Coyote Inventory - Fladry Analysis - Analysis Scripts for Cape Hatteras and Cape Lookout National Seashores and Pea Island National Wildlife Refuge
Sossover D. 2026. Coyote Inventory - Fladry Analysis - Analysis Scripts for Cape Hatteras and Cape Lookout National Seashores and Pea Island National Wildlife Refuge. National Park Service
R script and associated data for the fladry avoidance analysis, testing fladry as a non-lethal deterrent. We used the South Core Banks north/south partition shapefile to assign each GPS fix to either the north or south of the island prior to this Rscript using ArcGIS Pro. Fladry is a traditional livestock protection tool consisting of flagging hung along a rope perimeter. We tested it as a non-lethal coyote deterrent by setting up a fladry line across the width of South Core Banks during the deployment period June 17 – August 16, 2024. Three collared residents on South Core Banks (Ed, Martha, Rahzar) provided the GPS tracking data for this analysis. GPS fixes for each individual were pre-processed in ArcGIS Pro: the South Core Banks island boundary shapefile was split into north and south zones along the fladry line, and each fix was spatially assigned to either the north or south side. The R script Fladry_Analysis.R then: • Assigns each fix a period label (pre, during, or post deployment) relative to the deployment window. • Computes weekly observation effort per individual (inter-fix hours, capped at 0.5 h to limit gaps) and detects southward-to-northward (S→N) crossings of the fladry line. • Calculates crossing rates per 24 animal-hours by period, both pooled across individuals and per individual. • Applies a robust crossing criterion requiring ≥30 minutes of consecutive north-side residence before a S→N transition is counted, reducing false positives from brief incursions. • Performs Poisson rate tests comparing crossing rates during vs. pre and during vs. post deployment to assess whether fladry significantly reduced northward movement.
- Type
- Script
- Authors
- Sossover, Daniel
- Date of Issue
- 2026-03-11
- Publisher
- National Park Service
- Units
- CAHA , CALO
- Keywords
- CAHA, CALO, coyote, fladry, IMD, inter island movement, Inventory and Assessment Program, Islands, Movement, National Park Service, NPS, NPS Inventory and Monitoring Division, Pea Island National Wildlife Refuge, Population Dynamics, population modeling, Species Inventory
See also
- Coyote Inventory - South Core Banks Fladry Avoidance - Geospatial Dataset for Cape Hatteras and Cape Lookout National Seashores and Pea Island National Wildlife Refuge
- Coyote Inventory - Additional Deliverables Overview - for Cape Hatteras and Cape Lookout National Seashores and Pea Island National Wildlife Refuge