Breeding performance of Indian Sarus Crane Grus antigone antigone ...

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Handbook of the Birds of India and Pakistan, Compact Edition. Oxford University Press, Bombay.Google Scholar. Borad C.K., Mukherjee A. and Parasharya B.M. ...
Biodiversity and Conservation 11: 795–805, 2002.  2002 Kluwer Academic Publishers. Printed in the Netherlands.

Breeding performance of Indian Sarus Crane Grus antigone antigone in the paddy crop agroecosystem C.K. BORAD*, AESHITA MUKHERJEE, S.B. PATEL and B.M. PARASHARYA AINP on Agricultural Ornithology, Gujarat Agricultural University, Anand 388 110, India; * Author for correspondence (e-mail: chandresh-borad@ yahoo.com; fax: 191 -2692 -61076 /61520) Received 16 October 2000; accepted in revised form 17 May 2001

Key words: Breeding performance, Conflict, Conservation, Grus antigone, Paddy crop agroecosystem, Sarus Crane Abstract. The breeding performance of the Indian Sarus Crane Grus antigone antigone Linn. was studied in the agricultural landscape of Gujarat, India during 1996. Detailed records of a total of 22 nests were compiled from egg-laying till fledging. Eleven clutches (50.0%) produced at least one chick. Ten clutches (45.45%) were destroyed due to various mortality factors, and one clutch (4.50%) failed to hatch. Of the 10 pairs whose clutches were destroyed, at least four renested. Renesting in the wild was reported for the first time. Egg destruction was mainly due to flooding (12.20%), predation (21.95%) and conflicts with farmers (14.64%). Predation accounted for 31.58% of chick mortality. The egg and chick mortality factors identified were unique to the agricultural ecosystem. The number of chicks that hatched and of chicks fledged per nest did not differ significantly in different microhabitats. Hatching success was higher in non-cultivable agricultural marshland (68.18%) compared to paddy cultivated marshland (38.48%), mainly due to human disturbance and higher predation risk. Overall breeding success was 19.51%. Juveniles comprised only 8.96% of the total number of Sarus Cranes sighted during the post-breeding period. One of the causes of poor breeding performance in the agricultural landscape was increasing conflict with the farmers, who suffer economic loss due to nesting in the crop field. If compensated, farmers may help in Sarus Crane conservation efforts.

Introduction The Indian Sarus Crane (Grus antigone antigone Linn.) is considered a globally threatened species due to a rapid decline in its population size and shrinkage in its range of distribution (Meine and Archibald 1996). It is chiefly distributed in a few northern states of India. Its density is greater in Gujarat, eastern Rajasthan and the Gangetic plain than elsewhere, decreasing towards the south in a diagonal line from Surat (Ali and Ripley 1983). Gole (1989) revealed that it has become very scarce over larger parts of Bihar and Madhya Pradesh and only 13 000 Sarus Cranes exist in India. The Sarus Crane has survived in the agricultural landscape of Gujarat due to cultural heritage of the local people and ability of the species to track habitat changes (Borad et al. 2001a). A few qualitative studies on the breeding ecology of the Sarus Crane have been carried out in the recent past (Walkinshaw 1973a; Desai 1980; Ali and Ripley 1983; Gole 1987, 1989, 1991; Kulshrestha and Vyas 1989; Parasharya et al. 1989, 1996a;

796 Singh and Khan 1989; Vyas and Kulshreshtha 1989; Iqubal 1992; Ramachandran and Vijayan 1994). However, quantitative studies of breeding performance in particular areas have been lacking. Several threats are thought to account for the Sarus Crane population decline (Gole 1989, 1991; Parasharya et al. 1989, 1996a; Muralidharan 1992; Ramachandran and Vijayan 1994). In Gujarat, distribution of the Sarus Crane is largely in the agricultural landscape and is positively correlated with area under paddy cultivation and canal irrigation (Parasharya et al. 1989; Mukherjee et al. 2002); the species is traditionally protected and never molested. Nevertheless, conflict with farmers is considered a major factor behind its population decline in the Kheda district of Gujarat (Parasharya et al. 1989, 1996a). To quantify this conflict and its impact on the population, and to provide information for a management strategy to conserve the Sarus Crane in an agricultural landscape, we undertook a detailed study of the breeding performance of the Sarus Crane in this agricultural landscape.

Methods Study area The breeding season of the Sarus Crane in our study area extended from the first week of August to the first week of October in 1996, with a peak period during the last week of August and the first 2 weeks of September. The study was mainly concentrated in Matar tahsil in the Kheda district, Gujarat. Total rainfall in this area was 856.6 mm over the year 1996. Most of this fell in the period from June to September. The Matar tahsil is located at latitude 228309–228519 N and longitude 728329–728499 E (Figure 1). The total area of Matar tahsil is 577 km 2 , of which 426.04 km 2 is cultivable land. The paddy rice Oryza sativa L. is the main crop, occupying 51.02% of the cultivable land during the monsoon season in Matar tahsil. Agriculture in the study area is dependent on canal irrigation. Survey and monitoring In our study area’s paddy crop agroecosystem the nesting sites of Sarus Cranes were broadly classified as (I) agricultural marshland and (II) non-agricultural marshland. These habitats were further classified into seven microhabitats on the basis of hydrological, topographical and economic features of the microhabitat. These are (I): (1) paddy field bund (permanently fallow narrow bund of land surrounding the field), (2) standing paddy crop, (3) marshy agricultural waste land, (4) Khettalavadi (low-laying area within agricultural marshland which was not suitable for cultivation. To exploit naturally accumulated water as well as to prevent cultivable land converting into wasteland such area is embanked with an earthen bank), (5) canal seepage; (II): (6) reservoir and (7) village pond. Our study of the breeding performance of the Sarus Crane was carried out from July to December 1996. While moving through the study area on different routes

797

Figure 1. Map of the study area.

(Figure 1), the vehicle was driven at a speed of 15–20 km / h and both sides of the road were thoroughly scanned to locate the cranes and their nests. Binoculars (10 3 50) and a telescope (20 3 80) were used at intervals to maximize the scanning area. Bird movement during scanning provided evidence of nesting and prompted us to search for the second bird. In most cases, the second bird was found in the vicinity, attending the nest. Whenever we found a nest, the breeding status of the observed pair was determined through close examination of the site. Additional information about nest, eggs, and adult birds was gathered by interviewing local people. All eggs were marked. All the nests were visited at least once a week until the family left their nesting territory. The number of eggs, number of chicks, parental activity, and nest condition were noted during every visit. The number of eggs hatched divided by the total number laid provided a measure of hatching success (expressed in percentage). Young birds attaining the height of their parents and confirmed freeflying were considered fledged. The number of young birds divided by the total

798 number of eggs laid provided a measure of breeding success. Various factors responsible for destruction of eggs or mortality of chicks were listed. We surveyed the study site in late December and early January 1997 to confirm breeding performance of the preceding season. Harvest of the paddy crop in November left the habitat open, which facilitated the sighting of cranes. All the sightings were carefully categorized as: a pair without juvenile; pair with one juvenile; pair with two juveniles; single adult; or adult and juveniles in flock. Adults and juveniles were distinguished on the basis of their crown color. The crown color of juveniles (maximum age 4 months) was dull brick red (without a bald area), whereas that of adults was dark red with a bald patch on top.

Results Detailed records for a total of 22 nests were maintained from egg-laying until fledging. At least one chick hatched from 11 (50.0%) of the clutches. Ten clutches (45.45%) were destroyed due to various factors (Table 1). In one clutch (4.50%), both eggs failed to hatch. Out of the 10 pairs whose clutches were destroyed, at least four pairs renested. The breeding performance of renesting pairs was calculated separately, and such cases are not included here.

Table 1. Breeding performance of Sarus Crane (n 5 22 nests). Particulars I. Nest 1. Total nests 2. Nest where clutch destroyed 3. Nest with at least one chick 4. Nest where clutch failed to hatch 5. Renesting where clutch destroyed II. Egg 1. Total eggs laid 2. Egg destruction a. Shifting b. Destroyed by farmer c. Flooding d. Predation e. Failed to hatch f. Unknown reason III. Chick 1. Total hatched 2. Chick mortality a. Predation b. Unknown 3. No information 4. Fledged IV. Overall breeding success a

Renesting cases deducted from further calculation.

No.

%

22 10 11 1 4a

45.45 50.00 4.55

41 22 5 1 5 9 2 0

53.66 12.20 2.44 12.20 21.95 4.87

19 6 6

46.34 31.58 31.58

5 8

26.31 42.11 19. 51

799 Egg destruction Initially, 41 eggs were recorded in 22 nests. In 19 nests the clutch size was two. In the other three nests, there was only one egg from the first date of observation until the last observation. Egg destruction was quite heavy (53.66%), owing to several factors. Relative contributions of various factors attributing to egg destruction are given in Table 1. The farmers of Gujarat do not molest Sarus Crane and its egg. However, to avoid damage to the crop by a nesting pair in the form of uprooting plants as nest material, farmers preferably shift the nest with eggs or only eggs to uncultivated area. A total of six eggs from four nests were destroyed due to egg shifting or destruction by the farmers. In three nests, whose eggs had been shifted over 400 m distance, the Sarus Crane did not accept the eggs at the new site but deserted them. The Sarus Cranes were highly sensitive to such disturbances. Predation was a major threat to eggs, accounting for 21.95% of total egg loss. Predation, especially by the Jackal Canus aurius, was the most important mortality factor. Although we did not observe jackals destroying eggs, farmers considered jackals as the main culprit. The House Crow Corvus splendense was an opportunistic predator. Due to ongoing farm operations, incubating cranes were disturbed and compelled to leave their nests. At this time crows were able to quickly land on the nest and destroy the eggs. The crow (Ramachandran and Vijayan 1994) and jackal (Walkinshaw 1973a) have been reported as predators of Sarus Crane eggs and adults at Keoladeo National Park, Bharatpur. Other mortality factors noted in the present study are unique to the paddy crop agroecosystem. In response to flooding, nesting pairs attempted to raise the nest platform by adding fresh nest material. However, when the area was suddenly flooded, the nests were submerged and eggs were drowned. Egg loss due to flooding was 12.20% of the total. In one nest, both eggs failed to hatch. We do not know the reason for hatching failure, but the cranes were observed incubating them for 43 days. Since detailed studies of the breeding ecology of the Sarus Crane have not been conducted until now, there are no other reports of hatching failure and its causes. However, hatching failure due to infertility has been reported in Sandhill Cranes Grus canadensis (Walkinshaw 1973b) and other crane species. Chick mortality Out of 41 eggs laid, only 19 (46.34%) hatched. Hatching success in this agroecosystem was comparable to that reported recently in Keoladeo National Park (Ramachandran and Vijayan 1994). Six chicks (31.58%) certainly died due to predation (probably by jackals). The fate of five other chicks (26.31%) could not be determined, as the breeding pairs and their chicks disappeared from the nesting site 15–20 days after hatching. It is generally observed that parents and their chicks remain around the nest site until the chicks become independent and free-flying by mid-November (Parasharya et al. 1989; Ramachandran and Vijayan 1994). In this

800 case, we do not know whether the Sarus Crane families moved far from the nesting site due to disturbances. A few pairs remained around the nest site even after losing their chicks due to predation. We believe that in five cases, the chicks and their parents left their territory and, hence, could not be traced. We are certain that at least eight chicks (42.11%) survived until they became independent and free-flying. Survival of eight chicks out of 41 eggs resulted in a 19.51% breeding success rate. Breeding performance in different microhabitat The average clutch size was two and did not differ among microhabitats (Table 2). The mean number of chicks hatched per nest was not statistically significant among microhabitats; however, the value was lower in microhabitat-1 (paddy field bund) compared to other microhabitats. The hatching success was higher in non-cultivable agricultural marshland (68.18%) compared to paddy cultivated marshland (38.46%). The number of chicks surviving until fledging was the same in all the microhabitats. The clutch size did not differ among the microhabitats because all observed microhabitats fall under agricultural ecosystem. The number of chicks hatched and number of chicks fledged per nest were lower in paddy field compared to marshy agricultural wasteland and khet-talavadi. Paddy crop areas were highly disturbed compared to other microhabitats. The breeding performance of cranes within paddy fields was very poor compared to non-cultivable marshland. Out of the total of 10 clutches destroyed, seven were in paddy crop area. Incidents involving conflicts with farmers, flooding, predation, and pesticide poisoning were more prevalent in paddy crop area than the other microhabitats. Later in November, the risk of chick predation increases with progress in harvesting, as chicks suddenly lose their shelter of vegetation cover. We came across one case of pesticide poisoning where a chick died, and later on there was a Table 2. Breeding performance of the Indian Sarus Crane in different microhabitats of the paddy crop agroecosystem. Microhabitat

1 2 3 4 5 F value df CD at 5% C.V. (%) Test

Clutch size

No. hatched

No. fledged

n

Mean

6 S.E.

n

Mean

6 S.E.

n

Mean

6 S.E.

12 1 4 4 3

2.00 2.00 2.00 2.00 2.00 0 3.19 0 0 NS

0.00 0.00 0.00 0.00 0.00

12 1 4 4 3

0.67 2.00 1.50 0.75 2.00 2.19 3.18 NS 87.0 NS

0.22 0.00 0.43 0.41 0.00

10 1 4 4 1

0.30 1.00 0.50 0.50 0.00 0.20 2.15 NS 163.98 NS

0.14 0.00 0.25 0.43 0.00

Microhabitat deducted from ANOVA when n , 2. I. Agricultural marshland: (A) paddy cultivated area: 1. field bund, 2. within standing crop; (B) non-cultivable land: 3. marshy wasteland, 4. Kheat-talavadi, 5. seepage canal. II. Non-agricultural marshland: 7. reservoir, 8. village pond. NS – not significant.

801 report of poisoning of an entire family (2 adults 1 1 juvenile). Poisoning of Sarus Cranes feeding in agricultural area near Keoladeo National Park (Muralidharan 1992; Ramachandran and Vijayan 1994) and in the Kheda district, Gujarat (Parasharya et al. 1989) has been documented. After consuming pesticide-treated grains, at least 15 cranes died around Keoladeo National Park, Bharatpur and 13 cranes at Pali near Jodhpur in Rajasthan state during November and December 2000 (Times of India Daily, Indiafile, 27 December 2000). Individual incidences of poisoning go unnoticed, but the mass poisoning reflects the severity of the problem. Khet-talavadi, canal seepage, and marshy wasteland are very important breeding sites for cranes (Borad et al. 2001a). The farmers have a conflict with the Sarus Crane only because of its nesting activity within the crop, causing economic loss (Borad et al. 2001b). Once alternative nesting sites become available, its nesting frequency in paddy fields will be reduced. Such microhabitats exist in today’s agricultural landscape due to poor management. Uniform distribution and maintainence of such non-cultivable marshland would provide near-natural habitat conditions for the cranes. This would ensure greater breeding success for the cranes and reduce conflict with farmers. Rodenhouse et al. (1993) have emphasized the importance of the uncultivated areas within agricultural landscape for enhancing neotropical migrants. Breeding performance based on post-breeding count A total of 201 Sarus Crane were sighted, of which 122 (60.7%) were in family groups and 78 (38.8%) were in flocks. One (0.5%) Sarus Crane was seen alone. Of 201 Sarus Cranes, 18 (8.96%) were juveniles and 183 (91.04%) were adults. The adult-to-juvenile ratio was 1:0.09, indicating an 8.96% recruitment rate in the population. The percentage of juveniles in the population of the Kheda district during 1989–1996 ranged from 7.9 to 18.9% (Parasharya et al. 1996a), while Gole (1991) estimated 12% juveniles in the population and concluded that the majority of the Sarus Cranes are not successful in rearing their offspring to maturity. Of the Sarus Cranes seen in family groups, 70 adults (35 pairs) were without juveniles; 32 adults (16 pairs) were with one juvenile; and 2 adults (1 pair) were with two juveniles. Among the successful breeders, 5.88% of the pairs had two chicks; 94.12% could raise only one chick. It has been established that Sarus Cranes usually raise only one chick (Gole 1989, 1991; Parasharya et al. 1989, 1996a), although the reasons are not yet known. Of the total of 52 pairs recorded, only 17 pairs (32.69%) raised chicks. The large number of pairs without a single juvenile indicates that these potential breeders failed to raise progeny for one reason or another. Parasharya et al. (1989, 1996a) stated that such potential breeding pairs (without juvenile) move as a separate family and do not join the flock until late January. The breeding failure of such potential breeders in agricultural landscapes is a matter of serious concern. One important factor leading to breeding failure in the paddy crop fields was conflict with the local farmers. Many of the farmers actually scared away the territorial pair to safeguard their crop. The problem of Sarus Crane’s conflicts with farmers seems to be

802 widespread, as Gole (1991) reported destruction of nests in paddy fields in northern Maharashtra. Of the total of 78 categorized Sarus Cranes sighted in the flock, there was not a single juvenile. This result is consistent with data presented by Parasharya et al. (1989, 1996a) and further supports their finding that successful breeders do not join the flock immediately after breeding. Renesting after destruction of first clutch A total of 10 clutches were destroyed during the incubation period (Table 3). Of these 10 breeding pairs, two pairs left the original nest site (territory) and hence we do not know whether they made any renesting attempts. Four pairs remained around their original nest site but did not attempt to renest. The remaining four pairs (40.4%) renested very close to the original nest site. Three nests were built within 15–100 m of the original nest site. The fourth nest was built 700 m away from the original nest site because suitable nesting habitat was available only at that distance. On one side of the original site there was human habitation and on the other side water depth was too high, compelling the pair to move to a more distant site. All four new nests were built within 10–20 days after destruction of the first clutch. Renesting attempts were recorded in August, September and October. A total of five eggs was observed in three nests, whereas in one nest clutch initiation was not confirmed. Four chicks hatched out successfully and two survived until the age of fledging. Since there are no detailed studies of the breeding ecology of Sarus Crane in the wild, there are no previous reports of renesting. However, many crane species are known to do so (Mirande et al. 1996). The Common Crane G. grus lays second and third clutches after destruction of the first one (Neumann 1986–1987). Removal of one egg from a clutch of two to stimulate the laying of more eggs is a common technique used in captive breeding programmes of cranes (Mirande et al. 1996). The Table 3. Second nesting attempt by the Indian Sarus Crane. Details

1. First clutch lost due to 2. Second attempt (DAD) 3. Date of re-nesting 4. Distance from original nest (m) 5. Microhabitat 6. Clutch size 7. Total eggs recorded 8. Egg destruction 9. Chick hatched 10. Chick mortality 11. Young fledged

Nest number IB

3B

7B

10 B

Shifting 12 30 / 8 15 1 NI 1 0 1 0 1

Flood 13 28 / 9 700 1 2 2 1 1 1 0

Flood 10 16 / 9 70 1 NI NI NI NI NI NI

Shifting 20 1 / 10 100 2 2 2 0 2 1 1

DAD – day after destruction of first clutch; NI – no information; S – shifting, F – flooding.

803 relaying capacity of Sarus Cranes in the wild is now established by this study. If the complete clutch is collected, particularly if the eggs are fresh, the Sarus Crane will renest immediately. This may not affect the production of the number of juveniles in the wild, and at the same time additional juveniles can be reared in captivity (G. Archibald, personal communication).

Discussion Agricultural ecosystem is highly productive with respect to grains, green fodder or invertebrate prey which ensures food to birds of diverse food habits (O’Connor and Shrubb 1986; Dhindsa and Saini 1994; Borad et al. 2000). In western India, at least 260 bird species have been recorded in intensively cultivated areas (Parasharya et al. 1996b). Hence, a large number of bird species utilizing agroecosystem are directly influenced by agriculture. Agriculture is implicated in the decline of several bird species currently listed as threatened or endangered or that are candidates for listing (O’Connor and Shrubb 1986; Rodenhouse et al. 1993). Population decline of several bird species in India has been attributed to agricultural activities (Parasharya et al. 1996a; Rahmani 1996; Sankaran 1997; Javed et al. 1999). The egg destruction and chick mortality factors identified in this study are unique to the paddy crop agroecosystem. The most serious factor was conflict with the farmers, mainly due to nesting and feeding activity in crop field causing damage to the crop (Borad et al. 2001b). Crane–farmer conflicts as a factor in crane population declines was reported earlier from the same study site (Parasharya et al. 1989, 1996a). In the present study, impact of conflict on breeding success is quantified. The preference for paddy fields (which are temporary wetlands) for feeding and breeding is quite obvious which fulfil the basic requirements. On the other hand, natural marshlands either do not exist or have been degraded. The cranes have adapted to this situation and survived well. Cultural traditions and the sympathetic attitude of the farmers towards cranes have enabled the cranes to survive at a high density in the Kheda district, Gujarat. Even Gole (1989) did not find such a high density of cranes in other parts of the country. As a matter of fact, no one molests Sarus Cranes in Gujarat state or elsewhere in the country. However, the harmony between cranes and farmers is slowly breaking down, as evidenced by this study. Increasing economic pressure, decreasing land holdings (as a result of increasing human population), and the modernization of agriculture are the factors responsible for increases in crane–farmer conflict. Such conflict is likely to increase and become a more serious threat to the survival of the Sarus Crane, which has to be minimized. Besides the few small measures mentioned above, greater public awareness through educational programmes has important potential. Enforcement of legislation is considered to be one important factor for crane conservation in Europe (Prange 1995). Education of farmers through religious teaching had been suggested by Parasharya et al. (1996a). However, wisdom and the realities of life are two different extremities. In the present study we have clearly identified the factors behind the conflict. We believe that if the economic loss of the

804 farmer can be compensated, conservation in the agricultural landscape of Gujarat may not be a difficult task. Despite a high rate of farmer conflict, the overall breeding success of the Sarus Crane in this agricultural landscape was as high as that reported in Keoladeo National Park, a protected area. It seems that legal protection is not the only, or the most necessary, action needed to ensure to survival of the species. Survival of the Sarus Crane in the agricultural area in Gujarat is chiefly attributable to the religious and cultural heritage of the region. We met several farmers who refused to show us the nest in their fields, as they were afraid that we might disturb the nesting cranes. If this religious and cultural heritage of respect can be maintained, the Sarus Crane can survive within the paddy crop agroecosystem and people and cranes may continue to co-exist.

Acknowledgements We are thankful to Dr D.N. Yadav for providing us with laboratory facilities and moral encouragement throughout the period of study. The authors are also grateful for the kind help extended by Dr P.R.Vaishnav in statistical analysis of the data. We are grateful to Mr N.A. Thakor and P.D. Chavda for their field assistance. This study was financed by the Indian Council of Agricultural Research (ICAR), New Delhi.

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