DOI: 10.5061/dryad.cm586
title: Data from: The natural history of the South Hills crossbill in relation to its impending extinction

description: Increasingly, the species that we discover will be uncommon, area
 restricted, and vulnerable to extinction. I describe the natural history
 of a newly discovered seed-eating finch from the Rocky Mountain region,
 the South Hills crossbill (Loxia curvirostra complex). It relies on seeds
 in the closed cones of the fire-adapted Rocky Mountain lodgepole pine
 (Pinus contorta latifolia) and is found only in the higher elevations of
 two small mountain ranges in southern Idaho. Here crossbills and pine are
 engaged in a coevolutionary arms race. Although most of the seeds remain
 secured within the cones for decades until the heat of a stand-replacing
 fire causes the cone scales to separate, seeds become accessible to
 crossbills slowly as cones weather and gaps form between some of the
 scales. However, hot days (≥32°C), especially four or more hot days, seem
 to mimic the effect of fire, apparently causing the immediate release of a
 fraction of the seeds. Such events caused a 20% annual decline in
 crossbills that lasted up to 4 years and an 80% decline in the population
 between 2003 and 2011. This is an example of a novel trophic mismatch
 between a consumer and its resource caused by a shift in the phenology of
 the resource arising from climate change. Not only do these phenological
 shifts have the potential to cause seed consumers to decline, these shifts
 are also likely to cause reduced recruitment of the plants. The South
 Hills crossbill is especially vulnerable and will likely go extinct this
 century before lodgepole pine is extirpated from the South Hills.
description: Days with temperatures
 above 32 degrees CThe dates and maximum
 temperatures at the Magic Mountain SNOTEL site when temperatures reached
 32 degrees C between 1989 and 2015.hot days 1998 to
 2015.xlsxBasal area of lodgepole
 pine at 67 locations in South HillsThis file contains the
 data used to estimate basal area at 67 locations in the South Hills, Idaho
 in 2002 and 2013. The first column is plot identifier, then its latitude,
 longitude, numbers of lodgepole pine within a 20-m radius in 2002 and
 2013, the mean DBH of the these trees, and estimated basal
 areas.Tree
 basal areas data .xlsxdistance data, crossbill
 density estimates 2003-2015These data were used to
 estimate the density of crossbills between 2003 and 2015. The first 4
 columns represent the raw data: year of survey, plot identifier, distance
 to the nearest group of crossbills, and the number of South Hills
 crossbills in the group; blanks indicate no crossbills were observed).
 Columns 6-9 represent estimates of crossbill densities from the data in
 the first 4 columns (year, mean, lower 95% confidence limit, and upper 95%
 confidence limit). Columns 10 and 11 represent the mean annual and spring
 temperatures for the preceding year using data from the Magic Mountain
 SNOTEL site in the South Hills, Idaho.Annual cone production
 dataThe first 17 columns
 represent the raw cone data, whereas columns 19-22 represent the summary
 data shown in figure 7. Column 1 is the tree identifier, column 2 is the
 branch number (5 branches were sampled from each tree), and columns 3-17
 represent the number of cones from each year on each
 branch.Cone opening
 temperaturesThis file provides the
 mean cone opening temperatures for 1-11 year-old cones from 30 trees
 (column 2), and the mean cone opening temperatures for 15-20 year-old
 cones from 32 trees (column 3). These are the data used to produce the
 inset in figure 9.Cone
 temperaturesThese are the maximum
 surface temperatures of cones from one tree in the South Hills, Idaho
 recorded in June 2015. The date, the time, the maximum temperature on the
 cone surface, and the corresponding temperature at the nearby Magic
 Mountain SNOTEL site are provided. These data are shown in figure
 9.