Data from: Divergent estimates of herd-wide caribou calf survival: ecological factors and methodological biases
Cite this dataset
Ellington, Edward Hance; Lewis, Keith P.; Koen, Erin; Vander Wal, Eric (2021). Data from: Divergent estimates of herd-wide caribou calf survival: ecological factors and methodological biases [Dataset]. Dryad. https://doi.org/10.5061/dryad.xgxd254db
Staff from the government of Newfoundland and Labrador monitored 540 radio-collared woodland caribou calves across eight herds during the population growth phase (1979–1997) and 635 radio-collared calves across five herds during the population decline phase (2002–2014). Capture methods are described in Rayl et al. (2014) and Mumma et al. (2019).
Staff from the government of Newfoundland and Labrador conducted 249 herd composition surveys for 26 woodland caribou herds across Newfoundland from 1979–2014, except for the years 1998–2001. Herd composition survey methods varied both temporally and spatially from 1979–2014 and we did not necessarily know the exact methodology used for a specific herd year. We summarize below a broad picture of the methods used. Between the months of September and December, observers (typically two plus the pilot) flew rotary-wing (and perhaps in earlier years, fixed-wing) aircraft over an area believed to be where herds were currently located. Occasionally, telemetry data were used to estimate where a woodland caribou herd was located and in other years, the historic position of the herd was used. Herd composition surveys were typically conducted over one day but occasionally surveys were conducted over multiple days if weather was poor or woodland caribou were difficult to locate. For larger herds, the herd composition survey was a sampling effort but for smaller herds total counts were occasionally conducted. The crew counted the number of woodland caribou within basic demographic groups: adult male, adult female, and calf, and if needed the pilot would use the aircraft to separate large groups into more manageable sub-groups for counting.
Staff from the government of Newfoundland and Labrador also conducted herd composition surveys during the months of May and June to estimate the proportion of parous cows (an estimate of fecundity). Cows with calves close by or with visible signs of pregnancy were considered parous.
Within the Rdata file are three dataframes:
TELE_DATA - this contains caribou calf survival data
HCS_DATA_FALL - this contains caribou herd composition survey data from the fall
HCS_DATA_SPR - this contains caribou herd composition survey data from the spring
Please feel free to contact me with any questions about these datasets.