Climate is expected to have broad effects on ecological communities, but this occurs in the context of significant daily temperature variation in many localities. Because many ectotherms can restrict activity to thermally suitable places and times, daily temperature variation offers the potential to buffer impacts of warming. Using thermal activity data from a montane ground-nesting ant community, we explore how a simulated increase in temperature is expected to alter the duration of suitable activity windows. Counterintuitively, we found that simulated warming lengthens activity times for cold-active species and shortens activity times for warm-active species. We explain this result through a simulation model in which time elapsed within a range of suitable temperatures is considered as an additive resource. Fundamentally, our model results rely on the fact that the mathematical function that relates time to temperature through a day (Parton-Logan function) is concave before and after noon and convex through the night. These properties are common across terrestrial environments with characteristic deceleration in temperature near both the daily maximum and minimum. Our results suggest that the time of day during which an animal’s activity temperatures occur may be an important, but rarely considered, feature of natural history that contributes to the predicted impact of climate change. In particular, thermally restricted diurnal species may need to compensate for shortened daily activity windows through means such as seasonal shifts or expansions, broadened activity temperatures, or range shifts.

Data Collected June 2015 - October 2015
Sagehen Experimental Forest, CA, USA: (2000m, 39.435583°N, 120.264017° W)

Description: these data were generated using automatic time-sorting pitfall traps that measured temperature at the surface of the soil every 5 minutes and collected ants
were identified to species

Keywords: ants, temperature, activity, ecology, communities, diel rhythms

File 1
TempDataRaw.csv

File Description: Raw data from ant traps with processed sample summary statistics

Column Descriptions
1 {no name} - row index
2 unixStart - time of trap launch in unix time (this is one day before sampling began)
3 insectInterval - length in seconds of insect collection for this time window
4 sample - sample number (1-24) within this trap deployment
5 date - date " month/day/year " note year was 2015
6 time - time of day (hour:minute:second) recorded in 24 hour time
7 tempC - temperature at 1-3 mm above surface recorded by a J-type thermocouple
8 trapID - identifier for individual traps (1 through 14)
9 julianDay - day of year for current sample
10 julianStart - day of year first collection for these 24 samples
11 sampleStart - date and time (month/day/year hour:minute) that this sample began
12 sampleEnd - date and time ((month/day/year hour:minute) that this sample ended
13 dateTime - date and time (month/day/year hour:minute) for this temperature measurement
14 sampleID - identifier for this sample (julian day, trapID, and hour) pasted together
15 meanHrlyTemp - mean temperature C within this sample (1 hour)
16 sdHrlyTemp - standard deviation temperature C within this sample (1 hour)
17 sampleMax - maximum observed temperature C within this sample (1hour)
18 sampleMin - minimum observed temperature C within this sample (1 hour)
19 sampleMiddle - date and time (month/day/year hour:minute) of the middle of this sample (12 hours after beginning)

File 2
TempData_SampleAverages.csv

File Description: sample summary statistics for abiotic variables (hour long samples)

Column Description
1 {no name} - row index original to raw file
2 unixStart - time of trap launch in unix time (this is one day before sampling began)
3 insectInterval - length in seconds of insect collection for this time window
4 sample - sample number (1-24) within this trap deployment
5 date - date " month/day/year " note year was 2015
6 time - time of day (hour:minute:second) recorded in 24 hour time
7 tempC - temperature at 1-3 mm above surface recorded by a J-type thermocouple
8 trapID - identifier for individual traps (1 through 14)
9 julianDay - day of year for current sample
10 julianStart - day of year first collection for these 24 samples
11 sampleStart - date and time (month/day/year hour:minute) that this sample began
12 sampleEnd - date and time ((month/day/year hour:minute) that this sample ended
13 dateTime - date and time (month/day/year hour:minute) for this temperature measurement
14 sampleID - identifier for this sample (julian day, trapID, and hour) pasted together
15 meanHrlyTemp - mean temperature C within this sample (1 hour)
16 sdHrlyTemp - standard deviation temperature C within this sample (1 hour)
17 sampleMax - maximum observed temperature C within this sample (1hour)
18 sampleMin - minimum observed temperature C within this sample (1 hour)
19 sampleMiddle - date and time (month/day/year hour:minute) of the middle of this sample (12 hours after beginning)
20 sampleLocation - identifier code for a set of 24 hourly samples (a location)
21 Names - an attempt number - some traps had technical errors, these were excluded
22 LocationID - identifier code for a set of 24 hourly samples (a location)
23 lon - longitude of trap (decimal)
24 lat - latitude of trap (decimal)
25 litter.g - the mass of leaf litter in grams collected within a 30cm radius of the the trap entrance (dry mass g)
26 nearestPlant - common name of the nearest plant to the trap
27 gap_fraction - the percentage of a hemispherical view (from 10cm above ground) that is open sky
28 solarNoon - time of solar noon for this sampling sample day (m/d/y hour:minute)
29 solarNoonPrev - time of solar noon for the previous day (m/d/y hour:minute)
30 solarNoonNext -time of solar noon for the next day (m/d/y hour:minute)
31 hour - hour of the day of the sample

File 3
locationData.csv

1 {no name} row index for this file
2 litter.g - the mass of leaf litter in grams collected within a 30cm radius of the the trap entrance (dry mass g)
3 nearestPlant - common name of the nearest plant to the trap
4 lon - longitude of trap (decimal)
5 lat - latitude of trap (decimal)
6 gap_fraction - the percentage of a hemispherical view (from 10cm above ground) that is open sky
7 names - an attempt number - some traps had technical errors, these were excluded
8 photo - file name of hemispherical photo from this trap location take at height of 10cm
9 dateIN - date trap installed (month/day/year)
10 timeIN - time trap installed (hour:minute)
11 dateOUT - date trap removed (month/day/year)
12 timeOUT - time trap removed (hour:minute)
13 julianStart - julian day collections began
14 locationID - the location ID code (Julian Start and trap number pasted together)

File 4
antData.csv

1 species - species genus
2 CTmin - mean CT min measured for species (begin at 28C in copper block. drop temperature 1C every 5 minutes. assess at end of 5 minutes if mobile. if not mobile, CT min.
3 CTmin SE - standard error of CTmin for species
4 CTminN - number of ants sampled for CTmin estimate
5 CTmax - mean CT max measured for species (begin at 28C in copper block. raise temperature 1C every 5 minutes. assess at end of 5 minutes if mobile. if not mobile, CT max.
6 CTmin SE - standard error of CTmax for species
7 CTminN - number of ants sampled for CTmax estimate
8 unixStart - the launch time for the trap that collected this ant
9 insectInterval - duration in seconds of the time window this insect was collected within
10 sample - the sample number this insect was collected in within this trap (1-24)
11 date - date insect collected (m/day/year)
12 time - time insect collected (h:m:s)
13 tempC - mean hourly temperature during collection window of this insect
14 trapID - trap ID (1-14) that this insect was collected during
15 julianDay - julian day that this collection was made during
16 julianStart - julian day that this sampling window (24 hours) began
17 sampleStart - date and time (month/day/year hour:minute) that this sample began
18 sampleEnd - date and time ((month/day/year hour:minute) that this sample ended
19 dateTime - date and time (month/day/year hour:minute) for this temperature measurement
20 sampleID - unique identifier for the sampling window this insect was collected within (Julian day, trap, hour)
21 box - number of box sample stored in
22 row - row of box sample stored in
23 col - column of box sample stored in
24 VOUCHER.TAKEN - what species this sample was taken as a voucher for
25 month - the month (month/1/15) that this sample was collected within
26 totalAnts - ants collected alongside this sample
27 antDiv - number of ant species collected in this sample

File 5
sagehen_dailySummaries.csv
data downloaded from Sagehen Experimental Station - tower 1 - 1m above ground

1 {no name} row index for file
2 Date (month/day/year) for weather station data
3 Year
4 julianDay - julian day for weather data
5 dailyMax_tempC - maximum temperature reached for date
6 dailyMin_tempC - minimum temperature reached for date
7 dayLength - time in hours between sunrise and sunset
8 nightLength - time in hours between sunset and sunrise