# Introduction to distance sampling

David L Miller

### Overview

- Line transects
- Simple estimates of abundance
- Why is detectability important?
- What is a detection function?
- First look at fitting models in R

### How many animals are there? (500!)

### General strategy

- Take a sample in some fixed areas
- Find density/abundance in
*covered area*
- Multiply up to get abundance

### General strategy (What did we assume?)

- Take a sample in some fixed areas
- Find density/abundance in
*covered area*
- Multiply up to get abundance

### Plot sampling

- Surveyed 10 quadrats (each \( 0.1^2 \) units)
- Total covered area \( a=10 * 0.1^2 = \) 0.1

- Saw \( n= \) 59 animals
- Estimated density \( \hat{D}=n/a= \) 590
- Total area \( A=1 \)
- Estimated abundance \( \hat{N}=\hat{D}A= \) 590