Mugger Crocodiles Research Articles

Mugger Crocodile Crocodylus palustris (Lesson, 1831) predation on Brown Fish Owl Ketupa zeylonensis (J.F. Gmelin, 1788), with notes on existing literature regarding their predation on birds

Several observers have noted that Mugger Crocodiles Crocodylus palustris incorporate birds into their diet, though no authors have reviewed the full range of bird species subject to such predation. In the present study, the first observation of Mugger Crocodile predation on an owl, specifically the Brown Fish Owl Ketupa zeylonensis, is reported. Additionally, the existing literature regarding Mugger Crocodile predation on birds is summarized.

Monitoring the stress physiology of free-ranging mugger crocodiles (Crocodylus palustris) across diverse habitats within Central Gujarat, India.

Animals face several challenges in their natural environment, and to cope with such conditions, they may exhibit contrasting physiological responses that directly affect their overall well-being and survival. In this study, we assessed physiological responses via faecal glucocorticoid metabolite (fGCM) measurements in free-ranging mugger crocodiles inhabiting diverse habitats in Gujarat, India. We sampled muggers within Charotar, a rural area (Zone A) with local people having high tolerance towards the presence of muggers, and Vadodara, a region having both urban (Zone B) and rural (Zone C) areas with high levels of human-mugger conflict (HMC). Further, muggers in Vadodara live in water bodies that are mostly polluted due to sewage disposal from adjoining chemical industries. To measure fGCM (mean ± SEM, ng/g dry faeces) levels in muggers, scats were collected during both breeding (N = 107 scats) and non-breeding (N = 22 scats) seasons from all three zones. We used captive muggers (a focal enclosure) to biologically validate (via capture and restraint) the selected fGCM assay (11-oxoetiocholanolone assay). We showed a significant (P < 0.05) 11-fold increase in fGCM levels between pre-capture (540.9 ± 149.2, N = 11) and post-capture (6259.7 ± 1150.5, N = 11) samples. The validated assay was applied to free-ranging muggers during the breeding season, and Zone A showed significantly (P < 0.05) lower fGCM levels (542.03 ± 71.3) compared to muggers of Zone B (1699.9 ± 180.8) and Zone C (1806.4 ± 243.2), both zones having high levels of HMC with polluted water bodies. A similar contrast in fGCM levels was also observed during the non-breeding season. Overall, the study demonstrated that fGCM levels in muggers varied across habitats, and such variation could be due to a multitude of ecological factors that the species experience in their immediate local environment. Moreover, high fGCM levels in muggers of Vadodara during both breeding and non-breeding seasons may indicate a condition of chronic stress, which could be maladaptive for the species.

BANGLADESH WILDLIFE: A CALL TO ARREST ITS DECLINATION THROUGH REMEDIAL POLICIES AND MANAGEMENT

Bangladesh, located between latitudes 20°34' to 26°38' north and longitudes 88°01' to 92°41' east, is the most densely populated country in the world with 1,252 people per one square kilometre; this is almost three times as dense as its neighbour, India (Ritchie, 2020), other than the island countries like Singapore, and others. So, Bangladesh is not likely to have a large array of wildlife, including both megafauna and macrofauna, and flora. However, because of its very zoo-geographic location in the Indo-Malayan realm of the Oriental Region (Cox, 2001), Bangladesh supports at least three major terrestrial habitats and similar number of aquatic environments. These have allowed the country to have astounding number of wildlife and plants, e.g., about 125 species of Mammals, 718 species of Birds, 2500 species of arthropods and 5700 species of vascular plants. However, it is not satisfied status because already lost few charismatic megafaunas such as, all three species of Asian rhinoceroses, water buffalo, swamp deer, two species of peafowls, swamp partridge, Bhadi Hans (white-winged duck, Khan, 1983a, 1983b, 2003), marsh crocodile, etc. Existing study posits that the country has already lost about 10% of its mammals, 3% birds and 4% of reptile species and an unknown number of amphibians, fishes, and invertebrates as well as plants. Another 14% of animal species are endangered (Khan, 2012). The same may very well be true for the plants.Currently the Forest Department, which has its own forestry policy from as early as 1979, has failed to develop such a policy for wildlife although it is trying to manage the wildlife of the country from the inception of Bangladesh in 1971.The department lacks in right workforce trained in wildlife with proper degree in relevant subjects. A few people that work there does not see progressions in their service carrier.The wildlife conservation policy followed round the world does not conform to the forestry policy of Bangladesh.So, Bangladesh must have a concrete wildlife and its sustainable management policy to conserve the wildlife wealth through creating a proper wildlife department to implement such a policy and save the wildlife from further killing or loss of wildlife through managerial failures or mismanagement.

Observations on cooperative fishing, use of bait for hunting, propensity for marigold flowers and sentient behaviour in Mugger Crocodiles Crocodylus palustris (Lesson, 1831) of river Savitri at Mahad, Maharashtra, India

As far as animal cognition is concerned, in comparison with mammals and birds, reptiles have been underestimated and research in reptilian cognition hasn’t progressed much due to this bias. Though crocodiles are generally stereotyped as lethargic and lacking social interactions except for territoriality, parental care and prey ambush, they demonstrate discrete behavioural repertoire in a variety of situations suggestive of refined cognition. The observations presented here were recorded during a long-term study on Muggers Crocodylus palustris of Savitri River in Maharashtra, and indicate social behaviour of remarkable acuity among Muggers to optimize foraging, which clearly hints at cooperative fishing. Also, on many occasions here, the Muggers were seen to have sticks on their snouts or lay still in the vicinity of floating twigs presumably to lure birds that desperately scouted for nesting material; though only on one occasion the unsuspecting bird was ambushed successfully. Flight initiation distances (FID) of birds that forage and nest in crocodilian habitat have been measured to assess their wariness towards crocodile’s presence. We report the attraction of free ranging Muggers here to the yellow Marigold Tagetes erecta flowers. We also remark on apparent sentience involving a dog that was chased into the river by a pack of feral dogs, the ‘aquatic refugee’ having been seemingly nudged and escorted to safety of the bank by crocodiles. All these behaviours are discussed in the light of previous reports involving other crocodilian species elsewhere, to assess the cognitive faculty of this species.

Factors influencing the habitat selection of Mugger crocodile (Crocodylus palustris) and its conservation threats in the Rapti River of Chitwan National Park, Nepal

Mugger crocodiles (hereafter called muggers) are the apex predator and keystone species in slow flowing freshwater ecosystem. They play an important role in its functioning by distributing nutrients and increasing primary productivity. Muggers have a sympatric distribution with gharials in the Rapti and Narayani River of Chitwan National Park, but more research and conservation attention has been focused on gharials in Nepal. The inadequate availability of information on the occupied habitats of muggers restrict their evidence-based conservation and management. Therefore, we investigated the ecological factors affecting the habitat selection of muggers and its conservation threats in the Rapti River. We conducted a preliminary survey, followed by a detailed habitat survey, conducted in February and March 2022. During the detailed habitat survey, the pre-defined habitat characteristics were recorded at each station spaced at 500 m intervals along the river as well as the locations where muggers were sighted. We used a generalized linear model (glm) under the binomial family with a logit link function to analyze the factors influencing the habitat selection of muggers. The dependent variable was the presence or absence of muggers at sampling points and the independent variables included: river bank aspect, river width, mid-river depth, river bank substrate type, river bank slope, water current, invasive alien plant species, and anthropogenic disturbances. In addition, a relative whole-site ranking method was employed to determine the most prevalent threats to the mugger. During the survey period, we recorded a total of 46 mugger individuals, 71.8% were observed basking and 28.2% were observed submerged in the river. The highest percentage of muggers (39.1%) was observed on the sandy river bank, followed by the grass and forest bank (19.5%), and clay and sandy bank (15%), respectively. Only the river banks with moderate (15–25°) and moderately steep (25–35°) slopes were found to be the significant factors influencing the occurrence of muggers. Fishing and extraction of river materials, and disposal of garbage and solid waste were ranked as the most prevalent conservation threats. For the long-term conservation of muggers in the Rapti River, effective habitat management plans and strategies are required to control illegal anthropogenic activities such as fishing, sand mining, and boulder quarrying. Research on spatio‐temporal partitioning between mugger and gharials is recommended to understand how resources are shared by the species.

Identification of free-ranging mugger crocodiles by applying deep learning methods on UAV imagery

Individual identification contributes significantly towards investigating behavioral mechanisms of animals and understanding underlying ecological principles. Most studies employ invasive procedures for individually identifying organisms. In recent times, computer-vision techniques have served as an alternative to invasive methods. However, these studies primarily rely on user input data collected from captivity or from individuals under partially restrained conditions. Challenges in collecting data from free-ranging individuals are higher when compared to captive populations. However, the former is a far more important priority for real-world applications. In this paper, we used Unmanned Aerial Vehicle (UAV) to collect data from free-ranging mugger crocodiles, Crocodylus palustris. We applied convolutional neural networks (CNNs) to individually identify muggers based on their dorsal scute patterns. The CNN model was trained on a data set of 88,000 images focusing on the mugger's dorsal body. The data was collected from 143 individuals across 19 different locations along the western part of India. We trained two CNN models, one with an annotated bounding box approach, the YOLO-v5l, and another without annotations, the Inception-v3. We used two parameters, True Positive Rate (TPR) and True Negative Rate (TNR), to validate the efficiency of the trained models. Using YOLO-v5l, TPR (re-identification of trained muggers) and TNR (differentiating untrained muggers as ‘unknown’) values at the 0.84 decision threshold were 88.8% and 89.6%, respectively. The trained model showed 100% TNR for the non-mugger species, the Gharial, Gavialis gangeticus, and the Saltwater crocodile, Crocodylus porosus. The performance of the CNN model was reliable and accurate while using only 125 images per individual for training purposes. Inception-v3 underperformed for both the parameters, thus, showing that a bounding box approach (YOLO-v5l model) with background elimination is a promising method to individually identify free-ranging mugger crocodiles. Our manuscript demonstrates that UAV imagery appears to be a promising tool for non-invasive collection of data from free-ranging populations. It can be used to train open-source algorithms for individual identification. Further, the identification method is entirely based upon dorsal scute patterns, which can be applied to different crocodilian species, as well.

Physicochemical assessment of Wetlands and its Impact on Marsh Crocodiles Crocodylus palustris (Lesson, 1831) of Terai Landscape, Uttarakhand, India

Water is the basic life line of all living organism on this planet. The study revealed that the significance of water quality is good at the Terai Arc Landscape (TAL) rivers which passes through the Terai landscape of Kumaun, Uttarakhand, India. Water is essential for drinking, domestic, irrigation and industrial purposes. The Terai Landscape of Uttarakhand is rich in water resources and which is utilizable for all purposes. Rapid industrialization has led to low quality of water due to wastewater flowing in natural wetlands of the area. Water and their ecosystems are major indicators of the strength of forest and aquatic fauna. This was achieved by analyzing 12 water quality parameters from samples collected at 13 study sites between the Kosi and Sharda river stretch of different water bodies on monthly basis for a period of 12 calendar months. The water physicochemical variables are analyzed using standard methods during May 2015 to April 2016 and its assessment is carried out. The 12 parameters included Average depth, Temperature, pH, Transparency (turbidity), Dissolved Oxygen (DO), Total Hardness, Total Alkalinity, Chloride, Nitrate, Fluoride, Total Iron, Phosphate and presence and absence of Coliforms. We observed that the range of contagion, vicinity of pollution sources and water quality of sites suggest that the species is under threatened category in Terai landscape, Uttarakhand. Amongst the 13 sites chosen for assessment, the physicochemical properties of different water bodies in reference to usage of wildlife such as Marsh crocodile, tiger, leopard, elephant, sloth bear and many species of herbivores at present is acceptable.

Assessment of the water quality of Ghodaghodi lake using selected physicochemical parameters

The physicochemical parameters of Ghodaghodi lake were investigated during pre-monsoon ( May, 2018) and Post-monsoon season ( November, 2018). Water samples for physicochemical parameters were collected and analyzed using standard methods. Four different sampling sites (I, II, III, and IV) were studied. Triplicate of water samples were collected from each site of Lake and physico-chemical characteristics, i.e. pH, temperature, depth, dissolved oxygen, total alkalinity, total hardness, conductivity, total dissolved matter, free CO 2 , nitrate and inorganic phosphorous were analyzed. Random sampling method was used. Altogether, 8 quadrats (four paired quadrats) were plotted in each site of the study area per season. Altogether 32 quadrats were laid down per season. Water samples were collected from the depth of 0.5 m within the 1m×1m quadrats. CO 2 , hardness, temperature and depth was also found to be high during pre-monsoon and these parameters have low values during post-monsoon. pH, conductivity, alkalinity, DO and TDS, value (±SD) was found to be high during post-monsoon with value and low during pre-monsoon. The average value of physicochemical parameters studied were water temperature (22.92°C), pH (7.69), DO (3.2 mg/L), electrical conductivity (180.71 μS/cm), TDS (91.43 ppm), Free CO 2 (128.29 mg/L),Total hardness (191.16 mg/L), Total alkalinity (177.41 mg/L), phosphate (0.33 mg/L) and nitrate (0.0.095 mg/L). Very low DO concentrations in lake indicated very stressful conditions for aquatic life forms. This is of great concern especially regarding the conservation of critically endangered gharial, vulnerable marsh crocodile, and many other fish species. The limnological status of the lake estimated in this study is of critical importance to implement management actions for the conservation and better management of Ghodaghodi lake, a wetland of western terai,Nepal.

Ongoing assessment of the Marsh Crocodile (Crocodylus palustris) population in the wetlands of Anand and Kheda Districts, Gujarat, India

Ongoing assessment of the Marsh Crocodile (Crocodylus palustris) population in the wetlands of Anand and Kheda Districts, Gujarat, India

Anecdotal observations of ‘double clutching’ behaviour in captive Mugger crocodiles (Crocodylus palustris)

Abstract Animals modulate their behaviours in accordance with their local environment and in the process, undergo different behavioural and physiological adaptations to better survive in a given ecosystem. One such behaviour that plays an important role in survival and sustenance of a species is the breeding behaviour. In this article, we present anecdotal information on breeding strategies of Marsh or Mugger crocodiles. Mugger crocodiles mostly lay single clutch during a year and have an elongated courtship and mating period lasting for 3–4 months. However, we show anecdotal data covering a period of 2 years for a Mugger crocodile producing double clutches annually under captive conditions. The laying of multiple clutches in captive Mugger crocodiles may indicate higher nutritional status and/or breeding strategies of the females under resourceful conditions. We suggest the need for future work on understanding proximate mechanisms underlying the ‘double clutching’ behaviour of Mugger crocodiles.

Basking Behaviour and Use of Riparian Tunnels by Mugger Crocodiles Crocodylus palustris (Lesson, 1831) of Savitri River at Mahad, Maharashtra, India

This study has recorded observations on maintenance behaviour pertaining to basking and use of tunnels by Mugger crocodiles Crocodylus palustris (Lesson, 1831) of river Savitri at Mahad in the Indian state of Maharashtra. The Mugger shuttles between the land and water guided by a circadian rhythm, primarily to regulate its body temperature. This amphibious reptile was seen to be meeting its thermal preferences by a combination of heat-seeking and heat-avoiding behaviours that largely revolve around immersion in water, basking and retreating in tunnels. The ascendance from water body to bask on dry ground also included intermediate postures taken by the Mugger like pre-basking, surface basking and shallow water basking; and the relative amount of time spent in each of these behaviours varied seasonally. Also, the Mugger crocodiles were seen to excavate separate tunnels on the river banks for purpose of resting and nesting. These observations recorded over a span of nine years are discussed in the context of ethology. The study also documents behaviour of Mugger with conspecifics and other species that share its habitat. It is emphasized that understanding of crocodile behaviour helps in discernment of species-specific natural history, and is also important from the perspective of its conservation management.

Total length and head length relationship in Mugger Crocodiles Crocodylus palustris (Reptilia: Crocodilia: Crocodylidae) in Iran

This study quantifies the morphometric relationship between total length (TL) and head length (HL) for a sample of 53 Mugger crocodiles (43–280 cm TL) in Iran. Across the size range of crocodiles sampled, the relationship was best described by a linear regression (TL= 15.52 + 6.283HL). The average TL/HL ratio was 7.034, which is similar to that reported for other crocodilian species and confirms its usefulness for estimating TL based on HL during population surveys.

A study on the oral and cloacal bacterial flora of Mugger crocodiles (Crocodylus palustris) in the Negour protected area, Iran.

Mugger crocodile is the only crocodile existing in Iran. The present study was aimed to investigate the bacterial flora in oral and cloacal cavities of wild Mugger crocodiles in Negour protected area, Iran. The isolation and molecular characterization of oral and cloacal bacterial flora were performed in 22 Mugger crocodiles captured in Negour protected area, Iran. Ten bacterial species from all oral samples and six bacterial species from all cloacal samples were recovered. The most commonly isolated bacteria in oral samples were Burkholderia contaminans and Lactococcus garvieae, respectively; whereas, in cloacal samples, it was Lactococcus lactis. It is likely that the isolated bacteria would pose a threat to both crocodiles and humans health. It can threaten crocodiles during stressful conditions; while, humans would be susceptible if they are bitten by crocodiles, consume their meat or spend time near their natural environment. This study provides useful information about bacterial diversity which could help to select the most appropriate anti-bacterial when dealing with infections caused by crocodiles.

Morphometry, nutrition and health of the marsh crocodile (Crocodylus palustris) conserved in the Chittagong zoo, Bangladesh

Morphometry, nutrition and health of the marsh crocodile (Crocodylus palustris) conserved in the Chittagong zoo, Bangladesh

&lt;b&gt;Mugger Crocodile &lt;I&gt;Crocodylus palustris&lt;/I&gt; Lesson, 1831 (Reptilia: Crocodilia: Crocodylidae) in river Saberi of Godavari system in southern Odisha, India: conservation implications&lt;/b&gt;

A biodiversity survey was conducted in Koraput District of southern Odisha between August 2014 and July 2017. During the survey, occurrence of Mugger or Marsh Crocodile Crocodylus palustris was ascertained from five localities in a stretch of 23km of river Saberi, a tributary of the Godavari River system. The area is in the Gupteswar proposed reserve forest of Odisha, and forms a boundary with Kanger Ghat National Park of Chhattisgarh State. The geographic region offers possible scope for long term ecological monitoring jointly by wildlife organizations of Odisha and Chhattisgarh in collaboration with Central University of Orissa. For long-term conservation of the species, activities may be initiated with annual monitoring of crocodile populations involving local people, and creating awareness about the Schedule-I status of crocodiles under the Wildlife Protection Act, 1972.

Results of the 2015 Mugger Crocodile (Crocodylus palustris) count at Vadodara, Gujarat, India

&#x0D; &#x0D; &#x0D; &#x0D; This report documents the Mugger Crocodile census conducted on 20–21 January 2015 at Vadodara City, Gujarat. This is a periodic procedure and part of an ongoing study designed to monitor this urban population with the help of public participation. The results show gradual increase in the Mugger populaion within the demarcated stretch of the River Vishwamitri. The night-count numbers indicated the presence of 250 individuals of various sizes (&lt;1 m to &gt; 4 m in total length). Mugger Crocodiles are wild, aquatic, carnivorous animals that have been flourishing in close proximity to humans, allowing for a noteworthy case study of the human-Mugger relationship. However, direct and indirect conflict data from the year 2014 are alarming – 24 documented Mugger attacks (12 of which were fatal) within the state, seven (three fatal) within the city limits, and 48 Muggers of various sizes rescued from the area. These numbers are indicative of a unique, complicated, and delicate relationship between humans and crocodiles as a balance is sought between Mugger conservation and a steadily rising urban population.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D;

&lt;b&gt;Review and analysis of human and Mugger Crocodile conflict in Gujarat, India from 1960 to 2013&lt;/b&gt;

Human-Crocodile conflict (HCC) occurs to varying degrees around the World, and with a number of crocodilian species (CrocBITE 2013). The Mugger or Marsh Crocodile Crocodylus palustris found in Gujarat State is the crocodilian species responsible for conflict with local people. This paper is a compilation of HCC occurring in various parts of Gujarat from 1960 to 2013. A total of 64 crocodile attacks were recorded: 44 (24 fatal &amp; 20 non-fatal) on males, and 20 (9 fatal &amp; 11 non-fatal) on females. By region 52 HCC were recorded in central Gujarat; five in Saurashtra, four in the northern region and three in Kutch; no crocodile attacks were recorded in southern Gujarat. Of the two major river systems in central Gujarat, 41 attacks occurred within the Vishwamitri-Dhadhar River System and 11 in the Narmada system. Most crocodile attacks happened between the months of April and September, peaking in May with 14 attacks. These months are the peak breeding season for the species in Gujarat. The most obvious contributors to HCC are lack of basic facilities in rural areas, poverty, illiteracy and the presence of adult animals close to human settlements and activities. Other contributing factors are lack of preventive measures by the forest department, absence of protocols for mugger crocodile rescue, and haphazard release of problematic animals.

Parasitic fauna of captive mugger crocodiles (Crocodylus palustris) in south India

Coprological samples of captive mugger Crocodiles (Crocodylus palustris) were randomly collected (102 Nos) from Snake Park, Guindy (36 Nos), Arignar Anna Zoological Park, Vandalur (44 Nos) and Amaravathy Crocodile farm (22 Nos) and screened for evidence of parasitic fauna using fecal sedimentation technique. Parasitic fauna evidenced trematode egg, Renifers which were predominant in Snake Park, Guindy and Amaravathy Crocodile farm and nematode eggs, Dujardinascaris sp. in samples from Arignar Anna Zoological Park, Vandalur. Among the study, Dujardinascaris sp. was predominant and mixed infections of Renifers and Ophiotaenia sp. were limited. However Polydelphis sp. was observed only in Amaravathy farm. Renifers and Dujardinascaris sp. were found in mugger crocodiles from all these three locations. No ectoparasites were encountered in mugger crocodiles during this study. Snake Park, Guindy and Amaravathy Crocodile farm had the habit of feeding fishes to this reptile encountered the presence of trematode and cestode eggs in these areas. Captivity provides the condition in such a way that ectoparasites could not be ruled out in this study unlike free-ranging habitat.

Preliminary Inventory of Biodiversity at Ghodahada Reservoir: Conservation of Mugger Crocodile at Ganjam District, Odisha

The existing small population of Mugger crocodile inhabit in south Odisha near Ganjam and Parlakamundai district Border. The main habitats could be classified in two, main natural and artificial habitats. The main natural habitats are the small and large ponds along the main Reservoir, Ghodahada. Most of these ponds have similar characteristics providing suitable habitats for the Mugger crocodiles. Generally, Mugger crocodiles avoid from running parts of the rivers, streams and prefer fairly deep and calm parts of the rivers with suitable vegetation and sandy banks. As the artificial water bodies also play essential support for the Mugger crocodile population. Small and large ponds nearby villages constructed for the rain water storage as well as the dams constructed along the river Ghodahada supposed to be important habitats for the Mugger crocodiles too. The movement of Mugger crocodiles between the habitats is usual recorded behavior in the area. In most habitats the Mugger crocodiles have close contact with local people. Some ponds in border area are supposed to be Mugger crocodile habitats too, and some reports from local people indicating movement between the local habitats. Constructed dams on the main rivers had important effects on the habitats too. 37 species of fish, 8 amphibian 28 reptilian and 46 bird species are the main food resources for the Mugger crocodiles in these habitats which also add the richness to biodiversity of area. Since 2008 Mugger crocodile conservation program was initiated by Berhampur forest department. Latest 2014 census recorded 46 basking Mugger crocodiles and 7 nests were found during the nest survey in small islands/mainland in habitat.

Ecological status and threats of marsh crocodiles (Crocodilus palustris) in Manghopir Karachi

This study represents survey data and reviews the threats and ecological status of Marsh crocodiles (Crocodylus palustris) in the captive habitat of Manghopir Karachi. In Pakistan, only one crocodilian species of Marsh crocodile recorded. The present study on threats and ecological status of Marsh crocodiles was carried out from 2006 to 2009 during which 116 crocodiles were recorded from MP Karachi. The observation revealed that total number of crocodiles were 116 in the studied areas of MP Karachi among them 80 were adult crocodile, 20 were juveniles and 16 were hatchlings. The most people consider them as a serious and potentially dangerous pest and so do not regret their disappearance from their neighborhood. In Pakistan, the concept of utilization of wildlife is still anathema to a large segment of the crocodile population and they can be ranched. Currently the crocodile population is threatened by environmental deterioration, hazard chemicals in water resources, hunting pressure and loss of habitat.