1. Passive acoustic monitoring (PAM) has emerged as a transformative tool for applied ecology, conservation and biodiversity monitoring, but its potential contribution to fundamental ecology is less often discussed, and fundamental PAM studies tend to be descriptive, rather than mechanistic.2. Here, we chart the most promising directions for ecologists wishing to use the suite of currently available acoustic methods to address long-standing fundamental questions in ecology and explore new avenues of research. In both terrestrial and aquatic habitats, PAM provides an opportunity to ask questions across multiple spatial scales and at fine temporal resolution, and to capture phenomena or species that are difficult to observe. In combination with traditional approaches to data collection, PAM could release ecologists from myriad limitations that have, at times, precluded mechanistic understanding.3. We discuss several case studies to demonstrate the potential contribution of PAM to biodiversity estimation, population trend analysis, assessing climate change impacts on phenology and distribution, and understanding disturbance and recovery dynamics. We also highlight what is on the horizon for PAM, in terms of near-future technological and methodological developments that have the potential to provide advances in coming years.4. Overall, we illustrate how ecologists can harness the power of PAM to address fundamental ecological questions in an era of ecology no longer characterised by data limitation.Recent developments in data acquisition, storage and processing have led to Passive acoustic monitoring (PAM; Box 1) approaches being increasingly adopted for a wide array of ecological applications and conservation management (
The Collared Kingfisher species complex is the most widespread of the ‘great speciator’ lineages of the Indo‐Pacific. They have shown a remarkable ability to spread and diversify. As a result of this rapid diversification, Todiramphus species are often found in secondary sympatry. In Southeast Sulawesi, Indonesia, two Todiramphus species are present, the breeding resident Collared Kingfisher Todiramphus chloris and the overwintering migratory Sacred Kingfisher Todiramphus sanctus. We investigated the effect of isolation on these closely related species by comparing their populations on mainland Sulawesi and its larger continental islands, with populations on the small, oceanic Wakatobi Islands. Within our wider analysis we provide further support for the distinctiveness of the Sulawesi Collared Kingfisher population, perhaps isolated by the deep water barrier of Wallace's line. Within Sulawesi we found that populations of Collared Kingfisher on the Wakatobi Islands had diverged from those on mainland Sulawesi, differing both in morphology and in mitochondrial DNA. In contrast, there was no divergence between Sacred Kingfisher populations in either morphology or mitochondrial DNA. We propose that a difference in habitat occupied by Collared Kingfisher populations between the mainland and continental islands vs. oceanic islands has caused this divergence. Mainland Collared Kingfishers are predominately found inland, whereas Wakatobi Collared Kingfishers are also found in coastal habitats. The larger body size of Wakatobi Collared Kingfisher populations may be a result of increased competition with predominantly coastal Sacred Kingfisher populations. The uniform nature of Sacred Kingfisher populations in this region probably reflects their consistent habitat choice (coastal mangrove) and their migratory nature. The demands of their breeding range are likely to have an even stronger selective influence than their Sulawesi wintering range, limiting their scope for divergence. These results provide insight into the adaptability of the widespread Todiramphus lineage and are evidence of the need for further taxonomic revision of Collared Kingfisher populations.
Mangroves are uniquely important ecosystems, for preserving biodiversity, sustaining livelihoods, and mitigating against climate change. However, they are degraded globally and are therefore a priority for ecosystem restoration. To date, the assessment of mangrove restoration outcomes is generally poor, and the limited studies that do exist are focused largely on forest area. Thus, more holistic ways of assessing the outcomes of mangrove restoration projects on biodiversity and associated ecological processes are urgently needed. Ecological networks are a useful tool for simultaneously examining both. Here, we assessed the utility of using species‐interaction networks for evaluating mangrove restoration outcomes for the first time. We compared the structure and complexity of mangrove ecological networks in replicated “monoculture reforestation,” “mixed species regeneration” and “reference forest” plots in two study areas in Sulawesi, Indonesia, an estuarine, and a coastal fringe mangrove system. We also combined and evaluated sampling methods, utilizing traditional plant–animal sampling while also integrating video recording data in a novel way. We found significant differences in the structure and complexity of mangrove networks between restored and natural plots, with contrasting effects between the two sites. Our results show differences in the complex ways in which taxa interact in mangrove restoration projects, which would be overlooked if common biodiversity metrics, such as species richness, were used alone, with consequences for the restoration of ecosystem functioning. We also highlight the utility of video recording data collection for constructing species‐interaction networks, overcoming the detrimental impacts of observer presence for some key species.
We highlight hitherto unreported populations of two globally threatened phalangerid species on south-east Sulawesi’s offshore islands – bear cuscus (Ailurops ursinus) and small Sulawesi cuscus (Strigocuscus celebensis) – and observations of a third range-restricted species – Peleng cuscus (Strigocuscus pelengensis). Our data are based on records made during 11 years of seasonal surveys on Buton, and short-term expeditions to Kabaena and Manui. Our observations of S. celebensis on Buton, where it occurs in three protected areas, represent an important range extension for this species, as do our observations of A. ursinus on Kabaena, where it is also widespread. We also report the unexpected presence of S. pelengensis on Manui. Buton, in particular, appears to be an important stronghold for both A. ursinus and S. celebensis, given that forest ecosystems here remain extensive and relatively intact. Both these species may also display a previously unreported adaptability to disturbed forest and even some non-forest habitats within our study area. Hunting pressures, a proven threat to these species in northern Sulawesi, may also be lesser here.
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