Bird communities at an offshore island of Abu Dhabi, Sir Bani Yas, UAE

Bilal Kabeer, M.Phil.

Doctoral thesis

Abstract:

In hot arid ecosystems, birds are vulnerable due to changing, mostly warming, climate, reducing already scarce resources and impacting birds’ fitness. In deserts, human-made modification of habitats and intensive management represent potential mitigation measures to defeat these risks. Birds are recognized as important indicators of the state of the environment. Because they are sensitive to habitat change and they are easy to census, changes in bird populations are often the first indication of environmental problems. Sir Bani Yas is an important bird area and bird sanctuary as well as a wildlife reserve. The aim of the present dissertation thesis was to bring an insight into the bird communities at the Sir Bani Yas Island (SBYI), the largest off-shore island in the United Arabian Emirates in the Arabian Gulf. The investigation was focused on several parameters to characterise bird communities and their responses to the given environment. These parameters included; enlisting avian species, their feeding guilds, migratory and conservation status along with seasonal and inter-annual dynamics of the species richness, species diversity and equitability in bird communities in regard to habitats. Moreover, breeding performance of selected species, namely common kestrel (Falco tinnunculus), osprey (Pandion haliaetus), and Saunders’ tern (Sternula saundersi), with a focus on species abundance, nesting sites, clutch size, hatching success, and overall fledging success was studied. The island was categorized into four habitat types i.e. Forest, Coastal areas, Mountains and Pastures. Two transects of 800 × 100 meters were laid in each transect type. The data was collected from January 2014 until December 2018 through visual observations with the aid of binoculars and spotting scopes. Birds were identified through standard field guides. The observations on the breeding of osprey (Pandion haliaetus), common kestrel (Falco tinnunculus) and Saunder’s tern (Sternula saundersi) were recorded from January 2014 until May 2018. For this purpose, the nests were marked and were monitored until the chicks flew off the nest. We found the SBYI hosted a total of 164 bird species of all feeding guilds, Charadriiformes and Passeriformes being the most abundant, while there were 9 bird species before the SBYI was managed. The highest species richness and diversity was on irrigated pastures (mean 40.1 ± SE 1.4 species, mean Shannon-Wiener index H = 3.0 ± SE 0.03), followed by coastal area (mean 31.5 ± SE 0.7 species), forest (mean 22.0 ± SE 0.7 species), and rocky desert mountain (mean 21.3 ± SE 0.6 species). In all habitats, bird communities transformed following seasons, the species richness and diversity being highest in colder period while decreased during hottest months, the most on pastures and coast. Most species were migratory, suggesting the SBYI as a stepping stone supporting ecological connectivity in desert. Six nests of Saunders’s tern (12 nests total) were selected in each breeding season from April to June 2017 and 2018 (out of 9 and 8 nests, respectively). The mean clutch size during the two-year period was 1.50 ± 0.22 and 1.33 ± 0.21 (Mean ± SE) eggs per nest in 2017 and 2018, respectively. The mean incubation period was 18.97 ± 0.33 days. The mean hatching success was 62.5 % and 45 % in 2017 and 2018, respectively. Out of the 12 nests, three nests did not produce any fledglings, as one nest failed due to predation by feral cats and two due to anthropogenic factors. In common kestrel the courtship and nesting started during early April and the eggs were laid during late April. The average clutch size was 3.75 ± 0.31 eggs per clutch. The average incubation period was 29.13 ± 0.52 days resulting in average hatchlings of 3.50 ± 0.53 chicks. The eggs were incubated 74.02 ± 1.69 % and were unattended for 24.54 ± 1.64 % of the total incubation period. The provision of nesting platforms was successful in enhancing the repr

Abstract:

oduction rate of the Ospreys on the island. The nests on platforms were more successful in producing fledgelings compared to nests on natural substrates in disturbed habitats and with interspecies competition for nesting sites. The provision of platforms reduces competition for nesting sites and provides safety to adults and young. Our results indicate that ecological modifications on the SBYI coupled with protection of natural habitats provide a unique mosaic, which supports avian communities, and enhance ecosystem heterogeneity with the broader impact in the Arabian Gulf ecoregion. The finding of this study could be used as future reference to study the breeding success of the species and provide cues for further improvement of the ecosystem conditions by improving the habitat condition at the Island.

Keywords

community structure, species co-occurrence, extensive vegetation management, arid environment, artificial habitats

Language used: English

Date on which the thesis was submitted / produced: 4. 3. 2021

Thesis defence

• Supervisor: prof. RNDr. Pavla Hejcmanová, Ph.D.
• Reader: Miroslav Šálek, prof. Dr. Mgr., David Hořák, externi, Junid Nazeer Shah, externi

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Doctoral programme / field / specializace:
Agricultural Specialization / Tropical and Subtropical Agriculture / Živočišná výroba