An inventory of avian species in Aldesa Valley, Saudi Arabia

Conducting species inventories is important to provide baseline information essential for management and conservation. Aldesa Valley lies in the Tabuk Province of northwest Saudi Arabia and because of the presence of permanent water, is thought to contain high avian richness. We conducted an inventory of avian species in Aldesa Valley, using timed area-searches during May 10–August 10 in 2014 and 2015 to detect species occurrence. We detected 6860 birds belonging to 19 species. We also noted high human use of this area including agriculture and recreational activities. Maintaining species diversity is important in areas receiving anthropogenic pressures, and we encourage additional surveys to further identify species occurrence in Aldesa Valley.


Introduction
Global biodiversity is a consequence of evolutionary events that occur over time and space (Jetz et al. 2012). With current rates of biodiversity loss, understanding factors influencing species richness is critical , Pimm et al. 2014. Loss of biodiversity can directly and adversely alter ecosystem processes which in turn can affect the resilience of ecosystems to environmental changes . For instance, modifications in biodiversity may affect species traits and community composition, for example by the introduction of exotic species (Vitousek et al. 1997). Species composition and interactions between species, as well as abiotic factors, are the fundamental elements in any ecosystem (Groombridge and Jenkins 2002), with losses in biodiversity threatening ecosystems and the species communities living therein (Balvanera et al. 2006). Conservation of biodiversity is essential to ensure that ecosystems persist and function properly . Biodiversity losses can be irreversible; therefore, biodiversity should be monitored and protected , Brooks et al. 2006, and conducting species inventories are the most common approach to survey species richness (Hill et al. 2005).
Considerable variation in species richness exists, depending on ecological factors, with areas receiving higher rainfall having greater richness than dry areas, such as deserts (Gaston 2000). Deserts are defined as any ecosystem where limited water affects occurrence of species (Lawrence 2004), and desert ecosystems often contain the lowest species abundance and productivity (Waide et al. 1999). Hence, diversity and richness of terrestrial species in deserts are constrained by low rainfall, but high temperature also has a strong effect on species occurrence in deserts (Tiger andOsborne 1999, Gillman andWright 2014). Species richness is influenced by geographical composition (Brown et al. 2007), with valleys in deserts containing typically greater plant diversity, which in turn results in greater species richness of vertebrates (Qian 2007). Water may be more important to species where drought is continuous (AbuZinada et al. 2004). Access to water and related vegetation offered by desert valleys provide a higher quality habitat in terms of food and shelter for species (Slattery et al. 2003, Korine et al. 2015. Conservation programs often tend to emphasize regions with greater species richness, with most national and international conservation efforts occurring in these areas (Fa and Funk 2007). In contrast, comparatively few efforts are conducted in areas of low species richness, such as deserts. Though deserts do not typically support high species diversity (Walker 1992, Lawrence 2004, documenting and maintaining biodiversity in ecosystems with low diversity is important because it provides important information about species existence and richness which can be used to ensure the long-term persistence of species assemblages in these extreme conditions (AbuZinada et al. 2004 Annual rainfall is about 35 mm (Gosling et al. 2011).
Data collection. We conducted fieldwork from 10 May to 10 August in 2014 and 2015, having received permission from the Province of Tabuk and the University of Tabuk. We divided the valley, which is oriented east to west, into 40, 250 m long segments (Fig. 1). Each seg- ment was surveyed perpendicular to the valley (i.e. north to south), twice in 2014 and 3 times in 2015. We used timed area searches (timed counts) to quantify bird species occurrence, conducting searches from 06:30-10:00 h and arriving at the first segment 15 min before sunrise (Hill et al. 2005, Shirley et al. 2013. We conducted surveys when winds were < 12 km/hr and there was no rain (Ralph et al. 1995). We used a handheld anemometer (EA-3010U Handheld Travel Anemometer) to record wind speed and temperature during surveys. We searched segments for 0.5-2.0 h, with time spend depending on segment size and the complexity of vegetation, and using a predetermined schedule. We surveyed 4 or 5 segments each day. We used 2 field guides to aid in the identification of birds (Porter andAspinall 2010, Pope andZogaris 2012). For each observation, we recorded the time and the number of individuals by species. We made additional opportunistic observations outside of our timed searches. We used the IUCN Red List of Threatened Species (IUCN 2016) to determine the global conservation status for each species to provide an indication of the importance of the Aldesa Valley to vertebrate biodiversity within Saudi Arabia. We present the total number of times each species has been detected, as well as the number of segments in which each species was detected in each survey.

Results
We observed 2906 bird occurrences in 2014 and 3954 in 2015 belonging to 19 species, 15 families, and 5 orders ( Fig. 2  Material examined. Table 1; field observations and photographs.
Identification. This is a small common species ubiquitous to Aldesa Valley. The male has a gray crown, brown sides, a black bib, and white cheeks. The female is     Table 1; field observations and photographs.

Material examined.
Identification. The male has glossy, specular black plumage, and the female has a gray-brown sooty head. A conspicuous orange color on the wing can be seen during flight and when perched.    Material examined. Table 1; field observations and photographs.

Material examined.
Identification. Pycnonotus xanthopygos is easy to identify with distinctive yellow plumage on the under-part of the body. The belly and breast are dull gray with a sooty black head. It has a black bill and is dark gray-brown on upper parts.
Identification. The male of this species is very distinguishable and easy to identify. The body of the male is pink-rose in color with a sandy-brown tail. It has a conical-billed and the wings are pale-brown. The female is sandy-brown with sandy-pale buff underparts, faintly streaked on crown and mantle. Material examined. Table 1; field observations and photographs.
Identification. This species has a long curved bill. Male has glossy blue-plumage on breast and dark black plumage on the rest of the body. Female has pale-gray on under-parts and brown-gray on the upper-parts. The bill of females is slightly longer than in males.

Discussion
We detected 19 species of birds belonging to 15 families in the Aldesa Valley. Limited knowledge about species abundance and composition makes comparisons of species detected in Aldesa Valley difficult. Habitat heterogeneity typically provides diverse food resources; thus, higher species richness is expected in areas with such characteristics (Tews et al. 2004). The lower annual rainfall in deserts results in extreme drought most of the year and lower biodiversity (e.g. Arabian Peninsula; AbuZinada et al. 2004). Water, vegetation, and topography are key factors for species persistence in the extreme environmental conditions experienced in hot deserts (Tews et al. 2004, Korine et al. 2015. Perennial streams are rare in extreme desert environments, including Saudi Arabia (AbuZinada et al. 2004), which makes the Aldesa Valley unique. We suggest the habitat diversity in Aldesa Valley created by topography, vegetation, and especially permanent water is largely responsible for high avian species richness observed. Overall, there is a positive and fundamental relationship between habitat heterogeneity and species richness (Tews et al. 2004, Qian 2007.
We observed what we consider high avian species richness in Aldesa Valley, documenting 15 different families that accentuate the importance of this valley in the region. Such unique areas will likely benefit long term from increased official attention to help ensure species persistence and ecosystem function.
The Ministry of Tourism classified Aldesa Valley as a place for tourism in the Tabuk region (Saudi Commission for Tourism and Antiquities 2015). However, such a designation carries with it potential adverse consequences for the environment and biodiversity. Through this fieldwork and observations, we observed that tourism is causing negative effects on this ecosystem, as elsewhere in the world (Christ et al. 2003).
We observed numerous human activities in Aldesa valley that may adversely affect wildlife, including deposition of trash from tourists, occurrence of farms, and burning of trees. These human activities can influence ecological processes and landscape conditions which can adversely affect species richness and endemism (Vitousek et al. 1997, Hunter andGibbs 2007). There is potential for adversely affecting biodiversity if these disturbances continue.
Because of the uniqueness of the Aldesa Valley, we suggest that avian biodiversity conservation of this area should be a priority. We encourage authorities to consider monitoring human activities in this unique valley (Al-Moutirti 2004) to ensure long-term persistence of avian assemblages. We encourage additional inventories, including more detailed studies (e.g. night counts focusing on nocturnal species) on avian and other vertebrate groups, and ecological studies to further our understanding of the vertebrate community structure, dynamics, and species interactions in the Aldesa Valley.