Professor G\u00f3ngora said the genetic differences in the small Liverpool River crocodiles was no greater than that found between freshwater crocodiles (Crocodylus johnstoni) that lived in other river systems.<\/p>\n
“They are a unique population, but we did not find strong evidence that they are a separate species,” he said.<\/p>\n
While not a new species, Professor G\u00f3ngora said pygmy crocodiles represented an ecological form of freshwater crocodile adapted to isolated escarpments.<\/p>\n
He said this could warrant more protection for the Liverpool River crocodiles and a second population of small crocodiles in the Bullo River.<\/p>\n
“Those adaptations are valuable and worth conserving,” Professor G\u00f3ngora said.<\/p>\n
Why are they so small?<\/p>\n
The small size of pygmy crocodiles compared to other freshwater populations is thought to be an example of “phenotypic plasticity”, a phenomenon whereby a species develops different characteristics based on where it lives.<\/p>\n
“A simple example is that identical plants can grow tall and lush in good soil but remain small and stunted in poor soil,” Professor G\u00f3ngora said.<\/p>\n
“They are still the same species, but they respond differently to different conditions.”<\/p>\n
Centre for Crocodile Research managing director Sally Isberg, who was not involved with the study, said their small size came from adapting to smaller water pools on the escarpment, where less prey was available compared to down river.<\/p>\n
“They’ve been able to mature at a smaller size because obviously the end goal is to pass on your genes,” Dr Isberg said.Discerning crocs from logs the challenge for AI trial<\/a><\/p>\n Researchers are trialling artificial intelligence to detect crocodiles in north Queensland waterways, but its success depends on human training to ensure accuracy.<\/p>\n The original survey that described the Liverpool River’s pygmy crocodiles found them in the upper reaches of the river past natural barriers, like waterfalls, where there weren’t any large fish species.<\/p>\n The surveyors found the largest mature female pygmy crocodiles were between 1.07 metres and 1.12m long, and a male was 1.18m.<\/p>\n Elsewhere in the NT, female freshwater crocodiles mature at about 1.5m and grow up to 2m in length. While males mature at 1.6m to 2m and reach 2.5m.<\/p>\n Professor G\u00f3ngora said freshwater crocodiles were known to grow larger in habitats with more permanent water and more abundant food.<\/p>\n For example, in the catfish-filled Lake Argyle in Western Australia, freshwater crocodiles have been recorded reaching lengths of about 3m.<\/p>\n Freshwater crocodiles living in Lake Argyle have been found to reach about 3m in length. (iNaturalist: Alan Bell<\/a>\/Freshwater crocodile<\/a>\/CC BY 4.0<\/a>)<\/p>\n Do pygmy crocodiles need more conservation effort?<\/p>\n Dr Isberg said there was a point of alarm a few years ago for Bullo River pygmy crocodiles when cane toads, which can kill predators when ingested, moved through the region.<\/p>\n The exact state of the two pygmy crocodile populations is unclear, with no current population estimates.<\/p>\n Professor G\u00f3ngora said there were high levels of inbreeding in the Liverpool River population compared to other crocodiles in the genetic study.<\/p>\n “That is not surprising given how isolated these crocodiles are,” he said.<\/p>\n “Inbreeding can reduce genetic diversity, which may make populations less resilient to environmental change and other threats.”<\/p>\n Professor G\u00f3ngora said more research was needed to understand the extent of inbreeding and whether it was affecting their long-term health, survival and ability to adapt to future challenges.<\/p>\n He said future research directions included more genetic sampling of the Bullo River crocodiles, studies on movement patterns and connectivity of the two populations between river systems, and ecological research into food availability, habitat quality and how the pygmy crocs responded to environmental pressures.<\/p>\n “Together, that would help us better understand how isolation and evolutionary processes are shaping these crocodile populations,” Professor G\u00f3ngora said.<\/p>\n In the meantime, he said conservation agencies could identify pygmy crocodiles as “unique management units” and prioritise them for monitoring, threat mitigation and recovery actions.<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/09\/154cd374c22da7f576e6ec11d9637f01.jpeg\")
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