DOI: 10.5061/dryad.bj852
title: Data from: Predators, energetics and fitness drive neonatal reproductive failure in red squirrels

description: Neonatal reproductive failure should occur when energetic costs of
 parental investment outweigh fitness benefits. However, little is known
 about the drivers of neonatal reproductive failure in free ranging species
 experiencing continuous natural variation in predator abundance and in the
 energetic and fitness costs and benefits associated with parental
 investment. Long-term comprehensive studies are required to better
 understand how biotic, abiotic, and life history conditions interact to
 drive occurrences of reproductive failure in the wild. Using 24 years
 (1987-2011) of reproductive data from a northern boreal population of
 North American red squirrels in southwestern Yukon, we examined the
 effects of predator abundance, energetics (resource availability, ambient
 temperature and litter size), and fitness benefits (probability of
 overwinter juvenile survival and maternal age) on occurrences of neonatal
 reproductive failure (494/2670 reproductive attempts; 18.5%). Neonatal
 reproductive failure was driven by a combination of predator abundance,
 and the energetic and fitness costs and benefits of parental investment.
 The abundance of mustelids and maternal age were positively related to the
 occurrence of neonatal reproductive failure. High energy costs associated
 with a combination of low resource availability and cold ambient
 temperatures or large litters, corresponded to increased occurrences of
 neonatal reproductive failure. However, the strength of these
 relationships was influenced by variation in juvenile overwinter survival
 (i.e. fitness benefits). We provide evidence that predation pressure is an
 important driver of neonatal reproductive failure. In addition, we found a
 trade-off occurs between resource-dependent energetic and fitness costs
 and benefits of raising the current litter to independence
description: Reproductive failure of
 red squirrels and associated measurementsData collected in the
 field from 1989 to 2012 on reproductive failure in red squirrels and
 associated variables. Columns are: LitID- litter ID # in analysis, Grid -
 study area in which squirrel was living, YR - Year of reproductive
 attempt, LN - reproductive attempt number of that year for the female (all
 are the first litter), BDATE - estimated parturition date of litter (based
 on live trap monitoring of females), FoodSup - whether squirrels were
 provided food supplementation (1) or not (0), MOMID - unique ear tag
 numbers of female squirrels, litsize - number of pups in litter, PCI -
 previous years spruce cone index (log transformed), weas - annual average
 number of weasel tracks/100km counted in area, marten - annual average
 number of marten tracks/100km counted in area, pYRSurv - proportion of
 that years cohort of juveniles that survived the winter to the following
 year, cold - coldest 4-day average temperature experienced during the
 first 14 days of lactation (Environment Canada’s National Climate Data and
 Information Archive (www.climate.weatheroffice.gc.ca)), mBY - birth year
 of the female, pred - annual average number of mustelid (marten and
 weasel) tracks/100km counted in area, MAge - maternal
 age.reproductive_failure.csv