Extremes of heat, drought and precipitation depress reproductive performance in shortgrass prairie passerines

Abstract

Climate change elevates conservation concerns worldwide because it is likely to exacerbate many identified threats to animal populations. In recent decades, grassland birds have declined faster than other North American bird species, a loss thought to be due to habitat loss and fragmentation and changing agricultural practices. Climate change poses additional threats of unknown magnitude to these already declining populations. We examined how seasonal and daily weather conditions over 10 years influenced nest survival of five species of insectivorous passerines native to the shortgrass prairie and evaluate our findings relative to future climate predictions for this region. Daily nest survival (n = 870) was best predicted by a combination of daily and seasonal weather variables, age of nest, time in season and bird habitat guild. Within a season, survival rates were lower on very hot days (temperatures ≥ 35 °C), on dry days (with a lag of 1 day) and on stormy days (especially for those species nesting in shorter vegetation). Across years, survival rates were also lower during warmer and drier breeding seasons. Clutch sizes were larger when early spring temperatures were cool and the week prior to egg‐laying was wetter and warming. Climate change is likely to exacerbate grassland bird population declines because projected climate conditions include rising temperatures, more prolonged drought and more intense storms as the hydrological cycle is altered. Under varying realistic scenarios, nest success estimates were halved compared to their current average value when models both increased the temperature (3 °C) and decreased precipitation (two additional dry days during a nesting period), thus underscoring a sense of urgency in identifying and addressing the current causes of range‐wide declines.

Effects of severe weather on reproduction for sympatric songbirds in an alpine environment: Interactions of climate extremes influence nesting success

“…Thus, extreme precipitation events frequently lower nesting success in both high-elevation (e.g., Hendricks andNorment 1991, Decker andConway 2009, present study) and low-elevation environments (Fisher et al 2015, Conrey et al 2016. Open-country birds breeding in warmer environments at lower elevations and latitudes are also susceptible to hot weather over short periods and drought conditions over longer periods (George et al 1992, Bolger et al 2005.…”

“…In temperate biomes, parent birds must make up a thermal deficit or excess of 10-408C or more from ambient conditions by heating and cooling their offspring over a period of several weeks while meeting their own somatic requirements (Conway and Martin 2000a, 2000b. Although cold or inhospitable weather is considered to be an energetic challenge with potential fitness costs (Hendricks and Norment 1991, Martin and Wiebe 2004, 2006, the difference in the ecological costs to birds breeding in normal vs. extreme weather conditions has received little study until recently (Skagen and Yackel Adams 2012, Pipoly et al 2013, Conrey et al 2016. In general, we have little direct knowledge as to which elements of ambient weather constitute ''extreme conditions'' for bird species within or across habitats, which has hampered our ability to refine predictions about the impacts of climate change.…”

Effects of temperature and precipitation on grassland bird nesting success as mediated by patch size

“…In northern Colorado (U.S.A.), hot (≥35°C) or stormy days and drier breeding conditions are associated with lower nest survival for grassland birds (Conrey et al. ). Conversely, years with warmer and wetter conditions promote elevated reproductive success for grassland birds, suggesting indirect benefits of increased grassland productivity (Rotenberry & Wiens ; Chase et al.…”

Ecological and social consequences of bison reintroduction in Colorado

“…For example, the decrease in density by Western Meadowlark across both bison and reference sites can probably be attributed to fluctuations in precipitation during our study period (Niemuth et al, 2008). Other studies have demonstrated decreases in nest survival for shortgrass prairie birds during periods of drought or increased temperatures (Conrey, Skagen, Yackel Adams, & Panjabi, 2016). Other studies have demonstrated decreases in nest survival for shortgrass prairie birds during periods of drought or increased temperatures (Conrey, Skagen, Yackel Adams, & Panjabi, 2016).…”