Using experimental reintroductions to resolve the roles of habitat quality and metapopulation dynamics on patch occupancy in fragmented landscapes

Despite mounting evidence on the ecological impacts of damming for biodiversity, little is known regarding its consequences in the hyper-diverse Southeast Asian tropical forests. Here we assess the effects of habitat loss and fragmentation on the diversity and activity of insectivorous bats within the hydroelectric Kenyir Lake in peninsular Malaysia. We surveyed bat assemblages on 26 islands and two mainland continuous forest sites using passive acoustic monitoring. Echolocation calls were classified into sonotypes, each corresponding to either one or multiple species, and grouped into foraging guilds. We then examined bat overall assemblage (sonotype richness, activity, and composition), guild- and sonotype-specific activity. From 9360 hours of recordings, we identified 16 bat sonotypes, including 10 forest (2854 bat passes), three edge (13 703) and three open-space foragers (3651). Sonotype richness increased towards denser forest structures (higher Normalized Difference Vegetation Index - NDVI), while species composition varied across the gradient of forest area. Forest foragers were positively affected by NDVI and negatively affected by distance to the closest neighbour, whereas edge foragers' activity increased in smaller islands. Of the six sonotypes analysed, the activity of one forest sonotype increased with forest area, while that of one edge sonotype decreased. Ensuring habitat quality within insular forest remnants, in addition to their functional connectivity, maximises bat diversity, including the persistence of forest foraging species. Future hydropower development should therefore avoid the creation of a myriad of small, isolated, and habitat-degraded islands further characterised by altered levels of bat diversity and guild-level activity.

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Section: Discussionsupporting

confidence: 76%

“…(Struebig et al, 2013). Our findings reiterate the importance of habitat quality as a key driver of species diversity in fragmented landscapes (Armstrong et al, 2022;Poniatowski et al, 2018). Furthermore, bat assemblage composition varied along the gradient of forest area, with edge foragers being particularly active on smaller islands.…”

Section: Discussionsupporting

confidence: 59%

Foraging guild modulates insectivorous bat responses to habitat loss and insular fragmentation in peninsular Malaysia

Hazard

Froidevaux

Yoh

et al. 2023

Preprint

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“…Before embarking on a main programme, scientifically robust trials or experimental releases can help remove potentially flawed prior assumptions of founder ecology, a factor which has frequently hampered the effectiveness of translocations historically [ 2 ]. Whether a trial, or simply the first year of longer planned releases, comprehensive monitoring at this stage is critical for understanding founders’ initial physical and behavioural response to the overall release process and thus informative to the expected progression (or not) and strategy for the main stages of a translocation [ 16 ].…”

Section: Discussionmentioning

confidence: 99%

What has biotelemetry ever done for avian translocations?

Hodgson

Bearhop

2022

Mov Ecol

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Species translocation is a popular approach in contemporary ecological restoration and rewilding. Improving the efficacy of conservation translocation programmes requires a combination of robust data from comparable populations, population viability modelling and post-release monitoring. Biotelemetry is becoming an ever more accessible means to collect some of the high-resolution information on the ecology and behaviour of founding populations that such evaluations require. Here, we review 81 published case studies to consider how this capability could increase the success of avian translocations. We found that 67 translocations favoured traditional radio telemetry, with surveillance focussing mostly on immediate post-release dispersal, survival and breeding attempts. Just 28 projects tracked founder individuals for longer than 1 year and no studies referenced pre-release sampling or planning using biotelemetry. While our review shows that tracking devices have been deployed extensively in translocation projects, its application has been mostly limited to short-term spatial and demographic monitoring. We conclude that biotelemetry is a powerful tool for harnessing a multitude of lifetime eco-behavioural data which can be used to build valuable predictive models and surveillance programmes, but this capability has yet to be fully realised by researchers in avian translocations.

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“…A key area of contention concerns the importance of different kinds of patch characteristics to turnover and whether their influence shifts under nonequilibrium conditions. Metapopulation theory, which was originally based on biogeographic relationships of patch area and isolation (Hanski, 1999 ), has been challenged by the roles of patch habitat quality (Armstrong, 2005 ; Armstrong et al, 2022 ; Ovaskainen & Saastamoinen, 2018 ; Schooley & Branch, 2009 ) and the surrounding matrix (Gebauer et al, 2013 ; Matthews, 2021 ; Ricketts, 2001 ). In addition, an important criticism of metapopulation theory in general, and the incidence function model in particular (Hanski, 1994 ; Risk et al, 2011 ; Thomas & Hanski, 2004 ), is that they assume equilibrium conditions or “quasi‐stationarity,” with little change in patch number, size or quality (Baguette, 2004 ; Holyoak & Ray, 1999 ).…”

Section: Introductionmentioning

confidence: 99%

Stability of patch‐turnover relationships under equilibrium and nonequilibrium metapopulation dynamics driven by biogeography

et al. 2022

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Two controversial tenets of metapopulation biology are whether patch quality and the surrounding matrix are more important to turnover (colonisation and extinction) than biogeography (patch area and isolation) and whether factors governing turnover during equilibrium also dominate nonequilibrium dynamics.We tested both tenets using 18 years of surveys for two secretive wetland birds, black and Virginia rails, during (1) a period of equilibrium with stable occupancy and(2) after drought and arrival of West Nile Virus (WNV), which resulted in WNV infections in rails, increased extinction and decreased colonisation probabilities modified by WNV, nonequilibrium dynamics for both species and occupancy decline for black rails. Area (primarily) and isolation (secondarily) drove turnover during both stable and unstable metapopulation dynamics, greatly exceeding the effects of patch quality and matrix conditions. Moreover, slopes between turnover and patch characteristics changed little between equilibrium and nonequilibrium, confirming the overriding influences of biogeographic factors on turnover.

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Using experimental reintroductions to resolve the roles of habitat quality and metapopulation dynamics on patch occupancy in fragmented landscapes

Abstract: Experimental reintroductions are essential for testing rapid inferences about effects of isolation and habitat quality on patch occupancy.

Cited by 6 publications

References 43 publications

Foraging guild modulates insectivorous bat responses to habitat loss and insular fragmentation in peninsular Malaysia

Foraging guild modulates insectivorous bat responses to habitat loss and insular fragmentation in peninsular Malaysia

What has biotelemetry ever done for avian translocations?

Stability of patch‐turnover relationships under equilibrium and nonequilibrium metapopulation dynamics driven by biogeography

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