54 research outputs found
Ecology of the lappet-faced vulture Torgos tracheliotus in Saudi Arabia
1- Food availability for the lappet-faced vultures was examined between 1993 and 1995. Several methods were used to estimate the number of ungulates in the area, such as aerial surveys, ground counts, questionnaires and the Ministry of Agriculture reports. The density of domestic livestock was estimated as 2.66 LSU's (LSU= Livestock Unit, one LSU equal one camel or ten sheep or ten goats). Based in studies in northern Saudi Arabia the expected carrying capacity of livestock in the study area is 0.3. This mean that the number of domestic livestock outside the reserve was nine times the predicted carrying capacity of the study area. A high mortality rate among the domestic herds provided a reliable food source for all the scavenging species in the study area. The wild ungulates were also examined, but their number was low, and their distribution was restricted to inside the reserve. There was no evidence of food shortage for the vulture population.
2- The pellets analysed from the lappet-faced vulture roost and nests sites at Mahazat as- Sayd reserve showed that they were heavily reliant on domestic ungulate carcasses. The birds might occasionally feed on live prey such as rodents and spiny-tailed lizards, but this was not a major source of food. However, there was no evidence of any seasonal variation in the type of carcasses used by the lappet-faced vultures.
3- The way in which different scavenging species located and exploited the carcasses was examined. Observations at carcasses placed in random sites showed that the brown-necked raven was the first species to arrive to the carcass. The lappet-faced vulture was the last species to find the carcass. They started foraging singly or in pairs and they moved in different directions, which would allow them to form a network in the sky and search effectively for food over a large areas. The number of vultures increased rapidly once the carcass had been discovered. The mammalian scavengers found few of the carcasses and were nocturnal.
4- The competition over the food supply was determined by measuring the amount of food removed by each of the scavenging species. Observations at the carcasses showed that the amount of food utilised by the avian scavengers was 30.4%, most of which was consumed by the lappet-faced vultures. The bill structures of the smaller scavenging birds are not adapted for tearing the skin of carcasses. However, different species of scavengers attended the carcasses at different times of the day. The small species fed in the early morning and late evening and the lappet-faced vulture concentrated on feeding in the midday. Therefore, there was no evidence that competition at the food sources had any effect on the lappet-faced vulture population.
5- The most important factor influencing the timing of breeding is probably the climate. Eggs are laid in winter to minimise the thermal stress on both the egg and the incubating adults. The number of active nests inside the reserve was far higher than outside the reserve, because the reserve provides an undisturbed area for breeding. Human disturbance is probably the main factor affecting the vulture population in the study area.
6- Observations at the nest suggested that the lappet-faced female may incubate the egg more than the male. The critical time in the lifetime of the lappet-faced vulture was probably the post-fledging dependence period, which could last up to 4-5 months. The majority of birds which died were found in this period.
7- During the first six months after fledging the distance covered by the fledging nestling increased significantly with age. There was a seasonal cycle of the lappet-faced vultures abundance at the reserve. The results from the movements of birds fitted with the satellite transmitters supported this cycle and suggested that some birds engage in short-distance migration within Saudi Arabia
Environmental proxies of antigen exposure explain variation in immune investment better than indices of pace of life.
Investment in immune defences is predicted to covary with a variety of ecologically and evolutionarily relevant axes, with pace of life and environmental antigen exposure being two examples. These axes may themselves covary directly or inversely, and such relationships can lead to conflicting predictions regarding immune investment. If pace of life shapes immune investment then, following life history theory, slow-living, arid zone and tropical species should invest more in immunity than fast-living temperate species. Alternatively, if antigen exposure drives immune investment, then species in antigen-rich tropical and temperate environments are predicted to exhibit higher immune indices than species from antigen-poor arid locations. To test these contrasting predictions we investigated how variation in pace of life and antigen exposure influence immune investment in related lark species (Alaudidae) with differing life histories and predicted risks of exposure to environmental microbes and parasites. We used clutch size and total number of eggs laid per year as indicators of pace of life, and aridity, and the climatic variables that influence aridity, as correlates of antigen abundance. We quantified immune investment by measuring four indices of innate immunity. Pace of life explained little of the variation in immune investment, and only one immune measure correlated significantly with pace of life, but not in the predicted direction. Conversely, aridity, our proxy for environmental antigen exposure, was predictive of immune investment, and larks in more mesic environments had higher immune indices than those living in arid, low-risk locations. Our study suggests that abiotic environmental variables with strong ties to environmental antigen exposure can be important correlates of immunological variation.Financial support came from the Schure-Beijerinck-Poppings Fonds (to NPCH and AH), BirdLife Netherlands (to BIT), NSF grant IBN 0212587 (to JBW), and VENI and VIDI grants from the Netherlands Organisation for Scientific Research (to KDM and BIT).This is the accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007%2Fs00442-014-3136-y
Two newly recognized species of Hemidactylus (Squamata, Gekkonidae) from the Arabian Peninsula and Sinai, Egypt
This is an open access article distributed under the terms of the Creative Commons Attribution License 3.0 (CC-BY),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.A recent molecular phylogeny of the Arid clade of the genus Hemidactylus revealed that the recently described H. saba and two unnamed Hemidactylus species from Sinai, Saudi Arabia and Yemen form a well-supported monophyletic group within the Arabian radiation of the genus. The name 'Hemidactylus saba species group' is suggested for this clade. According to the results of morphological comparisons and the molecular analyses using two mitochondrial (12S and cytb) and four nuclear (cmos, mc1r, rag1, rag2) genes, the name Hemidactylus granosus Heyden, 1827 is resurrected from the synonymy of H. turcicus for the Sinai and Saudi Arabian species. The third species of this group from Yemen is described formally as a new species H. ulii sp. n. The phylogenetic relationships of the members of 'Hemidactylus saba species group' are evaluated and the distribution and ecology of individual species are discussed. © Jiří Šmíd et al.The study was supported by the NAKI project of the Ministry of Culture of the Czech Republic (# DF12P01OVV021 MKČR to JŠ and JM), by grant CGL2012-36970 to SC from the Ministerio de Economía y Competitividad, Spain (co-funded by FEDER). We are thankful to the Deanship of academic research at Taif University for funding the sample collection in Saudi Arabia (Grant no. 1-433-2108) and to Omer Baeshen, Environment Protection Agency, Sana'a, Republic of Yemen for issuing the collecting permit (Ref 10/2007).Peer Reviewe
Are antimicrobial defences in bird eggs related to climatic conditions associated with risk of trans-shell microbial infection?
INTRODUCTION: All bird eggs are exposed to microbes in the environment, which if transmitted to the developing embryo, could cause hatching failure. However, the risk of trans-shell infection varies with environmental conditions and is higher for eggs laid in wetter environments. This might relate to generally higher microbial abundances and diversity in more humid environments, including on the surface of eggshells, as well as the need for moisture to facilitate microbial penetration of the eggshell. To protect against microbial infection, the albumen of avian eggs contains antimicrobial proteins, including lysozyme and ovotransferrin. We tested whether lysozyme and ovotransferrin activities varied in eggs of larks (Alaudidae) living along an arid-mesic gradient of environmental aridity, which we used as a proxy for risk of trans-shell infection. RESULTS: Contrary to expectations, lysozyme activity was highest in eggs from hotter, more arid locations, where we predicted the risk of trans-shell infection would be lower. Ovotransferrin concentrations did not vary with climatic factors. Temperature was a much better predictor of antimicrobial protein activity than precipitation, a result inconsistent with studies stressing the importance of moisture for trans-shell infection. CONCLUSIONS: Our study raises interesting questions about the links between temperature and lysozyme activity in eggs, but we find no support for the hypothesis that antimicrobial protein deposition is higher in eggs laid in wetter environments
Genomics reveals introgression and purging of deleterious mutations in the Arabian leopard (Panthera pardus nimr)
In endangered species, low-genetic variation and inbreeding result from recent population declines. Genetic screenings in endangered populations help to assess their vulnerability to extinction and to create informed management actions toward their conservation efforts. The leopard, Panthera pardus, is a highly generalist predator with currently eight different subspecies. Yet, genomic data are still lacking for the Critically Endangered Arabian leopard (P. p. nimr). Here, we sequenced the whole genome of two Arabian leopards and assembled the most complete genomic dataset for leopards to date. Our phylogenomic analyses show that leopards are divided into two deeply divergent clades: the African and the Asian. Conservation genomic analyses indicate a prolonged population decline, which has led to an increase in inbreeding and runs of homozygosity, with consequent purging of deleterious mutations in both Arabian individuals. Our study represents the first attempt to genetically inform captive breeding programmes for this Critically Endangered subspecies
Local Environment but Not Genetic Differentiation Influences Biparental Care in Ten Plover Populations
Peer reviewe
CHANGES IN THE NUMBER OF BREEDING PAIRS, NEST DISTRIBUTION AND NESTING TREES USED BY THE LAPPET-FACED VULTURE TORGOS TRACHELIOTUS IN THE MAHAZAT AS-SAYD PROTECTED AREA, SAUDI ARABIA
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Electrocution and collision of birds with power lines in Saudi Arabia
Abstract. A power line located 100 km south of Jeddah was monitored for four years (2008)(2009)(2010)(2011) and the results show that collision and electrocution of birds by power lines are of conservation concern in Saudi Arabia. The White Stork (Ciconia ciconia), Common Quail (Coturnix coturnix), Corncrake (Crex crex) and Willow Warbler (Phylloscopus trochilus) were the most affected species in the study area. However, the Common Quail seems to be more susceptible than other species and was found in high numbers. Although the number of species affected is probably low, the increases in energy demands and the introduction of new power lines will lead to an increase in bird deaths by electrocution and collision unless a conservation measure is applied to minimize the effect of power lines especially among the migratory species
Habitat selection by the Spiny-tailed lizard (Uromastyx aegyptia) : A view from spatial analysis
Many factors affect the habitat selection for animal species, which in turn may greatly affect their distribution in different ecosystems. Understanding the processes that affect habitat selection is also critical for guiding and managing conservation initiatives. Our study aimed to assess the habitat selection by free-ranging Spiny-tailed lizard (Uromastyx aegyptia) by analyzing a geospatial data connecting its burrow parameters to different habitat characteristics within selected sites in Hail region, Saudi Arabia. We examined evidence and patterns of significant spatial clustering for (366) active burrows by linking their parameters (burrow entrance size, burrow entrance width and burrow entrance height), their reference geographical locations and, two habitat characteristics defined by soil type and vegetation cover. The objective of the analysis was to increase the understanding on the burrows aggregation process in the space and, to describe its possible relation to other spatial habitat configurations. Analysis of distances based on the Nearest Neighbor Index (NNI) and hotspots detection in Nearest neighbor hierarchical clustering (Nnh) suggested twelve (12) spatial clusters located within the study area. In addition, a spatial ordinary least square (OLS) and Poisson regression models revealed significant effects of soil type and vegetation cover on burrow parameters (OLS, p < 0.05; Poisson, p < 0.001), which indicate a strong association between burrows parameters and habitats characteristics. Findings from the study also suggest that other factors such as elevations, highways, and human settlement concentration spots could possibly play a major role in defining burrow spatial aggregation and furthermore have a significant impact on habitat selection
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