Fig 1.
Stations providing recent and historical microclimatic data (K1) and long-term climatic data (C1 and D1) on Niwot Ridge, Boulder County, Colorado, west of Colorado Highway 72 (CO 72). Map tiles by Stamen Maps (http://stamen.com) provided under CC BY 3.0 (http://creativecommons.org/licenses/by/3.0). Data by OpenStreetMaps (http://openstreetmap.org) provided under ODbL (http://www.openstreetmap.org/copyright).
Table 1.
Datasets used to compare recent and historical temperatures at an American pika study site on Niwot Ridge, Colorado, USA.
Fig 2.
Temperature statistics calculated from recent data.
Discrete (timed-interval) data from each day at the K1 site were interpreted as continuous data using a cubic-spline smooth in a generalized additive model (GAM), to allow direct comparisons with historical data, which were recorded continuously by thermographs. This example shows GAM fits for August 2013. Symbols represent statistics calculated from each daily fit, as defined in Table 2.
Table 2.
Temperature statistics compared between historical and recent datasets.
Table 3.
Monthly summary statistics from recent (2009–2021) microclimatic data collected by the shallow sensor at K1, just below the surface of the talus.
Fig 3.
Recent and historical monthly maximum and minimum temperature metrics.
Values shown are absolute monthly maximum or minimum temperatures (panels A-C) as well as monthly averages of daily maximum or minimum temperature (panels D-F). All data were recorded at K1 in a pika study site on Niwot Ridge (Boulder County, Colorado, USA). Time periods for historical data (black symbols) and recent data (colored symbols) are shown in Table 1. Historical maximum temperatures (black dots) and minimum temperatures (black triangles) are compared with recent maximum temperatures (red dots) and minimum temperatures (blue triangles) using a cubic-spline smooth to estimate recent means (colored curves) and 95% confidence intervals (shaded regions).
Fig 4.
Recent and historical monthly mean temperatures.
Values shown are the daily means of the absolute maximum and minimum temperature, averaged across the days in each month (Table 2). All data were recorded at K1 in a pika study site on Niwot Ridge (Boulder County, Colorado, USA). Time periods for historical data (black symbols) and recent data (colored symbols) are shown in Table 1. Historical mean daily temperatures (black dots) are compared with recent mean daily temperatures (red dots) using a cubic-spline smooth to estimate recent means (red curves) and 95% confidence intervals (shaded regions).
Fig 5.
Recent and historical days above freezing (0° C).
All data were recorded at K1 in a pika study site on Niwot Ridge (Boulder County, Colorado, USA). Time periods for historical data (black symbols) and recent data (red symbols) are shown in Table 1. Historical data (black dots) are compared with recent data (red dots) using a cubic-spline smooth to estimate recent means (colored curves) and 95% confidence intervals (shaded regions).
Fig 6.
Recent temperatures recorded at K1 and surrounding pika haypiles.
All data were recorded during 2009–2021 at shallow positions in talus within a pika study site on Niwot Ridge (Boulder County, Colorado, USA). Temperature metrics (Table 2) at K1 (colored symbols) and at pika haypiles throughout the surrounding Krear study site (gray symbols) are compared using a cubic-spline smooth to estimate means (colored curves) and 95% confidence intervals (shaded regions).
Fig 7.
Recent and historical free-air temperatures at K1 and C1.
Data recorded at the K1 pika study site and C1 subalpine weather station on Niwot Ridge (Boulder County, Colorado, USA). Means (curves) and 95% confidence intervals (shaded regions) were estimated using a cubic-spline smooth. See Table 1 for years associated with each period, and Table 2 for temperature metrics.
Fig 8.
Recent and historical free-air temperatures at K1 and D1.
Data recorded at the K1 pika study site and D1 alpine weather station on Niwot Ridge (Boulder County, Colorado, USA). Means (curves) and 95% confidence intervals (shaded regions) were estimated using a cubic-spline smooth. See Table 1 for years associated with each period, and Table 2 for temperature metrics.
Fig 9.
Recent and historical number of days above freezing (0° C).
Data from the K1 pika study site and weather stations C1 (subalpine) and D1 (alpine) on Niwot Ridge (Boulder County, Colorado, USA). Recent weather station data (gray dots) were compared with recent K1 data (red dots) in panels A and C, while historical weather station data (gray dots) were compared with historical K1 data (black dots) in panels B and D. Means (curves) and 95% confidence intervals (shaded regions) were estimated using a cubic-spline smooth. See Table 1 for years associated with each period, and Table 2 for temperature metrics.