dslramsey / tahr_abundance

Code for calculating tahr abundance from helicopter counts from the paper Ramsey et al (2022) JWM

Using Helicopter Counts to Estimate the Abundance of Himalayan Tahr in New Zealand’s Southern Alps

Overview

This repository contains data and code from:

Ramsey, D.S.L., Forsyth, D.M., Perry, M., Thomas, P., McKay, M., and Wright, E. (2022). “Using Helicopter Counts to Estimate the Abundance of Himalayan Tahr in New Zealand’s Southern Alps” Journal of Wildlife Management

File descriptions:

• r/tahr_models.r reads data and fits dynamic N-mixture models to helicopter counts from 117 plots using nimble.
• r/misc_functions.r contains various functions require by the main script.
• data/tahr_data.rds helicopter count data for 117 plots by 3 occasions including metadata.
• data/plots.rds sf object of plot boundaries.
• data/MU.rds sf object of tahr management unit boundaries.
• data/PCL.rds sf object of public conservaton land boundaries.
• data/nzsouth.rds sf object of the south island of New Zealand.

Prerequisites

The script require packages tidyverse, nimble, sf, nngeo, MCMCviz, bayesplot, gridExtra,progress,ggspatial and ggvoronoi.