Importance of getting the numbers right: quantifying the rapid and substantial decline of an abundant marsupial, Bettongia penicillata
Bibliographic record
Abstract
Context A reliable measure of population size is fundamental to ecology and conservation but is often difficult to obtain. The woylie, Bettongia penicillata, provides an example where ‘getting the numbers right’ has important implications in verifying and quantifying the recent unexpected, rapid and substantial declines across much of its range. Initial estimates prompted a conservation-status upgrade for the species to Endangered by the Australian Government. The present paper constitutes the foundational paper addressing the first steps of a decline diagnosis framework intended to identify the causes of the recent declines. Aims To verify whether the declines in woylie trap-capture rates are representative of population change; better quantify the size of the largest woylie populations; and review what is understood about the ecology of the woylie and identify key knowledge gaps that may be relevant to identifying the causes of the recent declines. Methods Monitoring data from live-cage trapping (transects and grids), sandpads, woylie diggings and nest-density surveys and spotlighting were collated. Population measures derived from trapping data included capture rates, number of individuals, abundance estimates based on capture–mark–recapture modelling and density using spatially explicit capture–recapture models (SECR). Key results The declines in woylie trap-capture rates were verified as real population declines and corresponded closely with other measures of abundance derived from the same trapping data as well as with independent measures. A 95% decline occurred in the largest extant woylie populations (in the Upper Warren region, Western Australia) between 2002 and 2008. At a species level, woylies declined ~90% (1999–2006), from a peak of ~200 000 individuals in 1999. Conclusions An accurate formal conservation status is an important factor in promoting the conservation of a species. It is recommended that the woylie be considered for Critically Endangered status under the Australian EPBC Act. Implications Adequate and effective monitoring of species is critical to detecting and quantifying population changes in a timely manner. Having an accurate measure of population size can have a significant impact on the effectiveness of conservation and management efforts.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".