Experimental evidence that nest orientation influences microclimate in a temperate grassland

Birds exhibit an assortment of behavioral strategies to cope with variable environmental conditions during reproduction, including altering nest construction behaviors. In species building enclosed domed nests, the microclimate within nests is influenced not only by its structure and the surrounding vegetation but also by the orientation of the nest opening. Many grassland-dependent birds build dome-shaped nests with clear directionality of openings. We studied two species in northeastern Kansas, United States that typically orient their nests east to northeast in this region. However, in a drought year, both Grasshopper Sparrows (Ammodramus savannarum) and Eastern Meadowlarks (Sturnella manga) shifted orientations of their nests southward toward prevailing winds. We hypothesized that this shift reduced the deleterious effects of heat stress on parents and developing young by diminishing morning solar radiation and increasing cooling due to the prevailing southerly winds. To test this h..., We conducted the experiment at the Konza Prairie Biological Station (KPBS), a 3487-ha native tallgrass prairie located 15 km south of Manhattan, Kansas (Knapp et al. 1998). The KBPS is managed experimentally as part of the Long-Term Ecological Research program in units subject to multiple combinations of prescribed fire and grazing. The site has a mid-continental climate with mean daily temperatures in recent years of ~13 °C (Macpherson et al. 2008) and the mean maximum daily temperatures during July range from 29.4 °–35.6 °C (Craine et al. 2012). At KPBS, the sun rises 58.63 degrees from the north and sets 301.36 degrees from the north during peak summer, defined in this study as June–August (NOAA Solar Position Calculator, https://gml.noaa.gov/grad/solcalc/). Prevailing winds blow from south to north (Lysenko et al. 1994). There is high interannual variability in summer (May–September) precipitation with a 30-yr rainfall average of 65.2 cm (CV of 29.8%; Knapp et al. 2015). During May–..., , # Experimental evidence that nest orientation influences microclimate in a temperate grassland

We present the south- and east- facing nest temperature (degrees Celsius), humidity (% relative humidity), and wind speed (m/s) for experimentally placed Grasshopper sparrow and Eastern meadowlark nests (n= 34). These data also include the difference between east- and south- facing nests for each of these variables (east - south).

## Description of the data and file structure

##### AllTempHumid - all temperature and humidity values over a 24 hour period during the experiment (47 days during summer 2019) Variable definitions:

* hour: The hour of the day when the measurement was taken. We extracted this information without the minutes to reduce noise. Measurements were taken every ten minutes; in the models, we used average hourly values for each day.
* Nest_ID: Identification of specific nest pairs. The number at the beginning denotes the placement order of the nest pairs. The four le...