The Good, the Bad, and the Ugly: Agonistic Behaviour in Juvenile Crocodilians

Brien, Matthew L.; Lang, Jeffrey W.; Webb, Grahame J. W.; Stevenson, Colin; Christian, Keith A.

doi:10.1371/journal.pone.0080872

Cited by 32 publications

(33 citation statements)

References 51 publications

(76 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More aggressive species such as saltwater crocodiles ( Crocodylus porosus ) and Nile crocodiles ( C . niloticus ) [ 23 ] are responsible for a much higher mortality of humans in unprovoked attacks. Between January 2008 and October 2013, 528 attacks by C .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dead or Alive? Factors Affecting the Survival of Victims during Attacks by Saltwater Crocodiles (Crocodylus porosus) in Australia

Fukuda¹,

Manolis²,

Saalfeld³

et al. 2015

PLoS ONE

View full text Add to dashboard Cite

Conflicts between humans and crocodilians are a widespread conservation challenge and the number of crocodile attacks is increasing worldwide. We identified the factors that most effectively decide whether a victim is injured or killed in a crocodile attack by fitting generalized linear models to a 42-year dataset of 87 attacks (27 fatal and 60 non-fatal) by saltwater crocodiles (Crocodylus porosus) in Australia. The models showed that the most influential factors were the difference in body mass between crocodile and victim, and the position of victim in relation to the water at the time of an attack. In-water position (for diving, swimming, and wading) had a higher risk than on-water (boating) or on-land (fishing, and hunting near the water's edge) positions. In the in-water position a 75 kg person would have a relatively high probability of survival (0.81) if attacked by a 300 cm crocodile, but the probability becomes much lower (0.17) with a 400 cm crocodile. If attacked by a crocodile larger than 450 cm, the survival probability would be extremely low (<0.05) regardless of the victim’s size. These results indicate that the main cause of death during a crocodile attack is drowning and larger crocodiles can drag a victim more easily into deeper water. A higher risk associated with a larger crocodile in relation to victim’s size is highlighted by children’s vulnerability to fatal attacks. Since the first recently recorded fatal attack involving a child in 2006, six out of nine fatal attacks (66.7%) involved children, and the average body size of crocodiles responsible for these fatal attacks was considerably smaller (384 cm, 223 kg) than that of crocodiles that killed adults (450 cm, 324 kg) during the same period (2006–2014). These results suggest that culling programs targeting larger crocodiles may not be an effective management option to improve safety for children.

show abstract

Section: Introductionmentioning

confidence: 99%

“…Here we examine a 42-year dataset of attacks by C . porosus , the largest [ 27 ], most aggressive [ 23 ] extant crocodilian species in northern Australia where one of the largest C . porosus populations in the world exists [ 28 ].…”

Section: Introductionmentioning

confidence: 99%

Dead or Alive? Factors Affecting the Survival of Victims during Attacks by Saltwater Crocodiles (Crocodylus porosus) in Australia

Fukuda¹,

Manolis²,

Saalfeld³

et al. 2015

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…Despite the presence of sperm in every egg, there were differences in developmental rates. Differences in developmental rates may be a result of social grouping as crocodilians are behaviorally complex (Augustine, Pryes, & Evans, ; Augustine & Watkins, ; Brien, Lang, Webb, Stevenson, & Christian, ; Brien, Webb, Lang, McGuinness, & Christian, , ; Garrick & Lang, ; Garrick, Lang, & Herzog, ; Lang, ; Thorbjarnarson & Hernández, ; Vliet , , ). In captive crocodilian groups, competition for resources leads to the establishment of dominance hierarchies instead of established territories (Brien et al, ) and increased competition leads to agonistic behaviors (Drummond, ; Lovern & Jenssen, ).…”

Section: Discussionmentioning

confidence: 99%

Crocodilian perivitelline membrane‐bound sperm detection

Augustine

2017

Zoo Biology

View full text Add to dashboard Cite

Advanced reproductive technologies (ART's) are often employed with various taxa to enhance captive breeding programs and maintain genetic diversity. Perivitelline membrane-bound (PVM-bound) sperm detection has previously been demonstrated in avian and chelonian species as a useful technique for breeding management. In the absence of embryotic development within an egg, this technique can detect the presence of sperm trapped on the oocyte membrane confirming breeding, male reproductive status, and pair compatibility. PVM-bound sperm were successfully detected in three clutches of Cuban crocodile (Crocodylus rhombifer) eggs at the Smithsonian's National Zoological Park (NZP) for the first time in any crocodilian species. PVM-bound sperm were detected in fresh and incubated C. rhombifer eggs, as well as eggs that were developing (banded) and those that were not (not banded). The results of this study showed significant differences in average sperm densities per egg between clutches (p = 0.001). Additionally, there was not a significant difference within clutches between eggs that banded and those that did not band (Clutch A, p = 0.505; Clutch B, p = 0.665; Clutch C, p = 0.266). The results of this study demonstrate the necessity to microscopically examine eggs that do not develop (do not band), to determine if sperm is present, which can help animal managers problem solve reproductive shortcomings. PVM-bound sperm detection could be a useful technique in assessing crocodilian breeding programs, as well as have potential uses in studies assessing sperm storage, artificial insemination, and artificial incubation.

show abstract

“…Adult crocodilians primarily use vocalizations in courtship, to assert dominance, or to communicate with their young (2), although, several species of crocodilians begin emitting vocalizations in the hours before they hatch (1). This lifecycle stage is known as the late embryonic stage.…”

mentioning

confidence: 99%

“…Vocalizations are arguably most important to crocodilian survival in the late embryonic stage and the juvenile stage (2). Crocodilians are most vulnerable to predation as eggs and newly hatched juveniles, while larger crocodilians have a higher survival rate (4).…”

mentioning

confidence: 99%