Spatial synchrony at the extremes: Tail-dependence in temperature drives
tail-dependence in birds’ spatial synchrony across North America
Abstract
Environmental change is becoming synchronous across sites with frequent
emergence of extremes in recent years, with alarming potential impacts
on species’ synchronous abundance over large scales. With 23 years of
breeding bird survey data across North America, we found that some birds
are becoming synchronously rare across sites, while others are becoming
synchronously common. We evaluated the relative importance of two
co-occurring mechanisms (environment-driven and dispersal-driven) to
explain such spatial synchrony in extreme low or high abundance (i.e.,
tail-dependent synchrony). We found that spatial synchrony in
temperature extremes (i.e., tail-dependence in climate) was the major
driver for birds’ tail-dependent spatial synchrony up to 250 Km. In
addition, temperature extremes and dispersal trait both favored
synergistically some species making them synchronously common across
sites. In a rapidly changing environment, these findings highlight the
importance of considering synchronized climatic extremes to assess
species’ tail-dependent spatial synchrony across large scale.