Absence of evidence is not evidence of absence: Knowledge shortfalls threaten the effective conservation of freshwater crocodiles

Somaweera, Ruchira; Brien, Mathew L.; Sonneman, Tracy; Didham, Raphaël K.; Webber, Bruce L.

doi:10.1016/j.gecco.2019.e00773

Cited by 7 publications

(4 citation statements)

References 104 publications

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“…Crocodilians are widely considered as critical components of freshwater ecosystems, but nearly half of the 25 crocodilian extant species are listed as threatened (IUCN, 2017). As an example, Somaweera et al (2019) summarized the existing knowledge on the various direct and indirect threats faced by Crocodylus johnstoni. In addition, a growing body of literature has demonstrated that the growth, reproduction and survival of crocodilians are influenced by the wide array of xenobiotic compounds introduced into the environment by agricultural activities (Beldomenico et al, 2007;Gonzalez-Jauregui et al, 2012;Milnes et al, 2008;Stoker et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Effects of agricultural pesticides on the reproductive system of aquatic wildlife species, with crocodilians as sentinel species

Tavalieri

Galoppo

Canesini

et al. 2020

Molecular and Cellular Endocrinology

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Section: Introductionmentioning

confidence: 99%

Effects of agricultural pesticides on the reproductive system of aquatic wildlife species, with crocodilians as sentinel species

Tavalieri

Galoppo

Canesini

et al. 2020

Molecular and Cellular Endocrinology

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“…, 2020 ). Some significant threats that most crocodile species face include habitat degradation, pollution, poaching and trafficking ( Somaweera et al. , 2019 ).…”

Section: Introductionmentioning

confidence: 99%

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

Desai,

Bhowmik,

Srinivasan

et al. 2024

Conservation Physiology

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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.

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“…They play a crucial role in predator-prey relationships ( Marshall et al 2020 ; D’souza et al 2021 ; Natusch et al 2021 ), are highly potential bio-indicators for the ecosystem including for climate change ( Bickford et al 2010 ; Weatherhead et al 2012 ; Böhm et al 2016 ; Lourenço-de-Moraes et al 2019 ; Zipkin et al 2020 ) and habitat degradation monitoring ( Todd and Andrews 2008 ; Beaupre and Douglas 2009 ; Pike et al 2010 ; Shelton et al 2020 ). Regrettably, snakes as well as lizards receive poor conservation attention compared to other reptile groups such as tortoises and turtles ( Böhm et al 2013 ; Shahirah-Ibrahim et al 2018 ) and crocodiles and gharials ( Martin 2008 ; Somaweera et al 2019 , 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Uneven species occurrence and richness of lowland snakes (Serpentes, Squamata) in Terengganu, Peninsular Malaysia, with new locality records

Syafiq¹,

Badli-Sham²,

Grismer³

et al. 2023

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This study documents information on the composition, diversity, richness, and temporal occurrence of snakes at Sekayu’s lowland forest (SLF), Terengganu, Peninsular Malaysia for the first time. The snakes recorded within the SLF were sampled opportunistically from 2013 to 2019, employing the Visual Encounter Survey method (VES) and L-shape pitfall traps with drift fences. Forty-six snake species from 37 genera belonging to the nine families were recorded, of which 11 were new records to Terengganu. Individual-based rarefaction and extrapolation curves were not reaching asymptote, indicating that additional species can be recorded at the study area. Non-parametric species richness estimators estimated and produced a range between 51 and 57 species. ACE was the best estimator based on the quantitative evaluation. All species showed some variations of occurrence patterns across months. Fourteen species were only encountered once across the sampling years, and interestingly 11 of them were only detected during the rainy season (late October to January). In general, the number of species richness, abundance, and rare species were high during this season. Species richness of snakes is high at SLF but sampling effort should be intensified, especially during these rainy months, to obtain a robust estimated snake species richness in SLF. Terengganu harbor considerably high species richness of snakes with a total of 71 species to date (excluding marine snakes), but snake diversity is still underestimated as only a few localities were surveyed in the past years, primarily at the northern part. Future surveys should be commenced at the central and southern parts of Terengganu to complement the current investigation.

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Absence of evidence is not evidence of absence: Knowledge shortfalls threaten the effective conservation of freshwater crocodiles

Cited by 7 publications

References 104 publications

Effects of agricultural pesticides on the reproductive system of aquatic wildlife species, with crocodilians as sentinel species

Effects of agricultural pesticides on the reproductive system of aquatic wildlife species, with crocodilians as sentinel species

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

Uneven species occurrence and richness of lowland snakes (Serpentes, Squamata) in Terengganu, Peninsular Malaysia, with new locality records

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Absence of evidence is not evidence of absence: Knowledge shortfalls threaten the effective conservation of freshwater crocodiles

Cited by 7 publications

References 104 publications

Effects of agricultural pesticides on the reproductive system of aquatic wildlife species, with crocodilians as sentinel species

Effects of agricultural pesticides on the reproductive system of aquatic wildlife species, with crocodilians as sentinel species

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

﻿Uneven species occurrence and richness of lowland snakes (Serpentes, Squamata) in Terengganu, Peninsular Malaysia, with new locality records

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Uneven species occurrence and richness of lowland snakes (Serpentes, Squamata) in Terengganu, Peninsular Malaysia, with new locality records