Gustine D, Barboza P, Adams L, Griffith B, Cameron R, Whitten K (2017) Advancing the match-mismatch framework for large herbivores in the Arctic: Evaluating the evidence for a trophic mismatch in caribou. PLoS ONE 12(2): e0171807. doi:10.1371/journal.pone.0171807
Abstract
Climate-induced shifts in plant phenology may adversely affect animals that cannot or do
not shift the timing of their reproductive cycle. The realized effect of potential trophic ªmismatches
º between a consumer and its food varies with the degree to which species rely on
dietary income and stored capital. Large Arctic herbivores rely heavily on maternal capital to
reproduce and give birth near the onset of the growing season but are they vulnerable to trophic
mismatch? We evaluated the long-term changes in the temperatures and characteristics
of the growing seasons (1970±2013), and compared growing conditions and dynamics
of forage quality for caribou at peak parturition, peak lactation, and peak forage biomass,
and plant senescence between two distinct time periods over 36 years (1977 and 2011±13).
Despite advanced thaw dates (7−12 days earlier), increased growing season lengths (15
−21 days longer), and consistent parturition dates, we found no decline in forage quality and
therefore no evidence within this dataset for a trophic mismatch at peak parturition or peak
lactation from 1977 to 2011±13. In Arctic ungulates that use stored capital for reproduction,
reproductive demands are largely met by body stores deposited in the previous summer
and autumn, which reduces potential adverse effects of any mismatch between food availability
and timing of parturition. Climate-induced effects on forages growing in the summer
and autumn ranges, however, do correspond with the demands of female caribou and their
offspring to gain mass for the next reproductive cycle and winter. Therefore, we suggest the
window of time to examine the match-mismatch framework in Arctic ungulates is not at parturition
but in late summer-autumn, where the multiplier effects of small changes in forage
quality are amplified by forage abundance, peak forage intake, and resultant mass gains in
mother-offspring pairs.