Adam Britton | Charles Darwin University (original) (raw)
Papers by Adam Britton
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Marine and Freshwater Research, 2016
Saltwater crocodiles (Crocodylus porosus) are potentially dangerous to humans, yet they have majo... more Saltwater crocodiles (Crocodylus porosus) are potentially dangerous to humans, yet they have major cultural value to many people in Timor-Leste. Recent increases in attack risk are influencing traditional attitudes, threatening culls of remaining wild crocodile populations. To understand patterns that may assist mitigation, we compiled attack records for the period of April 2007 to April 2014, using the CrocBITE online database. Recorded attacks (n=45) showed a high fatality rate (82.2%), the majority (77.8%) being recorded since 2010. The highest proportion of attacks (46.7%) occurred in southern coastal wetlands suited to crocodiles, areas representing major sources of food, livelihoods and ecosystem services (i.e. fisheries, timber, coastal protection) for locals. Subsistence fishing posed the highest attack risk, particularly from September to February when food security is low. Attacks matched gender roles (most victims were males, the primary fishers) and demographic patterns ...
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ABSTRACT
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Thesis (Ph. D.)--University of Bristol, 1996.
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Attacks on humans by crocodilians have been documented reasonably well in developed countries in ... more Attacks on humans by crocodilians have been documented reasonably well in developed countries in the last few decades. Conversely, attacks in developing countries are typically poorly documented despite those countries holding the highest frequencies of crocodilian attacks. Here we present the results of an analysis of 1237 crocodilian attacks resulting in 674 fatalities worldwide for the period of January 2008 through July 8th, 2013. Attacks were recorded from 15 crocodilian species and fatal attacks were recorded from 7 of those 15 crocodilian species. 494 attacks resulting in 285 fatalities were recorded for Crocodylus porosus (problem areas identified for the species include East Timor, Sumatra and East Kalimantan of Indonesia, Sarawak of Malaysia, Orissa of India, and coastal Sri Lanka), 428 attacks resulting in 309 fatalities for C. niloticus, 98 attacks resulting in 50 fatalities for C. palustris (mostly from India, particularly within Gujarat state), 69 attacks resulting in ...
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As the country with the highest number of recent attack reports and very little crocodile populat... more As the country with the highest number of recent attack reports and very little crocodile population data, Indonesia is a perfect example of how CrocBITE can be used as a tool to help inform crocodilian conservation and management. Indonesia is a large, heavily populated nation composed of 34 provinces over an archipelago of 17,508 islands. There are currently four recognized crocodilian species present within Indonesia- the saltwater crocodile, Crocodylus porosus, the Siamese crocodile, C. siamensis, the New Guinea freshwater crocodile, C. novaeguineae, and the Malayan/false gharial, Tomistoma schlegelii. During the January 1st, 2007 through June 6th, 2014 period we recorded 279 crocodilian attacks resulting in 139 deaths in 27 of the 34 provinces. Attack reports were acquired almost entirely from online news reports, the vast majority of which were reported solely in the Indonesian language. The majority of attacks and deaths were attributed to C. porosus (268 attacks resulting in...
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Attacks on humans by crocodilians have been documented reasonably well in developed countries in ... more Attacks on humans by crocodilians have been documented reasonably well in developed countries in the last few decades. Conversely, attacks in developing countries are typically poorly documented despite those countries holding the highest frequencies of crocodilian attacks. Here we present the results of an analysis of over 600 crocodilian attacks worldwide for the period of 2008 through 2011. Attack data were compiled from a number of sources including online media reports, local wildlife officials, crocodilian experts, and relevant recent publications.
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ECOS, 2014
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Herpetology Notes, Jan 25, 2014
Although arboreality in extinct crocodilians is frequently suggested, the climbing abilities of e... more Although arboreality in extinct crocodilians is frequently suggested, the climbing abilities of extant crocodilians have never been discussed in any detail in scientific literature. We present an overview of published and anecdotal information on climbing in extant crocodilians, as well as original observations on four species representing two crocodile genera. These data suggest that climbing behaviour is common among crocodilians and might have multiple functions. The fact that at least some extant crocodilians are capable of climbing arboreal vegetation despite lacking any obvious morphological adaptations
for arboreality must be taken into account by paleontologists trying to elucidate behavioural clues from the morphology of
fossil taxa.
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Wildlife Research, 2013
Context.Spread of the invasive cane toad (Rhinella marina) across northern Australia is of concer... more Context.Spread of the invasive cane toad (Rhinella marina) across northern Australia is of concern. Predator species, including the freshwater crocodile (Crocodylus johnstoni), are susceptible to cane toad toxins when ingested. Upstream populations of freshwater crocodiles are smaller than downstream counterparts because of limited resources. We measured the impact of cane toad arrival on densities of these upstream populations.
Aims.Our aim was to determine whether the influx of cane toads had a negative impact on populations of upstream
‘stunted’freshwater crocodiles.
Methods.Population surveys for crocodiles were conducted in three upstream creek systems, using day- and night-based
survey methods, before the arrival of cane toads in the area. These surveys were repeated under similar conditions following the arrival of cane toads, to compare the distribution and densities of freshwater crocodiles and, hence,measure the impact of cane toads.
Key results. There were significant declines in crocodile density at two survey sites following the arrival of cane toads, and
we found dead crocodiles and cane toad carcasses with crocodile bite marks. The third site showed no change in density. There was a decline in mean density across all sites from 3.0 crocodiles km–1 to 1.1 crocodiles km–1 following the arrival of cane toads.
Conclusions. There was an overall decrease in crocodile densities and a reduction in distribution following the arrival of
cane toads into the survey area. Dead crocodiles and evidence of their having eaten cane toads strongly suggest that these declines were caused directly by the arrival of cane toads into the area. One site showed no apparent change other than an increase in wariness, which may reflect the distribution of available feeding and shelter resources among the three sites.
Implications.These results suggest that upstream freshwater crocodile populations are highly susceptible to cane toad
toxins, and that impacts on their population can include local extirpation. Considering their morphological and possibly
genetic distinctiveness, the loss of these unique populations is of conservation concern.
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Journal of Zoology, 1997
Flight performance and echolocation behaviour of the pond bat, Myotis dasycneme (Boie, 1825), wer... more Flight performance and echolocation behaviour of the pond bat, Myotis dasycneme (Boie, 1825), were investigated over canals and a lake in the Netherlands. Multi-flash stereophotogrammetry, linked with synchronous recording of echolocation calls, was used to reconstruct the three-dimensional flight paths of bats and to correlate flight behaviour with changes in pulse emission during echolocation. Echolocation calls during commuting flight at the canal were sigmoidal in structure, with an initial steep frequency modulated (FM) sweep followed by a more shallow sweep, ending with a second, rapid FM sweep. Similar calls were produced during the search phase of foraging, though longer duration quasi-CF (constant-frequency) calls, with longer interpulse intervals and much reduced initial and final FM sweeps, were produced by bats hunting over a large lake. Overall, calls were generally lower in frequency, with significantly longer pulse durations and interpulse intervals, compared with those of smaller trawling Myotis bats. Flight speeds were compared with predicted optima from aerodynamic models. Commuting bats exceeded predicted maximum range speed, which was considerably higher than that noted for other smaller species of trawling Myotis. Flight speed was significantly higher closer to the roost, at a narrower canal site. A negative correlation between wingbeat frequency and flight speed, and a facultative 1: 1 link between pulse emission and wingbeat during search phase were established. During commuting, the bats flew at a height above that which would normally confer substantial power savings through ground effect. It is argued that, by flying at a lower height, bats would compromise commuting speed. Echolocation calls produced during attempted prey capture were remarkably similar in design to those produced by those other Myotis species that forage in a similar fashion. Prey was detected at 2 m, and reaction distance was 1.8 m. Evidence of a physiological limit on pulse duration and interpulse interval during prey capture is presented. Overlap of emitted pulse and received echo may degrade the performance of echolocation in many bats, and overlap is generally avoided in M. dasycneme except perhaps when the bat is very close to the prey item.
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The Australasian Bat Society Newsletter, Apr 2012
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Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2006
We employed a spectroscopic assay, based on the hemolysis of sheep red blood cells (SRBCs), to as... more We employed a spectroscopic assay, based on the hemolysis of sheep red blood cells (SRBCs), to assess the innate immune function of saltwater and freshwater crocodiles in vitro. Incubation of serum from freshwater and saltwater crocodiles with SRBCs resulted in concentration-dependent increases in SRBC hemolysis. The hemolytic activity occurred rapidly, with detectable activity within 2 min and maximum activity at 20 min. These activities, in both crocodilian species, were heat sensitive, unaffected by 20 mM methylamine, and completely inhibited by low concentrations of EDTA, suggesting that the alternative serum complement cascade is responsible for the observed effects. The hemolytic activities of the sera were inhibited by other chelators of divalent metal ions, such as phosphate and citrate. The inhibition of SRBC hemolysis by EDTA could be completely restored by the addition of 10 mM Ca2+ or Mg2+, but not Ba2+, Cu2+ or Fe2+, indicating specificity for these metal ions. The serum complement activities of both crocodilians were temperature-dependent, with peak activities occurring at 25–30 °C and reduced activities below 25 °C and above 35 °C.
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Journal of The Acoustical Society of America, 2010
ABSTRACT Sound production in reptiles is generally limited in scope, yet crocodilians have develo... more ABSTRACT Sound production in reptiles is generally limited in scope, yet crocodilians have developed a modest repertoire of vocal and non-vocal acoustic signals to convey a range of different information. This ability is perhaps less surprising considering that their Archosaur heritage is shared with dinosaurs and birds, and basic similarities to avian bioacoustics are apparent. An overview is presented of sound production and reception in crocodilians, the sound characteristics and repertoire of known signals, and the important role that these signals play in crocodilian behavior. The evolution of bioacoustics in this group is touched upon, based on biological and behavioral evidence between species.
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Journal of Vertebrate Paleontology, 2005
... schlegelii S. Volia athollandersoni Crocodylus niloticus -7 Crocodylus acutus - Crocodylus po... more ... schlegelii S. Volia athollandersoni Crocodylus niloticus -7 Crocodylus acutus - Crocodylus porosus Crocodylus johnstoni Crocodylus mindorensis Crocodylus novaeguineae Crocodylus siamensis Deinosuchus sp. Baryphracta ...
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Wilderness & Environmental Medicine, 2005
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Marine and Freshwater Research, 2016
Saltwater crocodiles (Crocodylus porosus) are potentially dangerous to humans, yet they have majo... more Saltwater crocodiles (Crocodylus porosus) are potentially dangerous to humans, yet they have major cultural value to many people in Timor-Leste. Recent increases in attack risk are influencing traditional attitudes, threatening culls of remaining wild crocodile populations. To understand patterns that may assist mitigation, we compiled attack records for the period of April 2007 to April 2014, using the CrocBITE online database. Recorded attacks (n=45) showed a high fatality rate (82.2%), the majority (77.8%) being recorded since 2010. The highest proportion of attacks (46.7%) occurred in southern coastal wetlands suited to crocodiles, areas representing major sources of food, livelihoods and ecosystem services (i.e. fisheries, timber, coastal protection) for locals. Subsistence fishing posed the highest attack risk, particularly from September to February when food security is low. Attacks matched gender roles (most victims were males, the primary fishers) and demographic patterns ...
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ABSTRACT
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Thesis (Ph. D.)--University of Bristol, 1996.
Bookmarks Related papers MentionsView impact
Attacks on humans by crocodilians have been documented reasonably well in developed countries in ... more Attacks on humans by crocodilians have been documented reasonably well in developed countries in the last few decades. Conversely, attacks in developing countries are typically poorly documented despite those countries holding the highest frequencies of crocodilian attacks. Here we present the results of an analysis of 1237 crocodilian attacks resulting in 674 fatalities worldwide for the period of January 2008 through July 8th, 2013. Attacks were recorded from 15 crocodilian species and fatal attacks were recorded from 7 of those 15 crocodilian species. 494 attacks resulting in 285 fatalities were recorded for Crocodylus porosus (problem areas identified for the species include East Timor, Sumatra and East Kalimantan of Indonesia, Sarawak of Malaysia, Orissa of India, and coastal Sri Lanka), 428 attacks resulting in 309 fatalities for C. niloticus, 98 attacks resulting in 50 fatalities for C. palustris (mostly from India, particularly within Gujarat state), 69 attacks resulting in ...
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As the country with the highest number of recent attack reports and very little crocodile populat... more As the country with the highest number of recent attack reports and very little crocodile population data, Indonesia is a perfect example of how CrocBITE can be used as a tool to help inform crocodilian conservation and management. Indonesia is a large, heavily populated nation composed of 34 provinces over an archipelago of 17,508 islands. There are currently four recognized crocodilian species present within Indonesia- the saltwater crocodile, Crocodylus porosus, the Siamese crocodile, C. siamensis, the New Guinea freshwater crocodile, C. novaeguineae, and the Malayan/false gharial, Tomistoma schlegelii. During the January 1st, 2007 through June 6th, 2014 period we recorded 279 crocodilian attacks resulting in 139 deaths in 27 of the 34 provinces. Attack reports were acquired almost entirely from online news reports, the vast majority of which were reported solely in the Indonesian language. The majority of attacks and deaths were attributed to C. porosus (268 attacks resulting in...
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Attacks on humans by crocodilians have been documented reasonably well in developed countries in ... more Attacks on humans by crocodilians have been documented reasonably well in developed countries in the last few decades. Conversely, attacks in developing countries are typically poorly documented despite those countries holding the highest frequencies of crocodilian attacks. Here we present the results of an analysis of over 600 crocodilian attacks worldwide for the period of 2008 through 2011. Attack data were compiled from a number of sources including online media reports, local wildlife officials, crocodilian experts, and relevant recent publications.
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ECOS, 2014
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Herpetology Notes, Jan 25, 2014
Although arboreality in extinct crocodilians is frequently suggested, the climbing abilities of e... more Although arboreality in extinct crocodilians is frequently suggested, the climbing abilities of extant crocodilians have never been discussed in any detail in scientific literature. We present an overview of published and anecdotal information on climbing in extant crocodilians, as well as original observations on four species representing two crocodile genera. These data suggest that climbing behaviour is common among crocodilians and might have multiple functions. The fact that at least some extant crocodilians are capable of climbing arboreal vegetation despite lacking any obvious morphological adaptations
for arboreality must be taken into account by paleontologists trying to elucidate behavioural clues from the morphology of
fossil taxa.
Bookmarks Related papers MentionsView impact
Wildlife Research, 2013
Context.Spread of the invasive cane toad (Rhinella marina) across northern Australia is of concer... more Context.Spread of the invasive cane toad (Rhinella marina) across northern Australia is of concern. Predator species, including the freshwater crocodile (Crocodylus johnstoni), are susceptible to cane toad toxins when ingested. Upstream populations of freshwater crocodiles are smaller than downstream counterparts because of limited resources. We measured the impact of cane toad arrival on densities of these upstream populations.
Aims.Our aim was to determine whether the influx of cane toads had a negative impact on populations of upstream
‘stunted’freshwater crocodiles.
Methods.Population surveys for crocodiles were conducted in three upstream creek systems, using day- and night-based
survey methods, before the arrival of cane toads in the area. These surveys were repeated under similar conditions following the arrival of cane toads, to compare the distribution and densities of freshwater crocodiles and, hence,measure the impact of cane toads.
Key results. There were significant declines in crocodile density at two survey sites following the arrival of cane toads, and
we found dead crocodiles and cane toad carcasses with crocodile bite marks. The third site showed no change in density. There was a decline in mean density across all sites from 3.0 crocodiles km–1 to 1.1 crocodiles km–1 following the arrival of cane toads.
Conclusions. There was an overall decrease in crocodile densities and a reduction in distribution following the arrival of
cane toads into the survey area. Dead crocodiles and evidence of their having eaten cane toads strongly suggest that these declines were caused directly by the arrival of cane toads into the area. One site showed no apparent change other than an increase in wariness, which may reflect the distribution of available feeding and shelter resources among the three sites.
Implications.These results suggest that upstream freshwater crocodile populations are highly susceptible to cane toad
toxins, and that impacts on their population can include local extirpation. Considering their morphological and possibly
genetic distinctiveness, the loss of these unique populations is of conservation concern.
Bookmarks Related papers MentionsView impact
Journal of Zoology, 1997
Flight performance and echolocation behaviour of the pond bat, Myotis dasycneme (Boie, 1825), wer... more Flight performance and echolocation behaviour of the pond bat, Myotis dasycneme (Boie, 1825), were investigated over canals and a lake in the Netherlands. Multi-flash stereophotogrammetry, linked with synchronous recording of echolocation calls, was used to reconstruct the three-dimensional flight paths of bats and to correlate flight behaviour with changes in pulse emission during echolocation. Echolocation calls during commuting flight at the canal were sigmoidal in structure, with an initial steep frequency modulated (FM) sweep followed by a more shallow sweep, ending with a second, rapid FM sweep. Similar calls were produced during the search phase of foraging, though longer duration quasi-CF (constant-frequency) calls, with longer interpulse intervals and much reduced initial and final FM sweeps, were produced by bats hunting over a large lake. Overall, calls were generally lower in frequency, with significantly longer pulse durations and interpulse intervals, compared with those of smaller trawling Myotis bats. Flight speeds were compared with predicted optima from aerodynamic models. Commuting bats exceeded predicted maximum range speed, which was considerably higher than that noted for other smaller species of trawling Myotis. Flight speed was significantly higher closer to the roost, at a narrower canal site. A negative correlation between wingbeat frequency and flight speed, and a facultative 1: 1 link between pulse emission and wingbeat during search phase were established. During commuting, the bats flew at a height above that which would normally confer substantial power savings through ground effect. It is argued that, by flying at a lower height, bats would compromise commuting speed. Echolocation calls produced during attempted prey capture were remarkably similar in design to those produced by those other Myotis species that forage in a similar fashion. Prey was detected at 2 m, and reaction distance was 1.8 m. Evidence of a physiological limit on pulse duration and interpulse interval during prey capture is presented. Overlap of emitted pulse and received echo may degrade the performance of echolocation in many bats, and overlap is generally avoided in M. dasycneme except perhaps when the bat is very close to the prey item.
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The Australasian Bat Society Newsletter, Apr 2012
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Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2006
We employed a spectroscopic assay, based on the hemolysis of sheep red blood cells (SRBCs), to as... more We employed a spectroscopic assay, based on the hemolysis of sheep red blood cells (SRBCs), to assess the innate immune function of saltwater and freshwater crocodiles in vitro. Incubation of serum from freshwater and saltwater crocodiles with SRBCs resulted in concentration-dependent increases in SRBC hemolysis. The hemolytic activity occurred rapidly, with detectable activity within 2 min and maximum activity at 20 min. These activities, in both crocodilian species, were heat sensitive, unaffected by 20 mM methylamine, and completely inhibited by low concentrations of EDTA, suggesting that the alternative serum complement cascade is responsible for the observed effects. The hemolytic activities of the sera were inhibited by other chelators of divalent metal ions, such as phosphate and citrate. The inhibition of SRBC hemolysis by EDTA could be completely restored by the addition of 10 mM Ca2+ or Mg2+, but not Ba2+, Cu2+ or Fe2+, indicating specificity for these metal ions. The serum complement activities of both crocodilians were temperature-dependent, with peak activities occurring at 25–30 °C and reduced activities below 25 °C and above 35 °C.
Bookmarks Related papers MentionsView impact
Journal of The Acoustical Society of America, 2010
ABSTRACT Sound production in reptiles is generally limited in scope, yet crocodilians have develo... more ABSTRACT Sound production in reptiles is generally limited in scope, yet crocodilians have developed a modest repertoire of vocal and non-vocal acoustic signals to convey a range of different information. This ability is perhaps less surprising considering that their Archosaur heritage is shared with dinosaurs and birds, and basic similarities to avian bioacoustics are apparent. An overview is presented of sound production and reception in crocodilians, the sound characteristics and repertoire of known signals, and the important role that these signals play in crocodilian behavior. The evolution of bioacoustics in this group is touched upon, based on biological and behavioral evidence between species.
Bookmarks Related papers MentionsView impact
Journal of Vertebrate Paleontology, 2005
... schlegelii S. Volia athollandersoni Crocodylus niloticus -7 Crocodylus acutus - Crocodylus po... more ... schlegelii S. Volia athollandersoni Crocodylus niloticus -7 Crocodylus acutus - Crocodylus porosus Crocodylus johnstoni Crocodylus mindorensis Crocodylus novaeguineae Crocodylus siamensis Deinosuchus sp. Baryphracta ...
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Wilderness & Environmental Medicine, 2005
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