A winter roost count of the Short-eared Owl Asio flammeus ( Aves : Strigiformes : Strigidae ) at Porbandar , Gujarat , India

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The Short-eared Owl has an extremely large range, and therefore it does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000km 2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation) as well as under the population trend criterion (>30% decline over 10 years or three generations) and population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in 10 years or three generations, or with a specified population structure) in IUCN conservation status evaluation.For these reasons the species is designated as Least Concern.
At present, due to their restricted nesting habits and nomadic nature, the species is vulnerable to habitat loss on their feeding and roosting grounds.Conversions of open habitats to agriculture, grazing, recreation, housing and tourism development are the current threats to the species in the wetland complex.
The Short-eared Owl is a common to uncommon winter visitor to Gujarat (Ganpule 2016).The species is usually present from September/October to March/ April in the Indian Subcontinent (Grimmett et al. 1998;Ali & Ripley 2001;Srinivasulu & Srinivasulu 2007).
The species usually nests and roosts on the ground and prefers grassland habitat.It is often seen flying low like harriers; its opportunistic diet consists mainly of small mammals and rarely small birds.It is an active hunter, flying low over the ground (less than 6 feet) in search of prey; usually hovers and drops vertically pouncing on prey.The species is considered to be a highly migratory in the northern limits of its global range.Banding data shows 1,000-mile movements in 50 days.These movements also vary and large movements are often related to juvenile dispersals.The longevity record for a Short-eared Owl in the wild is 13 years (Rumet 2012).

Material and Methods
Observations and counts were recorded in November 2016 for nine days in the Shiroda region, located between Odadar and Mokar villages of Porbandar District (Fig. 1).
It is located about a distance of 5km from Porbandar Somnath National Highway and connected by a tar road with Odadar and Mokar villages.The study area is Gosabara Mokarsagar Wetland Complex (here after Mokarsagar) which was declared an Important Bird and Biodiversity Area by the Bombay Natural History Society and Birdlife International in March 2017 (Rahmani et al. 2016).
Mokarsagar (21.565 0 N & 69.764 0 E) is the largest wetland of Porbandar District and spread across 106km 2 .The wetland complex supports more than 20,000 waterbirds annually and thus is shortlisted as a potential Ramsar site as well as Biodiversity Heritage Site.Recently, a public interest litigation has been also filed in Gujarat High Court to declare it as a wildlife sanctuary.
The wetland complex is drained by the Bhadar River, the longest river of the Saurashtra region along with River Billeshwari (Minsar).Before the 1970s, the region was an intertidal mudflat due to the ingress of sea water through the mouth close to Gosabara (21.535 0 N & 69.710 0 E) which mixed with fresh water during the monsoon season.The culvert was created near Gosa Village and resident fishermen used fixed oja nets for catching Prawns Penaeus penicillatus (Mansuri 1986).Gradually the tidal influx started impacting the soil and fresh water biota of the region.In order to prevent and control the impacting phenomenon Salinity Ingress Prevention Cell (SIPC), Gujarat, built structures across the creek such as tidal regulators (masonry wall) and bunds at different locations (Singh et al. 2014).These structures prevented the free flow of tidal ingress.As a result prawn fishing was stopped but the quality of agricultural soil improved.
In Mokarsagar, there are four elevated inland islands which usually do not get submerged during the peak monsoon (because the islands lie at about 4-6 m above sea level and the Mokarsagar is at sea level).Shiroda is one amongst these four islands mainly used by the Odadar villagers for grazing livestock.
The wetland complex has been monitored since 2012 for water as well as terrestrial bird count, the frequency is once every month of the year.On 9 November 2016, during the survey in Shiroda, one Short-eared Owl was observed and photographed in the bushes close to the road (Image 1).The bird was not disturbed and count and observation plan was structured to survey the region for the total wintering population of the species.
It was assumed that the Short-eared Owl will be present on all of the four islands of Mokarsagar.Starting from Shiroda, all islands were surveyed for presence of Short-eared Owls.The region was diligently surveyed on foot (after Fuller & Mosher 1987).Randomly, 500m long transect lines (total nine) were conducted in the study area.Walking the transects and counting of roosting birds on both sides and locations were geo-tagged with Garmin eTrex® 30x Handheld GPS device.Apart from Shiroda, the Short-eared Owl was not found on any of the other islands of Mokarsagar.Thus, the data presented is from Shiroda only.

Observation and Discussion
The species was found to roost in bushes of Prosopis juliflora on Shiroda island.Realizing the fact that the species was spotted for the first time, an effort for identifying communal roosts was undertaken by going on foot surveys.A total 20 individuals (Table 1) were observed to co-exist with grazing cattle in the grasslands spread over an area of 1km 2 between November 9-17, 2016 (Table 2; Fig. 2).The species prefers bushes to hide (Image 2) but, when unknowingly disturbed by cattle herders, it flies to refuge areas as shown in Fig. 1.The refuge area covers 0.14km 2 with dense vegetation of Proposis spp.along with grasses.
The species was observed to co-exist with mammals like Golden Jackal Canis aureus, Bengal Fox Vulpes bengalensis, Jungle Cat Felis chaus, Nilgai Boselaphus tragocamelus, Wild Boar Sus scrofa, and domestic cattle Bos domesticus.The species was also observed to co-exist with 48 bird species (Table 2).No attempts were made to study its interactions with other species.Generally, it remains silent during wintering stage thus no call was observed.
The current sighting of the Short-eared Owl in  Porbandar is the first published record for the district as it was not mentioned in previous checklists (Meena & Kumar 2014).Foot surveys were repeated for three days on the same transects and a maximum number of the owls were observed on the third day (i.e., 17 November 2016).Prey base and feeding ecology were not studied, however, we speculate that there is abundant prey at Shiroda Island & its adjacent farmlands, and the dense vegetation of Prosopis juliflora along with grass provide spaces roosting and sheltering.The present study is the first systematic attempt to count Short-eared Owls in Gujarat and reports the highest wintering roost congregation of the species.
Based on our limited study and data, we recommend that the management measures should maintain large contiguous tracts of wetland, and grassland habitat for the species and their prey.Controlled human disturbance and predation as well as possible, public education, and continued field research is required.

Figure 1 .
Figure 1.Study area (Shiroda island of Mokarsagar) of Short-eared Owl covering an area of 1km 2