Estimate Calf-Cow Ratio.
Usage
bbr_calf_cow_ratio(
x,
adult_female_proportion = 0.65,
sex_ratio = 0.5,
variance = "bootstrap",
year_start = 4L
)Format
The return object has these columns:
- PopulationName
Population name
- Year
Year sampled
- estimate
Calf-Cow ratio estimate
- lower
Confidence limit
- upper
Confidence limit
- groups
Groups sampled
- female_calves
Estimated female calves
- females
Estimated adult females
Arguments
- x
A data frame that has recruitment data.
- adult_female_proportion
Assumed or estimated proportion of females in the population used to assign unknown sex caribou. Values must be between 0 and 1. Can be set to 0 to exclude unknown sex caribou from recruitment estimates. The default is set at 0.65.
- sex_ratio
Sex ratio of caribou at birth used to assign calves and yearlings as male or female. Sex ratio is defined as the proportion females at birth. Values must be between 0 and 1. The default is set at 0.5.
- variance
Estimate variance using "binomial" or "bootstrap". The default is set as "bootstrap".
- year_start
A whole number between 1 and 12 indicating the month of the start of the caribou (i.e., biological) year. By default, April is set as the start of the caribou year.
Details
x needs to be formatted in a certain manner. To confirm the input
data frame is in the right format you can use the
bbd_chk_data_recruitment
function. See the vignette("methods", package = "bbouretro") for the
equations used in this function.
User’s can input the assumed proportion of females in the population (to estimate females from adult caribou that have unknown sex) as well as sex ratio at birth.
Examples
calfcow_est <- bbr_calf_cow_ratio(
bboudata::bbourecruit_a,
adult_female_proportion = 0.65,
sex_ratio = 0.5,
variance = "binomial"
)
calfcow_est <- bbr_calf_cow_ratio(
bboudata::bbourecruit_a,
adult_female_proportion = 0.60,
sex_ratio = 0.65,
variance = "bootstrap"
)