GHARIAL: MAIDEN CLUTCH AND NEST SITE STRATEGY

Background to this blog. On May 19, 2021 28 gharial hatchlings were observed with a female in Satkoshia Gorge of river Mahanadi, Odisha state. The river stretch is in Satkoshia Gorge Sanctuary (1976) that was constituted under and a part of the national crocodile conservation project of Government of India launched with support from UNDP/FAO. 

While I congratulated the officers who have ensured to regulate habitat disturbances by people, I also mentioned that 28 hatchlings mean it is not the maiden clutch, and that the reproductive effort of the female in previous year(s) had remained unnoticed. 

This prompted me to look back on my data and interpretations on two subjects: 

(A) What is the minimum clutch size?  (1.) In my PhD dissertation (Singh 1978, Table-11) I provided data on 27 nests from rivers Narayani and Kali, Nepal relating to the years 1976 and 1977. Out of these, six nests had less than twenty-five eggs. As a practice in hatchery incubation, nest-wise we examine all unhatched eggs. There were three completely infertile nests with 10, 16 and 24 eggs. Out of the remaining three nests with 12, 18 and 16 eggs, the hatching success were 75, 16.7 and 50%.

(2.) Sunil L. Rajbhandari and Paras M. Acharya (2015, Report to Rufford) have reported the smallest clutch with just 6 eggs in 2014 and 18 in 2013, both at different places in Narayani river.

(3.) Tirrtha M. Maskey (PhD thesis, 1989), studying in Nepal, reported the smallest egg clutch of 16 in 1977, 18 in 1978, 14 in 1979, 14 in 1980, 30 in 1981, 31 in 1987. So, some movement or pushing out of the main congregation may be occurring to reduce competition in resource partitioning.

(4.) Khadka et al (2020, Herpetologica) have provide data on 151 Gharial nests over 17 years in sand banks along the Narayani (n = 94 nests) and Rapti (n = 57 nests) Rivers in Chitwan. Based on the range of clutch size given, the year-wise smallest clutch was with 21 eggs (2003), 11 eggs (2004), 23 (2006), 19 eggs (2010), 23 (2011), 7 (2012), 23 (2013), 6 (2014), 12 (2015), 16 (2016), 19 (2017),

(5.) Our team in Chambal observed 17 and 24 eggs as small clutches around a communal nesting site in 1985 (Rao and Singh 1992), but had not traced the season when they might have joined the congregation.

(B) Where does the gharial lay maiden clutch of eggs?   A mother gharial with her maiden clutch is smaller in size and lower in the hierarchical order. Such mothers may not find access to better nesting locations or communal nesting stretches used by mother gharials larger in size.

Such territorial behaviour at nesting site is seen from the time the ‘trial pits’ are dug before actual nest holes and laying of eggs. At a communal nesting site, the dominant mother takes possession of all hatchlings; others remain around, and the dominant male also joins in creche guarding. Perhaps it takes a couple of nesting seasons before a maiden mother is able to join the communal site.

 A two-year study in captivity at Ramatirtha in the outskirts of Similipal Tiger Reserve started in 1989 demonstrated strong territorial resource partitioning with mugger crocodiles when they go for basking day after day, or nesting year after year.

Conclusion  The clutch size can be as small as 6. Small clutches with 75% hatching success can be 12. Such small clutches will in all probability be away from communal nesting sites, for behavioural reasons and for reproductive success by the young females in the hierarchal order among gharials.

KEY WORDS: Gharial, Gavialis gangeticus, minimum clutch size, adaptation by young breeding female, hierarchal pattern   

SAND MINING AND AQUATIC FAUNA IN SUSTAINABLE RIVER ECOSYSTEM

I have been hearing protests of some kind or the other about stone mining and sand mining from river beds. The first time I ever experienced such protest was in Katerniyaghat Gharial Sanctuary of Uttaranchal in 1979-80. In 1990s and the first decade of 2000s I heard it from Chambal, and now I hear it from the Mahanadi. Individuals or organizations who have objected to such mining apparently have objected to the unplanned method or noisy interventions in the tranquility of river ecosystems.

Without knowing, who will value these, at this stage I wish to put down some of my observations and thought in this connection. I am doing it mainly because I got the opportunity in the past (1975-1991, in particular) to see and study the aquatic fauna particularly in the rivers Mahanadi and Chambal. The stretch of Mahanadi I studied was (apart from that is upstream of Hirakud into Chhatisgarh) from Hirakud to the coast through Satkoshia Gorge sanctuary of 22 km long and through tributaries like the Luna. My main focus was the Satkoshia Gorge. The stretch of Chambal was within National Chambal Sanctuary (470 km long) from Ranapratap Sagar to Pachhnada (close to the confluence of Chambal-Yamuna and Ganges).. 

In my opinion,

(1) There is a lot of siltation and the river beds have got filled up.

(2) The situation has worsened because of water being taken out of the main river without any or much addition from tributaries.

(3) As a result of (1) and (2) flushing of river bed is not as complete as may have been in the past. I do not have hard data for this. But it is a logical conclusion which the Irrigation department could perhaps substantiate.

(4) For longer life of river as a living-ecosystem, we need water throughout its course, at least in the form of deep pools connected with water flow.

(5) I do not intend to infringe into the economics or other public view of sand mining. As an ecologist and conservationist, I wish my rivers survive as live ecosystems for indicator species like gharial, mugger, turtles and dolphin in Chambal, and any numbers out of these species in my Mahanadi. As a lay man I would say silent dredging and planned sand mining would restore the river bed to a better vibrancy.

TOURIST CARRYING CAPACITY IN SANCTUARIES ON LAND vs. RIVER

Very close to the debate of ‘ecotourism’ in wildlife sanctuaries, it is the mist around ‘Eco-Tourist Carrying Capacity’. The parameters to be considered are different for estimation of the ‘tourist carrying capacity’ for sanctuaries on land vs. sanctuaries on river. Wildlife practitioners need to realize that ‘guidelines’ are very broad-based and cannot address individual cases. If the manager tries to lift the guideline/method from a Tiger Reserve for use in river habitat meant for offering a ‘sanctuary’ for basking crocodiles and turtles, there is bound to be problem.

                                                                                   

For estimation of tourist carrying capacity one guideline from Project Tiger headquarters has been in circulation in different contexts since early 2000s. I have not come across any other written down document in this regard. For more than one reasons I was, however, not comfortable with the method either during my tenure in Similipal Tiger Reserve, or on other occasions when there was a discussion on maintaining healthy trend of tourist inflow. At Similipal, my judgment and intuition kept me stuck for suggesting some of the traditional and workable methods that revolved round aspects like (a) the profile of vehicle used by the visitor, (b) diurnal-timings for tourist-visit, (c) the tourism route, (d) the tourism season, and (e) the numbers of vehicles that may enter on any particular day. The numbers are liable to change on dates like X-mass and New Year. While implementing all these considerations in the field, it involved very rigorous VHF-based tourism monitoring at the personal level by a set of committed higher-level officials from 6AM to 6PM. This was on normal days, when there were no cases like vehicle breakdown or someone from the group missing in the hills.  On unusual days, the staffs keep moving around the reserve the entire night and the supporting wireless stations remain alert all along.  Although the staffs were under pressure due to tourism, regulatory approaches worked well, but we couldn’t write down a fixed code of conduct on ‘tourist carrying capacity’.   In sanctuary management every day was a learning experience. In tourism management the realization was more so.

The extent of disturbance due to tourism is many-fold and highly damaging in river sanctuary than in a land sanctuary. The outline shape of a land sanctuary is tried to be kept extended to all sides; i.e., in order to make the habitat more sustainable the land sanctuaries are usually not strip-like. Here the wildlife remains distributed over the spread-out habitat. While traveling by jeep the impact of tourism cut through the habitat along certain ‘tourism’ routes. Unless one gets down to leave merry-making ‘tourist-foot-prints’, and unless the vehicle is very noisy, in a forest like Similipal, if the jeep makes a journey of 100km with animal visibility over a width of 20meters, then the immediate crude impact is over about 2sq.km.

On the other hand, the shape of a river sanctuary is strip-like. Its water width is further reduced because of sand deposits. The animals protected in a river sanctuary are crocodiles, gharial, turtle, dolphin, otter and other wetland fauna. The reptiles have to come out for basking at water-edge. During the winter season basking is for very long periods during the entire day. In summer, crocodiles come out for night time thermal regulation.

Reduced width of water width means increased disturbance to crocodiles and turtles by navigating boats. While sailing along the river course the tourists tend to disturb the entire visible width of the river habitat and the entire animal population that come out for basking at water edge. Therefore, one cannot think of allowing a fleet of tourist boats one after the other, whatever may be the time gap. Instead, I would suggest the followings:

1. A tourist is not a researcher, but he would like to see gharial and turtle, and also undertake a boat journey. An ‘ecotourist’ may, however, take pride in walking on the banks for observing basking gharials and turtles. Considering these aspects, first of all select a stretch of navigable river the two ends of which can be approached by road. This stretch of river intended for opening to tourists shouldn’t have nesting sites or crocodile/gharial nursery sites. It should have sites used by basking/feeding animals.

2. The tourists are to be taken from camp to the boat-start point in the upstream. From our survey experiences, two boats in the morning and two in the afternoon would constitute a manageable number. It is recommended that the two boats move at a time, allowing no time gap for repeating disturbance to the basking animals. The boats will not be engine-propelled. These should row downstream, keeping to the middle of water course. At the end of the trip the tourists will be brought back to camp by road. There should be no boat-based tourism in the rains or during rising river. Therefore, the boat can return to the starting point either during the mid-day or early evening using a low-noise 10-15HP outboard engine. 

Today’s page is a continuation to what I said in my blog on 24 Feb 2011 about ecotourism without conflict in wildlife conservation. 

I had the opportunity of working in two river sanctuaries--, the Satkoshia Gorge Sanctuary (SKGS) trans-Mahanadi in Odisha during 1975-1981 and the 1990s; and in the National Chambal Gharial Sanctuary (NCS) during 1978, 1982-1985. NCS is along the interstate border of Rajasthan, Madhya Pradesh and Uttar Pradesh. Both the river sanctuaries are essentially sanctuaries for gharial (Gavialis gangeticus) but a variety of other wetland fauna abound in these two sanctuaries.

SKGS has river Mahanadi flowing in the west-east direction. The river cuts the forest into northern and southern portions. After about 30 years’ identity as a gharial/crocodile sanctuary its new identity is as a Tiger Reserve. Tourists coming to SKGS have the range of attractions in the forests as well as along the river. River part of tourism is more sensitive from conservation view point when compared to the forest part. It is because the river is narrow, just 100metres (300 ft) to 230metres (700 ft) wide.

NCS is strictly a river sanctuary. It is over 470km long river Chambal. It does not have any comparable forest on its banks, and as such the sanctuary limits are within a km of water edge to accommodate protection measures to gharial entering tributaries and nallahs during the high flood.

Tourism growth and behaviour are such that very soon most recommendations made in good sense may tend to fall short of ‘conservation ethics’. First, it is because all our visitors are not strict ‘ecotourists’. Second, tourism brings with it several other developments of the society which again may not be conservation-friendly.  Moreover, ‘carrying capacity’ is a concept to be thought about when we intend for ‘sustainable versus full harvest/utilization of resource for a purpose’. In wildlife sanctuaries ‘full utilization of infrastructure or resource for tourism’ is a remote mandate, unthinkable. Hence, in stead of ‘carrying capacity’ it is recommended to have a set of guidelines for regulating tourism without much disturbing the wildlife. That will perhaps be sustainable for both wildlife conservation and tourism industry.