gilmour_fidelity: Gilmour's Fidelity Index
In abfleishman/trakR: Basic Animal Tracking Data Analysis Tools

gilmour_fidelity

R Documentation

Gilmour's Fidelity Index

Description

Used for calculation of Fidelity Index as described by: Gilmour, ME, JA Castillo-Guerrero, AB Fleishman, S Hernandez-Vazquez, HS Young, SA Shaffer. 2018. Plasticity of foraging behaviors in response to diverse environmental conditions. Ecosphere 9(7):e02301. https://doi.org/10.1002/ecs2.2301 (open access)

Usage

gilmour_fidelity(
  dat,
  Longitude,
  Latitude,
  animal_id,
  trip_id,
  distance2colony,
  bear2col
)

Arguments

`dat`	a data frame of tracking data with columns that include positions (longitude/Latitude, Easting/Northing,etc), an animal ID, unique trip IDs (unique to each animal/trip combo), a column with a distance to the colony, and a column with a bearing from each point to the colony.
`Longitude`	quoted column name for location in the x direction. can be longitude or easting or any other x coordinator
`Latitude`	quoted column name for location in the y direction. can be latitude or northing or any other y coordinator
`animal_id`	quoted column name of a unique ID field for each animal
`trip_id`	quoted column name of a unique ID field for each animal/trip (can be a combo of animalID and a trip number for that animal)
`distance2colony`	quoted column name of a distance to the colony (units do not matter)
`bear2col`	quoted column name of a bearing in degrees from each point to the colony

Details

This function compares maximum displacement (distance and angle) of two separate trips from a point of origin. Multiple displacement values can be compared. These displacement values are centered and scaled to create an index of site fidelity that ranges -1 to 1.

The equations used in this script are modified from: Willis-Norton et al. 2015. Deep-Sea Research Part II: Topical Studies in Oceanography 113:260-267 Hazen et al. 2016. Journal of Applied Ecology 54:1415-1428, and Shaffer et al. 2017. Movement Ecology 5:27 https://doi.org/10.1186/s40462-017-0118-9.

Value

a list of data.frames with the fidelity index for each trip combination (fidelity_index_trips ) and an average fidelity index for each animal (fidelity_index_animal)