko, Dune Sand Gecko, Eastern Sand Gecko, Slevin’s Sand Gecko and the Hajar Banded Ground Gecko are all ground-living species with slender toes without toepads. Most of the species are found in sandy habitats, with the exception of the Eastern Sand Gecko, which prefers compact soil types such as interdune gravel plain and those bordering the Hajar Mountains. Gulf Sand Geckos are found on moist, salt-impregnated to solid, salt-encrusted flats (sabkhas) and are often the only reptile species occupying such habitats (Gardner 2013; Metallinou et al. 2014; Carranza et al. 2018, 2021). To aid mobility in these moist and salt-encrusted habitats, the species is slender in comparison with the Dune Sand Gecko, and has long thin legs with 10–15 rows of sharply pointed scales beneath the toes. Endemic to the Hajar Mountains of Oman and UAE, the Hajar Banded Ground Gecko occupies rocky habitats with or without vegetation (de Pous et al. 2016a, b; Burriel-Carranza et al. 2019). All the other species in the UAE from this family are widely distributed across Arabia and are abundant within suitable habitats. The toes of the Yellow-bellied House Gecko, Persian Gecko and Red Sea House Gecko have adhesive pads (lamellae) which facilitate surface traction and enable them to climb; thus, they are not restricted within their habitats to the ground for sourcing food or reproduction, which can be beneficial for their survival. The smallest species in this family of geckos is the Arabian Web-footed Sand Gecko (Fig. 16.3a) which is widely distributed across the country, throughout most of Arabia and into Jordan (Pola et al. 2021), in soft sandy areas with dunes and scattered vegetation. Well adapted to its environment this small and slender gecko has webbing between its fingers on the forelimbs and fringes of pointed scales beneath toes of the hindlimbs which allows it to move with ease on the soft sand.

Fig. 16.3

(a) Arabian Web-footed Sand Gecko, illustrating the webbing between the toes of this sand dweller; (b) Emirati Leaf-toed Gecko, the only endemic vertebrate of the UAE. Photo credit: Johannes Els (a, b)

The gecko family Phyllodactylidae in the UAE consist of six species with restricted distribution ranges and all of which are endemic to the Hajar Mountains of the UAE and Oman. This family includes the Leaf-toed Geckos (Asaccus), which have a pair of adhesive toe pads on each toe, and Fan-footed Geckos (Ptyodactylus) with a fan of numerous lamellae, and all are agile climbers moving with ease in rocky habitats. Females of the Leaf-toed Geckos have only one oviduct, and therefore always lay a single egg, although they can produce several eggs throughout the year. Fan-footed Geckos lay two eggs and communal nesting between individuals at the same location over a period of time is not uncommon. Both Leaf-toed Geckos and Fan-footed Geckos are nocturnal, but Fan-footed Geckos may also be encountered during the day in the shade of rock crevices. They feed on a variety of insect and other arthropod species.

The Emirati Leaf-toed Gecko (Asaccus caudivolvulus), Gallagher’s Leaf-toed Gecko (Asaccus gallagheri), Gardner’s Leaf-toed Gecko (Asaccus gardneri), Margarita’s Leaf-toed Gecko (Asaccus margaritae), Orlov’s Fan-footed Gecko (Ptyodactylus orlovi) and the Ruusaljibal Fan-footed Gecko (Ptyodactylus ruusaljibalicus) are all species within the family Phyllodactylidae. The only endemic vertebrate of the UAE is the Emirati Leaf-toed Gecko (Fig. 16.3b), which is found in isolated and fragmented coastal rocky habitats along the east coast at low elevations (Carranza et al. 2016; Burriel-Carranza et al. 2019; Carranza and Els 2021). This species is distinguished from all other Leaf-toed Geckos by the presence of tubercles on the upper arms. Gardner’s Leaf-toed Gecko is widely distributed in the northern Hajar Mountains from around Harf Ghabi in the Musandam Peninsula, Oman, and further south into the UAE where it is frequently found at elevations between 100 and 600 m (Carranza et al. 2016; Burriel-Carranza et al. 2019). Margarita’s Leaf-toed Gecko has isolated populations throughout the northern Hajar Mountains in the Musandam Peninsula, Oman, and further south to Wadi Al Helo in the UAE (Carranza et al. 2016; Burriel-Carranza et al. 2019). Further studies are required into the distribution of this species, but within the UAE it is known from lower elevation in the interior of mountains, and in the Musandam Peninsula it has been found at higher elevation between 1400 and 1500 m (Carranza et al. 2021). In all three species, (Emirati Leaf-toed Gecko, Gardner’s Leaf-toed Gecko, Margarita’s Leaf-toed Gecko), the tail can be coiled and tip is laterally flattened and expanded vertically, and may be used to signal between individuals as a form of territorial display. Gallagher’s Leaf-toed Gecko is the smallest species among the Leaf-toed Geckos, and these geckos are abundant and widespread throughout the Hajar Mountains, from Jebel Akhdar in Oman and further north through the UAE into the Musandam Peninsula (Carranza et al. 2018, 2021; Simó-Riudalbas et al. 2018). In the UAE, the Gallagher’s Leaf-toed Geckos are found from sea level up to around 600 m in elevation (Burriel-Carranza et al. 2019). Gallagher’s Leaf-toed Geckos is the only species of Leaf-toed Gecko in the UAE where there are visible differences between the males and females; males have a bright yellow tail with dark bands in comparison with white barred with black in females.

Orlov’s Fan-footed Gecko is endemic to the Hajar Mountains of Oman and the UAE, but is absent from the Musandam mountains. In the UAE the species is found from sea level up to 1000 m in elevation. Ruusaljibal Fan-footed Gecko is endemic to the carbonate mountains of the Musandam Peninsula (Ruus Al Jibal) in Oman and its distribution extends south into the UAE towards Dibba (Simó-Riudalbas et al. 2017; Carranza et al. 2021). Within the UAE, the species has a limited distribution range and is frequently encountered from sea level up to 800 m in elevation (Burriel-Carranza et al. 2019). Orlov’s Fan-footed Gecko and the Ruusaljibal Fan-footed Gecko are good examples of cryptic species (species morphologically very similar) well-differentiated genetically and geographically (present separated distributions).

The geckos of the family Sphaerodactylidae are the Carter’s Semaphore Gecko (Pristurus carteri), Bar-tailed Semaphore Gecko (Pristurus celerrimus), Small Semaphore Gecko (Pristurus minimus), Rock Semaphore Gecko (Pristurus rupestris) and the Wonder Gecko (Teratoscincus keyserlingii). All of the species from this family within the UAE are diurnal, except for the Wonder Gecko which is strictly nocturnal, and are predominantly ground-dwelling with adhesive pads absent on the toes. As suggested by the name semaphore, these geckos use their tails as a form of visual communication between individuals of their own species by curling and waving it. Carter’s Semaphore Geckos in the UAE are rarely encountered, and are restricted to a very small geographical area near the foothills of Jebel Hafeet which is divided by the political borders of Oman and UAE (Gardner 2013). The occurrence of the species in the UAE is considered the most northern distribution for this southern Arabian endemic, which is abundant and widely distributed in Oman with isolated populations in Yemen (Sindaco and Jeremčenko 2008; Carranza et al. 2021). Bar-tailed Semaphore Geckos are endemic to the Hajar Mountains, where their distribution extends from Jebel Akhdar, Oman, north through the UAE and into the Musandam Peninsula (Gardner 2013; Carranza et al. 2021; Burriel-Carranza et al. 2022). In the UAE the species is abundant throughout the Hajar Mountains and encountered from sea level up to 1400 m in elevation (Burriel-Carranza et al. 2019). Rock Semaphore Geckos (Fig. 16.4a) are widely distributed through the Hajar Mountains and surrounding lowland areas in Oman and UAE, with populations also on the southern coast of Iran (Garcia-Porta et al. 2017). Within the UAE, the distribution of the Rock Semaphore Geckos extends from the Hajar Mountains inland and along the Arabian Gulf coastline, including some of the offshore islands. It is abundant in both its natural rocky habitats within the Hajar Mountains, and in urban areas where it has colonized successfully. Rock Semaphore Geckos are encountered from sea level up to 1300 m in elevation (Burriel-Carranza et al. 2019).

Fig. 16.4

(a) Rock Semaphore Gecko; (b) Wonder Gecko. Photo credit: Johannes Els (a, b)

The only Semaphore Gecko from the UAE which is absent from the Hajar Mountains is the Small Semaphore Gecko, which is found inland in sandy habitats with vegetation. Small Semaphore Geckos are less frequently encountered and are known to occur from sea level to up to 300 m in elevation (Burriel-Carranza et al. 2019). Its distribution extends from the UAE into Oman, Saudi Arabia and into eastern Yemen (Sindaco and Jeremčenko 2008; Carranza et al. 2021; Al Mutairi et al. 2023). Semaphore Geckos lay a single hard-shelled egg, with the exception of the much larger Carter’s Semaphore Gecko which lays two eggs, and all species will reproduce multiple times throughout the year.

The largest species of the family Sphaerodactylidae is the Wonder Gecko (Fig. 16.4b), which is nocturnal and ground-dwelling, and within Arabia is known only from the UAE (Gardner 2013; Els et al. 2019a, b; Tamar et al. 2021). Wonder Geckos from the UAE are genetically similar to those populations found in coastal Iran from where the species distribution range extends further into Afghanistan and Pakistan (Tamar et al. 2021). Within the UAE, Wonder Geckos occur as isolated and severely fragmented populations due to urban development from Abu Dhabi northwards to Umm Al Quwain and inland towards Al Dhaid; they occur from sea level up to 200 m in elevation (Soorae et al. 2018; Burriel-Carranza et al. 2019; Els et al. 2019a, b). Wonder Geckos have been found in habitats with both sandy and compact soils with vegetation. It is a solitary species which takes refuge during the day in burrows. Females lay one or two large round eggs throughout the year. Wonder Geckos, as adults, are brightly colored, but as hatchlings and young animals are blackish with a less distinctive ground-color which may appear less conspicuous to predators and contribute to their survival.

1.3 Lizards

There are 11 species of lizards in the UAE, 10 species from the family Lacertidae and one species of desert worm lizards (family: Trogonophidae); the Zarudnyi’s Worm Lizard (Diplometopon zarudnyi). The family Lacertidae include six species of Fringe-toed Lizards (Acanthodactylus), two species of Sand Lizards (Mesalina) and two species from the endemic genus Omanosaura. The Zarudnyi’s Worm Lizard is widely distributed from sea level to 300 m in elevation through the interior dry and sandy deserts (Burriel-Carranza et al. 2019). In the UAE, Fringe-toed Lizard and Sand Lizard species are widely distributed in the dry deserts with sparse vegetation below elevation of 400 m. The Hajar Blue-tailed Lizard (Omanosaura cyanura) and Jayakar’s Lizard (Omanosaura jayakari) are restricted to rocky habitats which are vegetated or poorly vegetated within the Hajar Mountains between 300 and 1200 m in elevation (Gardner 2013; Burriel-Carranza et al. 2019, 2022). In comparison with the Fringe-toed Lizards and Sand Lizards, both the Hajar Blue-tailed Lizard and Jayakar’s Lizard occur in habitats that are cooler and wetter. All these lizard species are diurnal and ground-dwelling with females laying several eggs per clutch.

In the UAE, Blanford’s Fringe-toed Lizard (Acanthodactylus blanfordii) is restricted to a small coastal habitat in Khor Kalba from sea level up to a 100 m in elevation (Burriel-Carranza et al. 2019). In Arabia, the species distribution extents from Khor Kalba in the UAE, south to Oman along the Batinah Plain around Muscat (Carranza et al. 2018, 2021). The species also occurs outside Arabia in Pakistan, southern Afghanistan and southeastern Iran (Sindaco and Jeremčenko 2008). Along the interior gravel plains on the southern slopes of the Hajar Mountains, Bosc’s Fringe-toed Lizard (Acanthodactylus boskianus) occurs from 200 to 400 m in elevation in the UAE, and its distribution extends into Oman (Gardner 2013; Burriel-Carranza et al. 2019; Carranza et al. 2021). Bosc’s Fringe-toed Lizards are found throughout Arabia, the Middle East into southwestern Iran and across most of North Africa (Sindaco and Jeremčenko 2008; Tamar et al. 2016a, b). Within the sandy interior habitats of the UAE, Saudi Fringe-toed Lizard (Acanthodactylus gongrorhynchatus) is widely distributed in scattered populations from the border of Saudi Arabia across to Abu Dhabi and Al Ain towards Dubai. Within the UAE, the Saudi Fringe-toed Lizard occur from sea level up to 400 m in elevation (Burriel-Carranza et al. 2019). It is an Arabian endemic, and the species distribution is only known from eastern Saudi Arabia and the UAE (Sindaco and Jeremčenko 2008). Haas’s Fringe-toed Lizard (Acanthodactylus haasi) and the Snake-tailed Fringe-toed Lizard (Acanthodactylus opheodurus) are rare in the UAE, with very limited information available on their natural history and their extent of distribution is uncertain (Gardner 2013; Burriel-Carranza et al. 2019; Carranza et al. 2018, 2021). Haas’s Fringe-toed Lizard is endemic to Arabia, and the Snake-tailed Fringe-toed Lizard is widely distributed across Arabia into Israel, Jordan and Iraq. The most abundant and widely distributed Fringe-toed Lizard in the UAE is Schmidt’s Fringe-toed Lizard (Acanthodactylus schmidti), which occurs in almost all dry sandy habitats of the UAE. The species is not restricted to Arabia and the distribution extends into Jordan, southeast Iraq and southwestern Iran (Sindaco and Jeremčenko 2008). All of the Fringe-toed Lizards are distinguished from Sand Lizards by the presence of lateral fringes (a series of thin comb like scales) on the hind toes.

The Hadramaut Sand Lizard (Mesalina adramitana) is endemic to Arabia and is widely distributed across the UAE in sandy deserts and gravel plains, from sea level up to 400 m in elevation (Burriel-Carranza et al. 2019). The Short-snouted Sand Lizard (Mesalina brevirostris) is widely distributed within the UAE, but restricted to coastal habitats from sea level up to 200 m in elevation (Gardner 2013; Burriel-Carranza et al. 2019). Apart from the UAE, the species’ distribution range extends across southeastern Saudi Arabia, Qatar, Kuwait into southwestern Iran (Šmíd et al. 2017).

Both the Hajar Blue-tailed Lizard (Omanosaura cyanura) and Jayakar’s Lizard (Omanosaura jayakari) are endemic to the Hajar Mountains of Oman and UAE (Gardner 2013; Burriel-Carranza et al. 2019, 2022; Carranza et al. 2018, 2021). Recent genetic studies have shown that the Hajar Blue-tailed Lizards from the UAE and the Musandam Peninsula are very distinct from all the other populations, which suggests that they may represent a new cryptic species (Mendes et al. 2018). Jayakar’s Lizards (Fig. 16.5a) are the largest species in the family Lacertidae in the UAE, with a body length of up to 20 cm. They feed mainly on insects, but Jayakar’s Lizards are known to consume plant material and thus possibly aid seed dispersal.

Fig. 16.5

(a) Jayakar’s Lizard, one of two species from the Hajar Mountains’ of the endemic genus Omanosaura; (b) Zarudnyi’s Worm Lizard, the only amphisbaenid species in the UAE. Photo credit: Johannes Els (a, b)

The only amphisbaenid (a leg-less lizard) of the UAE is Zarudnyi’s Worm Lizard (Diplometopon zarudnyi), a fossorial species which almost exclusively lives in soft sand, where they will surface at night for feeding or in search of a mate for breeding. Very little is known about the natural history of this relatively abundant species, which is distributed across the dry sandy desert habitats of the UAE. The species is widely distributed across Arabia, but absent from Yemen, and further northeast into Iraq and western Iran (Sindaco and Jeremčenko 2008; Gardner 2013; Burriel-Carranza et al. 2019; Carranza et al. 2021). Zarudnyi’s Worm Lizards are adapted to their fossorial lifestyle with their undeveloped eyes protected beneath a colorless scale, and with an absence of external ear openings (Fig. 16.5b).

1.4 Skinks

There are six species of skinks from the family Scincidae: Asian Snake-eyed Skink (Ablepharus pannonicus), Ocellated Skink (Chalcides ocellatus ocellatus), Southern Grass Skink (Heremites septemtaeniatus), Arabian Sand Fish (Scincus mitranus), Blanford’s Sand Skink (Scincus conirostris) and Tessellated Skink (Trachylepis tessellata). All of the UAE skink species are ground-dwelling and mainly diurnal, but during hot summer months it is not uncommon for them to exhibit activity for short periods after dusk. Asian Snake-eyed skink, Arabian Sand Skink and Tessellated skink lay small clutches of eggs (oviparous). Ocellated Skink (Fig. 16.6a) and Southern Grass Skink give birth to their young (viviparous). The Asian Snake-eyed Skink and Tessellated Skink are found in habitats with sparse vegetation and gravel rocks, from sea level to up a 1000 m in elevation in the Hajar Mountains (Gardner 2013; Burriel-Carranza et al. 2019). Endemic to southern Arabia, the distribution of the Tessellated Skink extends from the UAE across to Oman and into Yemen (Gardner 2013; Carranza et al. 2021). Ocellated Skinks are not native to the UAE and were introduced, presumably through activities related to horticulture; the origin of the Southern Grass Skink is questionable (Burriel-Carranza et al. 2019). Both species are associated with urban landscapes where the Ocellated Skink can be particularly abundant.

Fig. 16.6

(a) Ocellated Skink; (b) Blanford’s Sand Skink. Photo credit: Johannes Els (a, b)

Abundant and widespread, the Arabian Sand Skink is found in dry sandy deserts at elevations below 400 m (Burriel-Carranza et al. 2019). The Arabian Sand Skink is endemic to Arabia, with its distribution range extending outside the UAE into Oman, Yemen, Saudi Arabia, Qatar, Kuwait and Bahrain (Šmíd et al. 2021a, b). Blanford’s Sand Skink (Fig. 16.6b) is less abundant and prefers compact soils or gravel rock with sparse vegetation. Within the UAE, Blanford’s Sand Skink is found along the Gulf of Oman coastline in Khor Fakkan and within several localities along the Arabian Gulf coastline, including on Sir Bani Yas Island (Gardner 2013; Burriel-Carranza et al. 2019). Blanford’s Sand Skinks were also recorded along the gravel plains bordering the Hajar Mountains with an increase in abundance from Al Dhaid southwards to Jebel Buhais. Due to their ability to dive into the sand and move with little effort, both species are collectively known as ‘Sand Fish’.

1.5 Varanids

The Desert Monitor (Varanus griseus) is the only varanid species that occurs in the UAE, and it is widely distributed across most parts of the country in dry desert habitats below 300 m in elevation and where the annual precipitation is below 200 mm (Burriel-Carranza et al. 2019). The Desert Monitor (Fig. 16.7) is the largest lizard in the UAE with a body length of 56 cm with the tail up to 1.6 times longer than the body. A diurnal species which is mostly ground-dwelling, they can climb trees with ease using their powerful limbs and claws. They have a long-forked tongue which is used to detect prey, good vision and with the nostrils directed backwards towards the eyes. Desert Monitors are widely distributed across Arabia, through the Middle East and into North Africa, Central Asia and northern India (Geniez et al. 2004; Sindaco and Jeremčenko 2008; Gardner 2013). Arabia has two species of Varanids, the second being the endemic Yemen Monitor (Varanus yemenensis) from in southwestern Saudi Arabia and Yemen. Both species are taxonomically grouped within the Superfamily Anguimorpha and the family Varanidae.

Fig. 16.7

Desert Monitor. Photo credit: Johannes Els

1.6 Snakes

Within the UAE, snakes from the Suborder Serpentes are represented by 13 native species from 5 families, together with a single introduced species. These 14 species occupy a variety of habitats, but a few are specialists restricted to specific habitat types. The Arabian Sand Boa (Eryx jayakari), Crowned Leaf-nosed Snake (Lytorhynchus diadema) and Arabian Horned Viper (Cerastes gasperettii gasperettii) are adapted to live in sandy deserts and occupy areas with low annual rainfall. Others like the Hajar Saw-scaled Viper (Echis omanensis), Persian Horned Viper (Pseudocerastes persicus), Arabian Cat Snake (Telescopus dhara) and Wadi Racer (Platyceps rhodorachis) are restricted to the northeast of the country, including the Hajar Mountains, where they occupy rocky habitats with cooler temperatures and higher annual rainfall, and occur from sea level up to 1200 m. Hardwick’s Racer (Platyceps ventromaculatus) is restricted to coastal areas on the offshore islands of the UAE. The introduced Brahminy Blind Snake (Indotyphlops braminus), is found only within urban areas. Schokari Sand Racer (Psammophis schokari) is a generalist that occupies coastal, interior sandy deserts and rocky mountain habitats.

Boas from the family Boidae are represented by two species in Arabia, the Arabian Sand Boa (Eryx jayakari) and Javelin Sand Boa (Eryx jaculus), but the former is the only species found within the UAE. The Arabian Sand Boa (Fig. 16.8a) is a small nocturnal and fossorial species reaching lengths of up to 62 cm. The nostrils and eyes of this fossorial species are positioned upwards, exposing only the eyes when in ambush. Arabian Sand Boas feed mainly on geckos and rodents, but are opportunistic and will predate on small birds feeding on the ground. Females lay a small clutch of eggs. It is widespread across the country from sea level up to 300 m in elevation in dry coastal and interior sandy desert habitats (Gardner 2013; Burriel-Carranza et al. 2019). Apart from the UAE, the distribution of the Arabian Sand Boa extends into Oman, Yemen, Saudi Arabia, Bahrain, Kuwait, and into southwest Khuzestan, Iran (Sindaco et al. 2013; Carranza et al. 2021).

Fig. 16.8

(a) Arabian Sand Boa; (b) Schokari Sand Racer; (c) Hajar Saw-scaled Viper. Photo credit: Johannes Els (a–c)

The most species diverse group of snakes are within the family Colubridae, which includes the Crowned Leaf-nosed Snake (Lytorhynchus diadema), Wadi Racer (Platyceps rhodorachis), Hardwick’s Racer (Platyceps ventromaculatus), Clifford’s Diadem Snake (Spalerosophis diadema cliffordii) and Arabian Cat Snake (Telescopus dhara). Crowned-Leaf-nosed Snakes are abundant and widely distributed across the UAE in dry sandy deserts from sea level up to 300 m in elevation (Burriel-Carranza et al. 2019). In Arabia, the species is widely distributed with its distribution extending westwards throughout North Africa and eastwards to South and southwestern Iran (Sindaco et al. 2013; Carranza et al. 2021). It is a small, nocturnal and fossorial snake species that feeds mainly on geckos.

Wadi Racers are found throughout the Hajar Mountains, including the surrounding gravel plains from sea level up to 1200 m in elevation (Gardner 2013; Burriel-Carranza et al. 2019). A widely distributed species, its distribution range extends beyond Arabia into North Africa and Central Asia (Sindaco et al. 2013). It is a long and slender diurnal species, which feeds mainly on lizards, toads and fish, but as an opportunistic hunter, rodents and small birds are also taken. Hardwick’s Racers were recorded only from the two small offshore islands located in the Arabian Gulf, Sir Bani Yas and Dalma (Gardner 2013). There are no records of the species on the mainland, although its distribution extends across Saudi Arabia, Bahrain, Kuwait, Iraq and Iran along the Arabian Gulf; and also known from Jordan, North India, Pakistan, Afghanistan and southeast Turkey (Whitaker and Captian 2007; Sindaco et al. 2013; Geniez 2018).

The largest member of this family is Clifford’s Diadem Snake, a harmless species which is both diurnal and nocturnal. It occurs from sea level up to 500 m in elevation along the southern slopes of the Hajar Mountains and adjacent gravel plains, extending into sandy areas with compact soil (Gardner 2013; Burriel-Carranza et al. 2019). Widespread across Arabia, the species range extends into North Africa and into northwestern Iran. Within the UAE the species is frequently encountered around farms and cultivated areas where it preys on rodents and birds. A nocturnal species, the Arabian Cat Snake is found in rocky habitats at lower elevation throughout the Hajar Mountains, where it is less abundant in comparison with other areas of its distribution within Arabia (Gardner et al. 2010; Gardner 2013; Burriel-Carranza et al. 2019; Carranza et al. 2021). Within Arabia the species is recorded from Oman, Yemen and Saudi Arabia; and northwards into western Jordan, Israel, Palestine and the Sinai Peninsula, Egypt. With a flat head, this species can climb and access rock crevices with ease to hunt geckos and lizards. Arabian Cat Snakes have rear grooved fangs and venom is injected while chewing on the prey. It is not considered dangerous to humans.

Both habitat generalists, the two species from the family Psammophiidae are the Schokari Sand Racer (Psammophis schokari) and Moila Snake (Malpolon moilensis). Schokari Sand Racers are widely distributed across the UAE from sea level up to 1000 m in elevation (Burriel-Carranza et al. 2019). Not restricted to Arabia, its distribution extends into North Africa and northwestern India (Gonçalves et al. 2018). This species occupies sandy deserts, gravel plains and rocky habitats with vegetation. Schokari Sand Racers (Fig. 16.8b) have also successfully occupied urban areas, with individuals often occupying an area for their entire life. Within these urban areas they will take advantage of the abundance of prey species such as the Ocellated Skinks, Yellow-bellied House Geckos, rodents and smaller bird species associated with human habitation. A diurnal species, Schokari Sand Racers are both ground-dwelling and arboreal (i.e. tree-dwelling), often using vegetation to thermoregulate by moving up or down within the vegetation. In the UAE, Moila Snakes were recorded from sea level up to 300 m in elevation within coastal and inland sandy deserts and the gravel plains bordering the Hajar Mountains, but the species is absent from the mountains and the Rub’ al Khali sand desert (Burriel-Carranza et al. 2019). A widespread species, it is distributed across North Africa, into Arabia and eastwards into northwestern Iran (Sindaco et al. 2013). In comparison with the diurnal Schokari Sand Racer, the Moila Snake is active at dusk during the warmer seasons. Both species have venom to paralyze prey, which through a chewing motion are injected with grooved fangs position in the rear of the mouth. They are not considered dangerous to humans.

Slender Blind Snakes from the family Leptotyphlopidae have one species, Hooked Blind Snake (Myriopholis macrorhyncha), which is native to the UAE. The Brahminy Blind Snake (Indotyphlops braminus) from the family Typhlopidae is a global invader and restricted within the UAE to urban gardens. It is unusual in that all individuals are females, reproducing parthenogenetically. Both are harmless fossorial species, burrowing in the soil to re-surface during the night. The Hooked Blind Snake occurs from sea level up to 300 m in elevation in sandy deserts, and appears to be more abundant in the northeast of the country but may have been overlooked in surveys in the drier interior of the country (Burriel-Carranza et al. 2019). It is a widespread species ranging from East Africa across the Middle East into northwest Indian (Sindaco et al. 2013). A specialized feeder, it predates on termites and their eggs, as well as larvae and pupae from other insects. Similar to the Zarudnyi’s Worm Lizard, this fossorial species has undeveloped eyes which are covered with a transparent scale.

The four species of medically important, terrestrial venomous snakes within the UAE are members of the family Viperidae. These are the Arabian Horned Viper (Cerastes gasperettii gasperettii), Sindh Saw-scaled Viper (Echis carinatus sochureki), Hajar Saw-scaled Viper (Echis omanensis) and Persian Horned Viper (Pseudocerastes persicus). All of these viper species, with the exception of the Persian Horned Viper which colonized the Hajar Mountains from Iran during the last glaciation (de Pous et al. 2016a, b), use their serrated scales on the side of the body to make a warning ‘hiss’ sound.

Arabian Horned Vipers are widely distributed across the nation in sandy habitats. Well adapted to arid environments, they also occupy areas with lower annual rainfall from which the Sindh Saw-scaled Viper is absent. It has been recorded throughout Arabia, into Jordan, Iraq and northwestern Iran (Sindaco et al. 2013; Carranza et al. 2021). The name is misleading as not all individuals of this species have a single-scale horn above each eye. The reasons why some individuals have horns and others not are still largely unknown. The Arabian Horned Viper is adapted to sandy deserts, through which it moves with ease using sidewinding movements, and it can burry itself into the sand to ambush prey such as rodents, geckos, lizards and birds. Exclusively a ground-dweller, it is a weak climber, thus the species will not be encountered higher up in vegetation. Arabian Sand Vipers are mainly nocturnal, but during the cooler season they are often active in the early mornings when they bask in the sun. Sindh Saw-scaled Vipers are found in vegetated sandy areas and gravel plains, and are particular abundant and successful colonizers of cultivated and urban gardens where they take advantage of the abundance of both prey and water. This species occurs in the northeast of the country at lower elevation with higher annual rainfall, but is absent in the Hajar Mountains (Burriel-Carranza et al. 2019, 2022). This Arabian subspecies is found only in Oman and UAE; outside of this range the species was also recorded from Iran, North India, Bangladesh, Pakistan, South Afghanistan, and Iraq (Sindaco et al. 2013). This viper is mainly active after dusk, and females give birth to 5–11 young. The young of Sindh Saw-scaled Vipers feed on invertebrates and as they mature, progress to larger prey such as geckos and rodents.

Endemic to the Hajar Mountains of Oman and UAE, the Hajar Saw-scaled Viper (Fig. 16.8c) is also known, in error, as the Oman Carpet Viper due to earlier misconception that the species distribution was restricted only to the mountains in Oman. In the UAE it is widely distributed throughout the Hajar Mountains, from sea level up to 1000 m in elevation (Burriel-Carranza et al. 2019). Within its rocky mountainous habitat this species is relatively abundant, especially around areas with permanent surface water. It is frequently encountered within the many cultivated areas found throughout its distribution range. Primarily nocturnal, it may also be seen in daylight hours during the cooler season. Hajar Saw-scaled Vipers feed on toads, which are in abundance within most of its distribution range, but being an opportunistic predator, it will also feed on lizards, rodents and birds. The Persian Horned Viper is both nocturnal and diurnal, and is found within the rocky habitats of the Hajar Mountains from sea level up to 1400 m within the UAE (Burriel-Carranza et al. 2019). In comparison with the Arabian Horned Viper, which have a single scale-horn above each eye, the Persian Horned Vipers have horns made from several scales. Variable in body color, individuals of this species matches the color of the surrounding rocks in their habitat. Unique to the Persian Horned Viper, females will lay clutches of 11–21 eggs in an advanced stage of development which hatch after 29–30 days (Phelps 2010), compared to the typical incubation period of 60–80 days in other egg laying snake species.

2 Diversity and Distribution of Amphibians

The only amphibians occurring in the UAE are the Arabian Toad (Sclerophrys arabica) and Dhofar Toad (Duttaphrynus dhufarensis) from the frog family Bufonidae (Gardner 2013; Soorae et al. 2013; Burriel-Carranza et al. 2022). Both species have restricted distribution ranges within the UAE, and are confined to the Hajar Mountains and surrounding gravel plains where surface water is available.

The Arabian Toad (Fig. 16.9) is endemic to Arabia, and is abundant throughout most of its distribution range. In areas with permanent water, the species can be found in large numbers and is active during both the day and night. Mostly nocturnal, the Dhofar Toad is well adapted to arid environments. Dhofar Toads may not be noticed during the drier seasons of the year, until the first rains when they congregate in large numbers to spawn in seasonal water bodies. During these dry periods, Dhofar Toads seek shelter deep within rock crevices or in burrows where the soil has higher moister content, and while in a state of inactivity (aestivation) their body is protected by a slimy coat to prevent dehydration. Outside of their natural distribution range, the Arabian Toad is found within agricultural areas, which have increased its distribution within the UAE. In surveys, the chytrid fungus which has caused declines in many amphibian populations globally, has not been detected in either species in the UAE (Soorae et al. 2013).

Fig. 16.9

Arabian Toad. Photo credit: Johannes Els

3 Importance of Reptiles and Amphibians in Ecosystems

Within the arid habitats of the UAE, where overall vertebrate species richness is relatively low, reptiles have adapted to these challenging environmental conditions through modifications in their physiology and behaviors. Their ability to adapt to their environment has resulted in reptiles being one of the most diverse vertebrate groups in these arid ecosystems. In addition to higher diversity, some species also have large populations, providing a vital role in the overall functioning of the ecosystem they occupy.

Semaphore Geckos, which are the most abundant terrestrial vertebrate in the Hajar Mountains, prey on small insects that may harm crops and, therefore, act as a natural source of pest control. Within urban areas, gecko species such as the Rough Bent-toed Gecko, Yellow-bellied House Gecko and Red Sea House Gecko are often noticed at night near lights preying on insects, which may also aid in controlling vector-borne diseases transmitted by mosquitos. Larger ground dwelling species, like the Dune Sand Gecko, predate grasshoppers which, depending on their abundance, can pose a threat to cultivated areas. Snakes such as the Arabian Horned Viper predate on rodent species (Fig. 16.10), aiding in controlling population numbers. Clifford’s Diadem Snakes and Sand Racers are often found within human habitation and predate on feral rodents, which in cultivated areas can cause significant damage to crops. Apart from being predators in the food-web, they are also a source of food for smaller carnivores and birds.

Fig. 16.10

Arabian Horned Viper eating a Cheesman’s Gerbil (Gerbilus cheesmani). Photo credit: Johannes Els

The importance of reptiles in desert ecosystems is often overlooked. For example, the Spiny-tailed Lizards and Jayakar’s Lizards which consume plant material and potentially contribute to seed dispersal in the absence of larger herbivores. Some studies have shown that seeds which pass through the guts of lizards had improved germination rates compared to seeds not consumed by lizards. Parasitic species also have an important function in many ecosystems, and Arabian reptiles are also hosts to these parasites (Maia et al. 2016; Tomé et al. 2021). In a recent study it was discovered that the Sindh Saw-scaled Viper is the host for the tape worm species Ophiotaenia echidis (de Chambrier et al. 2021). Amphibian species may also host parasites and be intermediate hosts in the life cycle of some parasites between the aquatic and terrestrial environment. Similar to many of the reptile species, adult Arabian Toads feed on insects, thus aiding in controlling insect populations. They are also a source of food in both the terrestrial and freshwater aquatic ecosystem as tadpoles, which are eaten by larger carnivorous aquatic invertebrates.

4 Threats and Conservation of Reptiles and Amphibians

Habitat loss and fragmentation of ranges caused by urban development is the greatest threat to UAE reptiles and amphibians, especially for species with restricted distributions. Snakes in general are affected by persecution, even though most are harmless to humans and may be beneficial in controlling pest species. Amphibian species, although abundant and adapted to arid environments, are affected in parts of their range by the over-utilization of freshwater by agriculture, which may disrupt their reproductive cycles. By default, the network of several protected areas across the country has provided protection to the majority of the widespread species (Burriel-Carranza et al. 2019; Cox et al. 2022), although habitat-specialists with limited ranges, often remain at risk and require protection within the areas they occupy.

Very few conservation efforts in the UAE have focused on reptiles. The first regional Red List for the reptiles of Arabia was completed in 2012, followed by the UAE National Red List in 2019, where conservation priorities were set to determine which species were at risk of extinction. The UAE endemic Emirati Leaf-toed Gecko, with its restricted distribution range along the East coast and severe degradation of its habitat due to development, was assessed both on a national and globally level as ‘Critically Endangered’ (Carranza et al. 2021). This species is still at the epicenter of several conservation efforts, which include establishing a Key Biodiversity Area and providing special protection to this unique vertebrate of the UAE.

The Wonder Gecko was assessed globally as ‘Least Concern’ (Els et al. 2019a, b), but due to its limited distribution range within Arabia which is threatened by development, the species was assessed regionally as ‘Endangered’ (Cox et al. 2012). The continued decline and fragmentation of populations alarmed conservationists, which resulted in the first reptile-specific Conservation Action Plan nationally (Soorae et al. 2018). Subsequently, the conservation status of the Wonder Gecko was nationally assessed in 2017 and 2019 as ‘Critically Endangered’ (Soorae et al. 2018; Els et al. 2019a, b). As part of several conservation efforts, which included studies on the genetic variability between fragmented populations, the Misnad Protected Area in the Emirates of Sharjah was established to protect this species within its natural habitat.

5 Conclusion

Among the resident terrestrial vertebrate fauna of the UAE, reptiles are the most species-rich group and can be found in all terrestrial habitat types, where they are essential components of the ecosystems and the food webs that they occupy. Through physiological and behavioral adaptations, reptiles were able to colonize much of the UAE despite the natural pressures imposed by the arid and thermally variable environment. Unfortunately, several reptile populations have declined recently due to urban development and related threats that have caused populations to become highly fragmented. Some species are habitat specialists, while others are generalists that have been able to colonize urban environments and live in close proximity to humans. Ongoing conservation efforts in various forms have ensured that reptiles are provided with protection, ensuring their survival for future generations.

6 Further Reading

For detailed accounts on the distribution of UAE reptiles see Burriel-Carranza et al. (2019). Information related to conservation of the two Critically Endangered reptile species see Tamar et al. (2021) and Carranza et al. (2016). See Šmíd et al. (2021a, b) for an overview of the regional distribution patterns of reptile species included in this chapter within Arabia. Species accounts related to amphibians see Burriel-Carranza et al. (2022), Gardner (2013) and Soorae et al. (2013).