L'écoute des crapauds révèle des secrets d'expansion

Researchers analyzing over 3 million toad calls from across Australia have uncovered critical insights into the breeding habits of invasive cane toads, offering potential strategies to slow their spread. The findings, published in the journal NeoBiota, reveal that toads prefer specific environmental conditions for calling, low moonlight, low wind, high humidity, and minimal vegetation obstruction. However, the most significant factor influencing toad vocalization was the presence of calls from the previous night, which encouraged more frequent and intense mating calls. The study, led by James Cook University ecologist Franco Leung, examined data collected from 405,588 hours of nighttime audio recordings taken at 40 different Australian Acoustic Observatory (A2O) sites spanning Queensland, the Northern Territory, and Western Australia. These recordings captured the nocturnal soundscape, allowing researchers to track patterns in toad calling behavior. By integrating climate data such as wind speed, humidity levels, and cloud cover with ecological factors like vegetation density and proximity to water sources, the team created a comprehensive model of toad activity. Toads begin calling at sunset, reaching peak activity around midnight, and gradually reduce their vocalizations before sunrise. This pattern suggests that toads adjust their behavior based on both environmental cues and social interactions. Leung noted that the ability of toads to breed continuously throughout the year contributes significantly to their invasive success. Their capacity to thrive in diverse climates, coupled with toxic secretions that deter predators, has allowed them to expand rapidly across Australia. Originally introduced to Queensland in the mid-20th century to control sugar cane beetle populations, cane toads have since spread far beyond their intended range. Today, they are found in multiple states, extending from New South Wales in the south to Cape York in the north and the Kimberley region in the west. Scientists warn that the toads are continuing their march further southward, posing a growing threat to local ecosystems and biodiversity. The research provides valuable tools for managing the toad population. By identifying optimal times and locations for toad activity, conservationists can better target efforts to capture and control invasive populations. Leung emphasized that understanding when and where toads are most active could improve the effectiveness of eradication programs, particularly in newly invaded areas where early intervention is crucial. The study’s methodology highlights the power of acoustic monitoring in tracking wildlife behavior. Continuous audio recordings from remote observatories offer a non-intrusive means of studying animal activity, especially for species that are difficult to observe directly. The integration of environmental data with sound analysis allows for a deeper understanding of how external factors influence biological behaviors. As the toads continue their expansion, the need for innovative management strategies becomes increasingly urgent. The findings underscore the importance of long-term ecological monitoring and the application of advanced technologies in addressing invasive species challenges. With continued research and collaboration among scientists, there is hope that the spread of cane toads can be mitigated, preserving native habitats and reducing ecological disruption.