Impacts of a Severe Drought on Grassland Birds in Western North Dakota

Abstract

We studied the effect of a severe drought on the population dynamics and community structure of grassland birds in western North Dakota. During the spring and summer of 1988 the northern Great Plains suffered one of the warmest, driest periods in its recorded history. We compared the changes in bird populations and nesting productivity over a 3-yr period before, during, and after the drought. Total grassland bird density declined 61% (P < .05) between June 1987 and June 1988. Densities of six of eight common species declined significantly during the drought. Populations of all but two species recovered in 1989 and total bird density in June 1989 did not differ significantly from June 1987. Species richness and species diversity both declined significantly during the drought and recovered to predrought levels in 1989. Species richness declined more on fair condition than on good condition range during the drought. Vesper Sparrow (Pooecetes gramineus) hatching success, number of young fledged per successful nest, and nesting success were significantly lower in 1988 than either 1987 or 1989. Clutch size did not differ among the three years. The decline in nesting success in 1988 was primarily due to nest abandonment during incubation. Nesting of Vesper Sparrows, Horned Larks (Eremophila alpestris), and Western Meadowlarks (Sturnella neglecta) ended abruptly in mid-June 1988 during a period of extremely hot weather. In 1987 and 1989, nesting continued into July. Despite substantial reductions in bird density and productivity during the drought, many species recovered to predrought levels 1 yr following the drought. This suggests that year-to-year fluctuations in densities of some of these species may not be tightly linked to short-term changes in local productivity. However, sequential years of low productivity may have more substantial effects on these short-lived species. Thus, if drought conditions in North American grasslands become more frequent, as some climate models predict, there could be related changes in the avifauna of the region.

Mapping evaporative water loss in desert passerines reveals an expanding threat of lethal dehydration

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Drought and Cooler Temperatures Are Associated with Higher Nest Survival in Mountain Plovers

“…To limit the number of models evaluated, we developed a set of a priori biological hypotheses and used these to choose explanatory variables (Table 1) and guide construction of the model set (Appendix 1). The types of weather variables that we considered to have the greatest potential influence on DNS, based on the scientific literature for plovers and other grassland and shrubsteppe bird species, were daily precipitation, daily temperature, seasonal precipitation, and seasonal temperature (Rotenberry and Wiens 1989, George et al 1992, Dinsmore et al 2002. Within each of these four categories, we included variables such as total daily precipitation, daily maximum temperature, total precipitation during the breeding season, and average daily maximum temperature during the breeding season, respectively.…”

Reproductive success of songbirds and waterfowl in native mixed-grass pasture and planted grasslands used for pasture and hay

“…Distribution and density of grassland birds are influenced by current-year precipitation (Wiens 1974, Cody 1985, George et al 1992, Niemuth et al 2008, Ahlering et al 2009). …”