http://docs.google.com/fileview?id=0B9H8J-6d_KrpMzdhMTlmNDgtNzJlNi00MjRjLTliMDktOGZhMjdmMjYxMjc4&hl=enEXECUTIVE SUMMARY
In an effort to better understand the seasonal movement of gharial in light of the unprecedented die-off in the National Chambal Sanctuary in the winter of 2008/08, a radio-telemetry research project was initiated in March 2009, continued from late June 2008. This MCBT/GCA project was based in Garhaita Village, Etawah District, UP, and conducted in collaboration with the Uttar Pradesh Forest Department and the Madhya Pradesh Forest Departments.
Ten gharial, 8 females and 2 males, ranging from 2.0 – 3.
3m (total length) were captured at two localities (Chilonga and Nakhnoli) on the Chambal river near Garhaita Village, NW of Udi. Individual gharial were outfitted with a distinctive radio transmitter and temperature data logger, tagged with a unique set of cattle tags, permanently marked (tail scute clipping) and released at the capture site (4 at Chilonga and 6 at Nakhnoli).
Capture/tagging was conducting by netting and tagged individuals were released the same day of the capture during the second and third weeks of March, 2009. The ten animals in the study group have been tracked for a total of 13 months through one summer season, one monsoon and one winter period.
Gharial under study showed well defined residence patterns, restricted to approximately 5km of river length, irrespective of season. During the monsoon months, the river length and area/extent of residences increased (by ~33-50%), but monsoon residencies remained well-defined and predictable.
The results of this study strongly suggest that the affected gharial in the current scenario were likely established residents in the immediate area with 5-20km upstream of the confluence. This may explain why the die-off was apparently greatest in the impact area vs. other area further upstream in the Chambal and/or downstream in the Yamuna.
Although environmental conditions during the summer season were ‘normal’, Etawah and surrounding districts experienced an unusually dry monsoon and very cold winter in 2009. Water levels in the Chambal river (by visual observation) are currently at an estimated 5-year low and the monsoon in 2009 was declared a failed monsoon by the IMD (Indian Meteorological Department). In light of this and other factors, it is proposed to continue the study for at least two more years, through 2011-2012, in order to examine animal movements during a ‘normal’ monsoon period and the subsequent dry season.
INTRODUCTION
1. Study Area
The National Chambal Sanctuary is a 428km stretch of the Chambal River, ending at the confluence of the Chambal and Yamuna Rivers at Pachnada and runs through the states of Rajasthan, Madhya Pradesh and Uttar Pradesh. The sanctuary area is located in a semi-arid zone in Northern India in the states of Rajasthan, Madhya Pradesh and Uttar Pradesh. Mean ambient temperatures range from 2-46 °C with a mean annual precipitation of 591.2mm, the bulk of which is received during the south-west monsoon months of May to August. The bulk of the sanctuary’s landscape is dominated by ravine thorn forest, and there is no evergreen riparian forest left – ground cover is generally sparse throughout. The Chambal river itself is a fast flowing river which originates in the Vindhya hill range of Central India, it flows north-east and eventually joins the Yamuna river at Pachnada, before eventually joining the Ganges River.
This research project was focused on a 115 km stretch of river from Pinahat (N26.864170° E78.363723°) to Sasoan Ghat (N26.543776° E79.088323°), which was the affected area of the die-off. This stretch of river, particularly the downstream reaches, was the epicentre (impact area) of the gharial die-off in the winter of 2007/2008. The telemetry study and the active tracking of animals have largely been confined to a study site comprising a 30km stretch of river, from Dinnpura (N26.779278° E78.725937°) to the Udi Bridge (N26.697508° E78.935026°).
2. Need for the study
As a direct result of a mass die-off of the critically endangered gharial in the National Chambal Sanctuary (NCS), there was an immediate need for an assessment of gharial health, population status, and the critical habitats necessary for the species' survival. In addition, this information is a prerequisite for any long-term comprehensive conservation plan. Current methodologies for obtaining these data consist primarily of information from rapid assessment surveys, and it was required to augment this data with detailed studies on gharial behavioural ecology and general biology, with a focus on home range as a tool to help assess the cause of the die-off.
With the assistance of the Forest Department we proposed to capture representative gharial in the impact and affected areas of NCS, mark individual animals with radio transmitters, and then monitor their movements and activities, as well as behaviors, throughout the seasonal cycles. In addition, this study would allow us to identify the critical habitats utilized by representative gharial in different seasons with special reference to their movements in the impact and affected areas of the recent gharial mass mortality.
We anticipated that the study results would yield new important information on gharials and their habitats. In particular, the expected outcomes were the following:
A) Assessment of health and status of gharial population in impact and affected areas,
B) Evaluation of hypotheses about causes/scenarios of recent mass mortality in NCS,
C) Determination of usefulness of telemetry for information necessary to mitigate crisis,
D) Procurement of essential data for a comprehensive species' conservation plan in NCS
The methodologies to be employed involved capture and handling by experienced personnel (MCBT capture team, Forest Department personnel and collaborators), marking and tagging with reliable radio transmitters (Dr. J.W. Lang,), and tracking and observations to be continuous throughout the annual cycle. Data collection and analyses with employ GPS-GIS location and mapping, GIS spatial analysis of gharial seasonal movements and critical habitats in the impacted and affected areas. The study was endorsed by the State Forest Departments of UP, MP, Rajasthan, the Ministry of Environment and Forests (MOEF) and WWF-India.
3. Rationale
In the light of the recent reversals, it is evident that there is urgent need for an immediate, as well as long-term assessment of gharial health, population status, and critical habitats necessary for the species' continued survival in the NCS. This requires in-depth knowledge about dispersal, movements and migration of the species which inhabits a linearly extensive habitat giving scope to long distance migration far beyond borders of protected areas in which they live. This has been sporadically documented, both directly and circumstantially.
There are limits to the current methodologies used for studying gharial, primarily rapid assessment surveys to answer specific questions regarding gharial seasonal movements and activities. In addition, it is important to determine the status of the gharial population (numbers, size/sex distributions, densities, etc.) and which particular habitats are required and/or critical to gharial populations.
Monitoring individual gharial is difficult without the use of radio telemetry, a tool widely used by conservation biologists to study a number of aspects of the ecology of many species. The recent mass die-off has shown that the conservation of gharial and effective management of similar situations like the one that arose, is not possible without knowledge of the spatial ecology of gharial.
4. Objectives of the study
1. To monitor seasonal movements and activities, including relevant behaviors, of gharial in affected size/sex classes throughout the annual cycle in the impact and affected areas, related to the recent mass mortality.
2. To identify critical habitats utilized by representative gharial in different seasons in the impact and affected areas.
PROPOSED METHODOLOGY
1. Capture
Gharial will be captured during daylight hours using primarily nylon multifilament set gill ‘Guchaila’ nets with continual surveillance of nets by experienced personnel under the supervision of experts and a veterinarian. Other, well tested, suitable crocodilian capture methods will be employed to supplement netting, as needed. Captures will be conducted main during the pre-monsoon period, but may be extended into the post monsoon period as well.
2. Restraint
Captured animals will be restrained by blind folding, taping jaws, binding of both limb pairs dorsally and finally securing by trained personnel. Animals will be measured and weighed then checked for external parasites and its over-all health status recorded by the veterinary doctor. Animals will be equipped with colored numbered plastic cattle tags to the single whorl tail scutes. Other veterinary samples will be collected where feasible.
3. Radio Attachment
Radio transmitters will be fixed to the caudal flanks on the double crest whorls near their junction with the single crest whorls. During the above operations, animals will be continually monitored and all required steps will be taken to prevent discomfort to the animals from overheating or desiccation. After compliance with the suggested protocol animals will be released at their point of capture.
4. Tracking
Receivers will be installed or deployed with multiple tracking personnel at an appropriate number of accessible tracking points on the river. Animals will be located by triangulation and/or direct observation. Animal locations based on tracking will be plotted on map sheets and environmental data and river flow conditions recorded. The Senior Scientific Advisor and project managers will make frequent visits to the different tracking personnel to monitor progress of the tracking and other studies.
5. Scope for additional studies
Clearly, there is an opportunity to obtain critical new information on the health status of the gharial living in the impact and affected areas during the capture and marking procedures planned for the proposed telemetry study. We have not addressed this aspect of additional veterinary studies in this report, but are mindful of this aspect, and will be willing to cooperate with the attending veterinarian to complete the collection protocols, where feasible, that may be deemed necessary.
RESULTS
1. Methodology and observations
A. Animal capture, restraint, and release
Gharial of the selected size class (2-4m total length) were very difficult to capture, particularly the larger size class (3.5-4m tl), and the present study is based solely on 2.7 - 3.3m adults and sub-adults. The successful capture strategy employed techniques developed by local fishermen, and entailed setting curtains of mesh netting at the deep water approaches to favored basking sites. Animals entangled in nets did not struggle, and consequently nets were checked frequently to avoid injury/drowning. Once secured with rope bindings on the limbs and snout, the captured gharial were remarkably sedate and docile, requiring a minimum of additional restraint, but protection from overheating by providing a large shade canopy and frequent wetting are essential while holding animals for tagging. On several occasions, it was necessary to retain animals for 8-10 hours prior to tagging, and under these conditions, the holding procedure that was used was well tolerated. Upon release, all tagged gharial reacted normally and typically showed defensive behaviors briefly and then bounded for the water and swam away quickly. A qualified veterinarian was on hand and assisted in all capture/tagging procedures.
B. Radio attachment
The rectangular, epoxy encased radio transmitters (60gm, 18x10x8cm) with trailing, flexible whip antenna (30cm) was attached to the base of tail just anterior to the junction of the single/double tail scutes. Stainless steel split rings (3, on bottom edge of each radio) were embedded in epoxy casing and were anchored with Kevlar fishing line that was inserted with the aid of a trochar style, large gauge needle as a guide, underneath the dorsal skin immediately below the bottom of the transmitter. Three strands of line were threaded through holes drilled at the base of the tail scutes on either side of the radio, and then tied to each of the three sets of rings. The knots were dabbed with 5 minute epoxy, and the knots further secured with metal swages, crimped on line ends. Local anaesthetic was available for use ad lib. Radio attachment was completed within 45-60 minutes, and well tolerated by all gharial so treated. In addition, a temperature data logger and visual cattle tags were used to provide individual identification, as well as permanent scute markings.
Figure 1: Picture taken in March, 2009 of the radio attached to animal number: 59, tagged in June, 2008 illustrating the robust nature of the radio attachment procedure followed.
Figure 2: Tail section of Animal Number 57, after attachment of the radio, data logger, and uniquely coded cattle tags. This animal is ready for release.
C. Transmitter function
The transmitters (151 MHz; Advanced Telemetry Systems, USA) were designed to be functional for 2.5-3 years, and under Chambal conditions, have an effective signal range of 0.5-3 km, dependent on local terrain and prevailing weather conditions. Listening posts, on high ground (locally known as a tapu) were established about every 2-3 km along the riverside. Limited vegetation in the river valley and high vantage points facilitated signal reception; maximum reception was >5 km under ideal conditions. Daily observations indicate that specific behaviors and activities of an animal correlated closely with signal strength and signal variation. For example, a gharial swimming can be distinguished from one sitting stationary on land, e.g., basking. Submergence under water results in signal loss at 2-3 m, and continual visual observations while monitoring signal strength confirmed that submerged animals were detectable even when the gharial surfaced for brief periods, e.g., 1-3 minutes. In the dry season when gharial spend hours submerged, monitoring was extended for .5-2.0 hours at listening posts in order to adequately track resident gharial when they surfaced periodically while remaining underwater during midday.
By carefully noting signal variations, a variety of animal activities/behaviors can be detected from signal variation alone, and subsequently confirmed by repeated visual sightings. All of the above protocols have been incorporated into the routine data recorded at each tracking site. The absence of a signal for a 1-3 day period indicated that an animal was likely no longer present in the area. At all listening posts, the trackers scanned all ten frequencies for signals, to prevent bias in anticipating an animal’s whereabouts by selectively tracking only known local residents.
D. Disturbances associated with capture/tagging
Capture/tagging activities in mid March ’09 extended over two weeks and resulted in disturbance at the two capture sites for the following 4-6 weeks and typical/normal behaviours, primarily basking, by gharial at these sites were only resumed by tagged as well as untagged individuals in late April/early May. Following this interruption, tagged gharial resumed association with untagged individuals and regular patterns of activity were exhibited by all resident gharial.
Tracking from listening posts on riverside high ground resulted in minimal/negligible animal disturbance, whereas tracking by boat (technique used initially) was much less productive and appeared to create a much greater disturbance which interfered with radio-location, e.g., gharial submerged on approach, and signal detection was not possible, nor were any visual sightings.
The Chambal gharial populations resident at specific localities appear to be habituated to normal riverside activities, and display finely tuned discrimination abilities when reacting to human activities close to basking and/or nesting sites particularly. Gharial are alert to calls/signals of other sentinel riverbank inhabitants such as shorebirds and wading birds, and typically react to their alarm calls signifying unusual, atypical, often threatening activities. Gharial rapidly head for water if basking, or submerge if in the water until the potential threat wanes or disappears. Habituation to villagers using footpaths, walking with livestock, moving with camels, even crossing shallow stretches of river on foot/camel is evident, and these activities are ignored and not responded to with escape behaviors.
In contrast, the capture-tagging forays to affix radios continued for days, and even residual human activities loosely associated with capture, such as tracking/observing, resulted in daily disturbances to normal patterns of basking and submergence by resident gharial. Frequent major disturbances at some localities appeared to result in resident gharial shifting their “normal” daily locations to nearby, undisturbed areas.
Based on repeated observations reinforcing the summary of disturbance factors (above), the optimum time for capture/tagging would appear to be in the immediate post-monsoon months (Oct-Dec) to avoid interference with important social/reproductive behaviors known to occur from mid January through the pre-monsoon months (May, June, early July) when nesting, hatching, and parental care of young has been observed in Chambal localities.
E. Tracking Methodology
The tracking team, based at Garhaita Village, consisted of 2 experienced local trackers who also operated an inflatable boat with a 25hp OBM, and 2 researchers who worked with the trackers to locate telemetered gharial along a 30km stretch of river which was monitored 3-5 days a week. Local transport was primarily river transects on foot and/or by motorbike. High ground overlooks were located at strategic sites which provided upstream and downstream coverage by utilizing 4 element Yagi antennas as well as 3-element handheld units with portable field receivers (ATS Fieldmaster 100) that provided optimal tracking ranges of 0.5 -3.0km, dependant on local terrain and weather conditions. The tracking field team, consisting of 3 trackers, logged a total of 241 days of the 412 day tracking period. A summary of the tracking effort is presented in Table 1.
GPS readings (Garmin Vista HCX) were taken for animal locations by triangulation on constant signals, and when feasible (ie. when tagged animals were visible), this data was collected by waypoint projections using a compass bearing along with a laser range-finder (Bushnell Sport 450).
F. Tracking effort
One radio-tagged gharial (59) has been monitored for 9 months (June ’08 – Feb ’09 intermittently; followed by 13 months regularly). The ten gharial outfitted with radio transmitters (151 MhZ; individual frequencies) have been tracked for approximately 50% of the total days (2432 of the total gharial days tagged, which were 4120) between release in mid-March and 30th April, 2010. For the ten gharial monitored for 13 months, locations for 1795 daily monitoring gharial days were recorded, for an average of 180 tracking days during the mean 412 days tagged, or approximately 44% of the days monitored. A total of 1812 daily locations were recorded for the ten monitored gharial during the 13-22 months of the study. In addition to daily tracking locations, detailed observations were recorded of environmental parameters, water levels (river) and gharial activity and behaviour, throughout the daylight hours, including morning and afternoon observations. Photos of gharial groupings, including those which included tagged gharial were taken frequently, daily to weekly, to further document gharial locations and habitat usage.
Figure 3: A view of one of the main basking sites, Chilonga, with the tracking team in the foreground. Trackers work alone or in pairs decided by a work plan formulated the night before.
In addition, hand drawn sketches and marked printouts of satellite maps were maintained for the most important basking sandbanks. Observations/tracking effort, consisting of daily forays of 6-10 hours, were seasonally adjusted to accommodate local weather conditions and, importantly, to the seasonal changes in gharial activities – early morning and later afternoon observations during periods characterized by the warmer, dry months (March –July; Sept-Nov) and midday observations during the wet period (July-Sept) and also for the winter months (Nov-Feb).
2. Movement Patterns and Spatial Ecology of Chambal River Gharial
During the dry season/low water conditions, normal activities consisted of loose aggregations of gharial of all sizes at particular deep water areas, pools with riverside sand banks, sand bars and exposed mid-river sand islands. This “clumped” distribution of gharial is characteristic of all months of observation, except the high water/monsoon months of July, August, September and October.
A. Synopsis
The radio-tagged gharial monitored for 13 months (Mar ’09 – Jan ’10) exhibited individually distinct patterns ranged from residency at a single location (61 at Chilonga) to wide-ranging movements upstream as well as downstream, by a gharial (59 at Nakhnoli) whose residency was loosely centred at a mid point 6km below the furthest upstream location, and 10km above the furthest downstream location. The home range of the radio-tagged animals has, for the most part, been within the 30km stretch which was the main study site, although some animals (63 and 49) have been found outside this range. The 3.3m female, 63, has been recorded 22km upstream of Dinnpura and another female, 49, has been recorded about 5km downstream of the Udi bridge.
Summaries of the residency patterns are presented in Table 2, and further details of individual patterns, as well as size estimators during the dry season vs. monsoon months are shown in Table 3.
B. Seasonal trends
Most tagged gharial showed well-defined seasonal patterns of residency, with upstream primary (low water/dry season) location(s) and downstream secondary (high water/monsoon months) residences to which each moved during August-October, and then each returned to its primary residence upstream in subsequent months. Two tagged gharial (49 and 57) varied this seasonal pattern by remaining at downstream locations and/or visiting these during the post-monsoon, dry season as well. Two other gharial (75 and 69) with upstream residencies shifted frequently between their primary residencies and nearby localities, presumably in response to high water fluctuations that inundated mid-river islands at Dinnpura.
Seasonal shifts to monsoon residencies during the high water months of August-Sept-Oct involved shorter distances (4-7km) or longer distances (14-16km), by gharial from dry season primary residencies at Dinnpura as well as those residing at Chilonga.
C. Distance trends
Three gharial tagged at Chilonga had their primary residency at Chilonga, and either didn’t move downstream (61) or made shorter movements to secondary residencies downstream (55 and 63). Three Dinnpura residents (53, 69 and 75) moved shorter distances (7km) to secondary residences while another Dinnpura resident, 51, shifted a longer distance (16km) to its secondary downstream residence.
Two other Chilonga residents (49 and 57) moved downstream and back upstream with less obvious seasonality, involving longer downstream shifts in residency. These gharial appeared to have shifted their dry season residencies in 2009 to locations downstream in 2010, and resided at or nearby their secondary residencies downstream that were occupied during the 2009 monsoon.
The mean for the ten monitored gharial was 10.2 km, but varied from <> 10km. The typical transit patterns are illustrated by the travel narratives of three gharial (51, 57 and 63) which are presented in detail in the sections below.
E. Movement summaries for three selected individuals
To illustrate movement patterns of these three animals, residency and movements patterns have been superimposed on satellite imagery and the resulting outputs have been shown for these three animals (51, 57 and 63). Downstream routes are denoted as yellow lines with downstream stops marked as yellow balloons; upstream routes are denoted as red lines with upstream stops marked as red balloons.
Figure 4: Movement map for Animal Number 51 showing a summary of major movements made from March 2009 to April 2010
i. Movement Summary (2009 - 2010) – ID: 51 (2. 8m Female, captured at Nakhnoli)
This individual (51), a resident of Dinnpura and Akon Ki Mauriyan during the months of May-July, has been tracked for a total of 255 days till date (30/04/10). During the tracked days, it was found on 197 days (or 77% of the time). The total number of days this animal has been tagged is 410 and it has been tracked for 48% of the total number of tagged days.
During the months of May-July, 51 moved from Dinnpura to Akon, a distance of 2.4 km, several times but remained resident in this general area. In early August, 51 made a downstream transit, first to Nakhnoli (6.9 km) and then to Chilonga (5.3 km from Nakhnoli) – a total distance of 12.2 km. Transit time from Nakhnoli to Chilonga was 1 day, and Chilonga was used as a temporary residence for 15 days.
September saw another downstream movement by 51, from Chilonga to Pachai Gaon, a distance of 4.2 km which was covered in a single day. Pachai Gaon was used as a temporary residence for about 4 days. Following the residence at Pachai Gaon, 51 moved back upstream to Chilonga in October, again covering a distance of 4. 2 km. Chilonga was again used as a temporary residence for a further period of 15 days. 51 then moved upstream to Murong and spent 2-3 days resident at this site.
In early November, 51 moved upstream from Murong to Nakhnoli covering a distance of 3.4 km with a transit time of 2-3 days. In mid-late November, 51 again moved upstream, back to its May-July residence just below Dinnpura at Akon and Karot 4.5 km upstream of Nakhnoli.
In late December, 51 moved upstream 2.4 km to Dinnpura and was resident in Dinnpura for 2 days following which there was a 6.9 km transit downstream to Nakhnoli. The downstream movement to Nakhnoli coincided with a rise in water levels and submergence of some basking sites at Dinnpura. 51 has been resident at Nakhnoli and nearby sites just upstream during late January and early February, and then returned to Dinnpura briefly for 3 days before shifting 5 km downstream to Karot where it resided thru all of April. The total distance traveled by 51 over this 13 month period was 54.5 km, the sum of all its recorded transits. It made a minimum of 15 trips, 8 up and 7 downstream (Table 2).
Figure 5: Movement map for Animal Number 57 showing a summary of major movements made from March 2009 to April 2010
ii. Movement Summary (2009 - 2010) – ID: 57 (2.9m Female, captured at Chilonga)
This individual was observed to use the Chilonga basking site fairly exclusively during the months of May, June and July. During this period, the animal was tracked for a total of 57 days and was recorded exclusively at Chilonga (it was not recorded for 12 of the 57 tracking days – it was not found for 21% of the tracking days).
In early August, the animal left Chilonga and moved downstream to another well used basking site at Badpura. The transit time for this move was 5-6 days, and the distance covered was 14.3km. 57 used Badpura as its primary residence for a period of 15-20 days.
In mid-September, 57 moved upstream to a site near the village of Baswara, where it was resident for a period of 10-15 days. This distance travelled over this transit was 6.7 km. In early October, levels of disturbance were observed to increase at the Baswara site, and 57 left Baswara and made another upstream transit to Pachai Gaon, a distance of 3.4 km. The Pachai Gaon site was used as another temporary residence and the animal spent ~15 days at this site.
Late October to early November saw 57 making another downstream transit from Pachai Gaon to Baroli, a distance of 6.9 km with a transit time of about 5 days. Baroli was used as another significant temporary residence site and 57 spent the months of November, December and most of January there.
In late January, 57 left Baroli and moved upstream to Chilonga, with no recorded stops along the route, and over a transit time of 1-2 days. This distance travelled was 11.1 km, and the animal has remained at Chilonga for 3 days, before returning to Baroli to the same locality it had occupied previously. It remained there til mid March, when it shifted downstream 3.2 km to Badpura, stayed there one day, and then returned to Baroli through the rest of March and all of April.
The total distance recorded travelled by 57 over this 13 month period was 66.2 km, the sum of all major transits it made during this time. It made a minimum of 11 trips, 5 upstream and 6 downstream (Table 2).
Figure 6: Movement map for Animal Number 63 showing a summary of major movements made from March 2009 to April 2010
iii. Movement Summary (2009 - 2010) – ID: 63 (3.3m Female, captured at Chilonga)
A female (63), the largest gharial radio-tagged, remained near the capture site (Chilonga) only a few days after release in mid March, and was not located again for 121 days. Then she reappeared at Murong, 1.8km upstream from Chilonga in mid July 2009, after an absence of 4 months.
In 2009, her 121 day absence from mid-March to July corresponded to the period of nesting, incubation and hatching, and may represent a shift to nest elsewhere. However, frequent monitoring attempts to locate her within the 30km river section from Udi Bridge to Dinnpura failed to locate 63 during this period, monitoring of known nesting sites, upstream for 20km and downstream for 16km also failed to detect her on numerous occasions.
Subsequently, she remained at Chilonga continuously, with a high water shift downstream of only 4.2km to Pachi Gaon for 3 weeks, then returned to Chilonga where she has resided with frequent track locations all from Chilonga.
In late February of 2010, she again “disappeared” from Chilonga, her place of residence since mid July 2009 (with limited downstream movement during the monsoon). A concerted effort to locate her near known nesting areas, primarily upstream, did result in definite track locations at Gohera, above Naandagoan, a river distance of 34 km upstream in early March, but she has not been relocated subsequently during the remainder of March and April.
F. Summary of movement patterns observed
The details of individual gharial’s seasonal patterns of residency (dry season vs. monsoon) with respect to the main center of activity, home range size and area estimates, and movement direction and summed movement totals are presented for the ten telemetered gharial in Table 3. Each gharial had a well defined activity center from which it made excursions, typically return trips, periodically. Home ranges consisted of all tracked locations, and were larger during the monsoon months. River lengths (between most distant points of home range) averaged 4.0 km (range 1.3 to 7.3 km) in the dry season vs. 6.5 km (range 3.2 to 10.1 km) during the monsoon. Home range area (river length x river width seasonally) averaged 92 ha (range 38-208) in the dry season vs. 322 ha (range 159-503) during the monsoon. The predominant movement direction was downstream during both seasons. Trip frequency, reflected in summed movements, was not obviously related to either size or extent of home range estimates. Tracker observations strongly suggest that many short trips were directly in response to water level changes (e.g., dam releases innundating basking sites, and/or specific human activities close by basking areas that directly interfered with the daily basking routine).
Although the seasonal patterns of residency summarized here were notably consistent fo all of those gharial monitored, four individuals (59, 57, 49, and 63) showed departures from the general pattern. Two (57 and 49) shifted their dry season residences downstream during 2010, close to where they initially shifted during the monsoon from previously occupied upstream residences. Another (59) had an activity center that didn’t shift seasonally, but tended to move upstream during the dry and downstream during the monsoon. Finally, the largest female (63) disappeared coincident with the nesting/hatching periods in 2009, and again in 2010.
3. Synopsis of daily activities, behaviors, and social/reproductive behaviours
A. Basking
As noted earlier, the daily activities/behaviors of all the gharial observed on this stretch of river are well established and predictable, but vary in major aspects with respect to season. Basking, with an obvious thermoregulatory function, occupies most of the daylight hours during the cooler, winter months (Nov-Mar) and wanes as ambient temperatures (water and air) increase during the warmer, summer months (Apr-Oct). Despite hundreds of hours of observation at major basking sites frequented by gharial of all size/age classes, feeding behavior was rarely observed. Nightime observations were not possible, but limited feeding may occur then. In contrast, feeding was often observed during the monsoon months when gharial are less aggregated and dispersed along shorelines and adjacent flooded channels and backwaters.
B. Social interaction
Social interactions at basking sites were also rarely observed, but likely involve subtle and complex responses to well established social hierarchies. In particular, large juveniles and small subadults (1.5 - 2.5m total length) tend to associate with each other, and have been observed to be approached and chased away from basking groups by larger gharial. But overall, there is little defined separation of habitat usage among all size/age classes.
C. Nesting
Nesting at selected, traditional sites occurs in late March and early April at this locality and is preceded by social groupings during late Jan-early Mar which appear to include one or more ghara-bearing males, and an assemblage of potential nesting females at these sites. Young from the previous year associate closely with each other and have been observed to be attended, even at 9 months of age, by large adults, especially the dominant resident male at Chilonga in Feb-Mar 2010.
Nesing females and/or dominant males at these sites remain close to nests, once these contain eggs, and closely approach intruders and/or potential predators of eggs/hatchlings. Once nests hatch, at sites containing multiple hatchling groups, hatchlings have been observed to form exceptionally large groups, >120 individuals, closely attended by one or more adults (female and/or male), presumed to be parents. In contrast to all other settings, adults tend to remain vigilant and decidedly more visible when attending hatchling groups, and tolerate close approach and may even exhibit defensive, aggressive behaviors toward intruders in response.
4. Nests monitored and reproductive success
In an effort to further evaluate the health of the Chambal River gharial population under study, e.g. its reproductive success, nest monitoring was done whenever possible during 2009, and systematically during the 2010 season to date. These observations include river stretches from Pinahat to Sashon Ghat, and encompassed 3 survey segments (~100 km river distance). In 2009, at least 20 trial nests were observed, and successful hatching was recorded for at least 10 nests located at 5 localities. No obvious abnormalities and/or nest failures were noted at any of these sites.
In 2010, nesting effort was monitored on the same stretches of river. As of end of April, a total of 14 nests were recorded, of which 2 were predated. Nest surveys will be continued as long as possible pre-monsoon to provide additional data on nesting effort and nest success.
5. Population counts and composition in the study area
A. Trends
Total population estimates in the study area at six localities frequented by resident radio-tagged gharial are presented in Table 4. The maximum number of gharial in various size/age/sex categories at each site in 2009 and in 2010 is based daily counts on > 20 days taken at peak basking time under favorable weather conditions. Sizes were estimated based on markers on basking beaches and further refined by calibrating size estimates using telemetered gharial (of known size) in basking groups. Only data from undisturbed groups were included in tally, and single animals/isolated small groups were not included in these counts. Consequently, these counts may not be directly compared with boat/bankside surveys which tally total counts for specific river stretches.
B. Encountering of Telemetred individuals
Telemetered gharial monitored during this study were evident in most counts at all localities, dependent on an individual’s residence patterns and associated movements. It is important to note here that detailed daily observations of the ten radio-equipped gharials indicate that not every gharial “basks” or moves onto land on every single day, and often telemetered gharial were detected by signal strength to be located nearby basking groups, but simply were not on land and not visible to be included in these daily counts. As many as three radioed gharial (at Dinnpura, and at Chilonga) were known to be present based on signal strength and position, but not visible, accounting for 30-50% of the total population observed to be on land and included in daily counts.
C. Overview
The number and age/size composition of gharial residing at each basking locality, based on these popultion counts, indicate: 1) stable numbers of gharial are found aat specific localities within a seasonal period, and also from year to year, 2) the distribution of size/age classes strongly suggest that reproduction and annual recruitment of appropriate age/sze classes is occurring, and 3) if telemetered gharial are representative with respect to their residency/movements, then most gharial observed at a given locality are seasonal residents as well, with well-defined seasonal patterns of movement.
DISCUSSION
1. Assessment of health and status of gharial in impact and affected areas
The Focus of this study has been on gharial populations in a 30km stretch of the affected area, utilizing ten telemetred residents gharial in conjunction with total population counts, augmented with nesting observations in the impact/affected areas.
The results presented in this report indicate:
i. Population composition (size/age class distributions at selected basking sites) is normal in comparison with previous annual boat surveys conducted prior to the die-off
ii. Likewise, nesting and hatching observations in 2009-1010 indicate that reproduction in these populations is normal. There is no evidence from our study of any abnormalities and/or nest failure in 2009-2010 to date
iii. There is no evidence of any sick/dying gharial during this study, and no “abnormal” behaviour and/or activities were exhibited by any gharial in this study
iv. No additional veterinary assessments of gharial health were conducted in conjunction with this study, due to funding and logistical constraints
2. Evaluation of hypotheses about causes/scenarios explain mass-mortality of gharial in the NCS
i. Gharial under study showed well defined residence patterns, restricted to approximately 5km of river length, irrespective of season. During the monsoon months, the river length and area/extent of residences increased (by ~33-50%), but monsoon residencies remained well-defined and predictable.
ii. Residency shifted 5-20km downstream for radioed gharial, during the highwater period, “failed” monsoon of 2009, with a single exceptional animal that moved upstream as well as downstream.
iii. Current scenarios explaining the die-off suggest that gharial residing in the Chambal moved downstream to the Chamba-Yamuna confluence and resided there during the 2007 monsoon. Some of these individuals may have moved upstream some distance into the Yamuna river, as was observed post-dieoff in the 2008 monsoon.
iv. The results of this study strongly suggest that the affected gharial in the current scenario were likely established residents in the immediate area with 5-20km upstream of the confluence. This may explain why the die-off was apparently greatest in the impact area vs. other area further upstream in the Chambal and/or downstream in the Yamuna.
v. Feeding on a regular basis by gharial appears to be restricted primarily to the monsoon months of high water. The occurrence of the die-off in winter months of Dec – Mar (2007-2008) suggests that the consequence of exposure to presumed toxins in the Yamuna was delayed for months and/or accelerated by low winter temperatures. At present, a definitive cause for the 2007-2008 mass mortality even has not been established.
vi. The 2009 monsoon was not “normal” but occurred late with minimal rainfall and consequent high water, so the wet season responses of gharial, particularly monsoon movements and season shifts in residence patterns, remain poorly documented. Consequently, the results of this study to date have limited relevance to current scenarios to explain the die-off.
3. Determining the value of telemetry for ecological information relevant to long-term gharial
conservation
i. Identify critical habitats used by individual gharial throughout the year, both dry season and monsoon. In the present study, river stretches of 5-20km are utilized by gharial observed at a specific locality.
ii. Delineate existing gharial populations in relation to the critical habitats they require, and characterize these with respect to age/size/sex grouping, including social determinants of gharial spatial ecology
iii. Design rigorous survey methodologies to accurately census known, established gharial populations, as well as develop reliable rapid assessment techniques.
iv. Document how existing gharial populations respond to natural environmental changes, and, in particular, react to potential man-made disturbances.
v. Study important behaviours, such as prolonged parental care of young, which should provide useful guidelines for release/reintroduction schemes
vi. Evaluate the success, cost-effectiveness and appropriate time of year for release/reintroduction schemes that involve various ongoing activities such as egg collection, hatchling rearing, head-starting, and juvenile release.
vii. Using “adaptive management”, develop appropriate and effective in-situ management strategies, such as nest protection, targeted habitat protection/restoration, mitigation of man-made disturbances, and other strategies that aim to augment existing gharial populations and their critical habitat.
4. Procurement of essential data for a comprehensive species recovery plan in NCS
Gharial respond to changes in the local environment by shifting residence on a seasonal basis (dry season vs. monsoon) and/or in response to specific events, eg. Direct human disturbances, water level alterations, etc. In this regard, the integrity and continuity of the river channel or an all essential movement “corridor”, unimpeded and unrestricted, is critical to the continued health, well-being, and survival of Chambal river populations of gharial. The present study indicates that adequate water flow is necessary for maintenance of deep water pools and movements between pools via sufficient shallow water channels between pools.
Access to river flow data would be of extreme value to the meaningful analysis of home range data and general ecological data, and would be key to the formulation of any new gharial management plan for the NCS.
Telemetry studies of gharial spatial ecology will also be a necessary component in studies to:
i. Quantify river features which are vital and critical to the gharial’s continued survival in NCS, in particular water quality and water flow regimes integral to river ecology.
ii. Quantify seasonal features of river ecology, such as access to shallow water and the continued presence of healthy aquatic prey, particularly native fish species.
iii. Identify man-made disturbances, asses their impacts/threats, and quantify levels of disturbance which are tolerated as well as those which are not.
RECOMMENDATIONS
On the basis of the results of this study, the following recommendations are made:
i. Continue studies now underway for at least two additional years, 2011 and 2012 so that gharial ecology, especially movements and residency patterns can be further documented through a “normal” monsoon wet season and following dry season. In addition, larger size classes, 3 - 5m adults, should also be radio-tagged and monitored as well. Gharial now tagged should be refitted with radios for telemetric studies through 2010.
ii. Current efforts should be augmented and strengthened with additional staffing and logistics. Behavioural/observational studies should be increased and expanded, and night observations permitted wherever and whenever feasible.
iii. Similar studies utilizing radio-telemetry should be initiated in representative gharial populations in one or more other river segments of NCS in order to establish a broad database for a comprehensive species recovery plan and consequent effective management of gharial in the NCS.
ACKNOWLEDGEMENTS
We would like to thank everyone who has helped make this study a continuing success, and would like to particularly thank the following individuals and organizations for their contributions:
Dr. Anmol Kumar, MOEF
Mr. B.K.Patnaik, UPFD
Dr. H.S. Pabla, MPFD
Staff of the Uttar Pradesh Forest Department
Staff of the Madhya Pradesh Forest Department
Mr. Neeraj Kumar, UPFD
Mr. Pankaj Kumar
Mr. Anand Kumar
Dr. Gowri Mallapur
Rogier Van Rossem
Mr. Shailendra Singh
Mr. Ravi Singh, WWF-India
Dr. Parikshit Gautham, WWF-India
Mr. Romulus Whitaker
Ms. Janaki Lenin
THIS PROJECT WOULD NOT HAVE BEEN POSSIBLE BUT FOR THE VERY GENEROUS GRANTS FROM THE FOLLOWING ORGANIZATIONS:
SAN DIEGO ZOOLOGICAL PARK
ZOO PRAHA
OCEAN PARKS CONSERVATION FOUNDATION
THE RUFFORD MAURICE LIANG FOUNDATION
CLEVELAND METROPARKS ZOO
