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Simulations inform design of regional occupancy-based monitoring for a sparsely distributed, territorial species.

ABSTRACT: Sparsely distributed species attract conservation concern, but insufficient information on population trends challenges conservation and funding prioritization. Occupancy-based monitoring is attractive for these species, but appropriate sampling design and inference depend on particulars of the study system. We employed spatially explicit simulations to identify minimum levels of sampling effort for a regional occupancy monitoring study design, using white-headed woodpeckers (Picoides albolvartus), a sparsely distributed, territorial species threatened by habitat decline and degradation, as a case study. We compared the original design with commonly proposed alternatives with varying targets of inference (i.e., species range, space use, or abundance) and spatial extent of sampling. Sampling effort needed to achieve adequate power to observe a long-term population trend (?80% chance to observe a 2% yearly decline over 20 years) with the previously used study design consisted of annually monitoring ?120 transects using a single-survey approach or ?90 transects surveyed twice per year using a repeat-survey approach. Designs that shifted inference toward finer-resolution trends in abundance and extended the spatial extent of sampling by shortening transects, employing a single-survey approach to monitoring, and incorporating a panel design (33% of units surveyed per year) improved power and reduced error in estimating abundance trends. In contrast, efforts to monitor coarse-scale trends in species range or space use with repeat surveys provided extremely limited statistical power. Synthesis and applications. Sampling resolutions that approximate home range size, spatially extensive sampling, and designs that target inference of abundance trends rather than range dynamics are probably best suited and most feasible for broad-scale occupancy-based monitoring of sparsely distributed territorial animal species.

SUBMITTER: Latif QS

PROVIDER: S-EPMC5773320 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Simulations inform design of regional occupancy-based monitoring for a sparsely distributed, territorial species.

Latif Quresh S QS Ellis Martha M MM Saab Victoria A VA Mellen-McLean Kim K

Ecology and evolution 20171220 2

Sparsely distributed species attract conservation concern, but insufficient information on population trends challenges conservation and funding prioritization. Occupancy-based monitoring is attractive for these species, but appropriate sampling design and inference depend on particulars of the study system. We employed spatially explicit simulations to identify minimum levels of sampling effort for a regional occupancy monitoring study design, using white-headed woodpeckers (<i>Picoides albolva ...[more]

PMID: 29375788

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Project description:The use of robust ecological data to make evidence-based management decisions is frequently prevented by limited data quantity or quality, and local ecological knowledge (LEK) is increasingly seen as an important source of information for conservation. However, there has been little assessment of LEK's usefulness for informing prioritization and management of landscapes for threatened species, or assessing comparative species status across landscapes.A large-scale interview survey in the Annamite Mountains (Vietnam and Lao PDR) compiled the first systematic LEK data set for saola Pseudoryx nghetinhensis, one of the world's rarest mammals, and eight other ungulates. Saola conservation is hindered by uncertainty over continued presence across much of its proposed distribution. We analysed comparative LEK-based last-sighting data across three landscapes to determine whether regional sighting histories support previous suggestions of landscape importance for saola conservation (Hue-Quang Nam: top-priority Vietnamese landscape; Pu Mat: lower priority Vietnamese landscape; Viengthong: high-priority Lao landscape) and whether they constitute an effective spatial prioritization tool for cryptic species management.Wild pig and red muntjac may be the only Annamite ungulates with stable populations; the regional status of all other species appears to be worse. Saola have declined more severely and/or are significantly rarer than most other ungulates and have been seen by relatively few respondents. Saola were also frequently considered locally rarest or declining, and never as species that had not declined.In contrast to other species, there are no regional differences in saola sighting histories, with continued persistence in all landscapes challenging suggestions that regional status differs greatly. Remnant populations persist in Vietnam despite heavy hunting, but even remote landscapes in Lao may be under intense pressure.Synthesis and applications. Our local ecological knowledge data suggest that intact saola populations probably no longer exist, but individuals persist in all three landscapes, making management activities to reduce hunting pressure on ungulates in each landscape a conservation priority. Analysis of last-sighting histories can constitute an important conservation tool when robust data are otherwise unavailable, and collection of last-sighting records should be incorporated more widely into field studies and management of other highly threatened, cryptic species. Our local ecological knowledge data suggest that intact saola populations probably no longer exist, but individuals persist in all three landscapes, making management activities to reduce hunting pressure on ungulates in each landscape a conservation priority. Analysis of last-sighting histories can constitute an important conservation tool when robust data are otherwise unavailable, and collection of last-sighting records should be incorporated more widely into field studies and management of other highly threatened, cryptic species.

Dataset Information

Simulations inform design of regional occupancy-based monitoring for a sparsely distributed, territorial species.

Publications

Simulations inform design of regional occupancy-based monitoring for a sparsely distributed, territorial species.

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