Field Guide 93 · Small game biologyFox squirrel · Michigan · Civil dawn
Adrian fox squirrels tracked dawn and spent about 7 hours out
FDR Research Desk · Field-craft, method, and evidencePublished
A fox squirrel busy in the trees late in the morning and quiet by midafternoon may already be back in a nest or sitting still. On about 198 acres (80 ha) of university and Motherhouse grounds in rural Adrian in Lenawee County, Wassmer and Refinetti timed nest use with temperature collars. Their 2016 paper in PLoS ONE followed 14 fox squirrels across 25 collar preparations and 1385 recording days from October 2011 through May 2015.
Our read is to plan the look for late morning and midday after the first exit. An all-day sit does not match this sample. Seasonal averages put that first exit 1.5 to 2.2 hours after dawn. The authors set day length from civil dawn and civil dusk. Time out of the nest stayed near 7 hours across seasons in their summary. Our reading of one spring record is that those hours need not fall in a single block. That male went back to the nest around noon for a few hours and came out briefly once more before night.
Summer exits came 2.1 hours earlier on the study clock than winter exits. The authors read that shift as the squirrels tracking dawn as the days grew longer and shorter. By our arithmetic the 9-hour winter day at this site left about 2 hours of daylight beyond the roughly 7 hours out. The 15-hour summer day left about 8 hours. An all-day plan overshoots this sample most on the long summer days. The squirrels occasionally left the nest at night, so the leftover daylight is approximate.
STEP 1 · Nest clock
Collar temperature separated the nest from the outside
Only squirrels that kept returning to the traps were collared, because the loggers had to be recovered. In the nest the collar warmed toward body temperature. Outside the nest the collar cooled and the trace jumped as the squirrel moved through different air. Two one-hour watches of one female and one male tied those jumps mostly to moving and grooming. Steady collar temperature lined up with resting and vigilance.
The authors did not quantify outside activity for every squirrel. Watches of several animals over several hours found them sitting or lying quietly for 45 to 67 percent of the time outside the nest. Our read is that a count of movement alone misses a squirrel that is out and still. On this pattern a quiet midday can be a return to the nest or a long sit.
STEP 2 · Dawn delay
Average first exits fell 1.5 to 2.2 hours after dawn
The first daily exit was 2.1 hours earlier in summer than in winter on local clock time, and that seasonal test was significant. The authors ignored daylight-saving shifts so a clock change would not bend the series. As hours after dawn the seasonal averages fell between 1.5 and 2.2. The seasonal test on that delay was not significant. The paper prints the same test statistic for a separate measure of day-to-day consistency. We take the non-significant dawn result as the authors' statement. A non-significant test still leaves a real seasonal difference possible.
The squirrels typically left after dawn and returned before dusk, including in winter when this site had about 9 hours of light. Our read is to anchor any comparison on civil dawn for the date and place. Wall-clock time during daylight-saving months will not match the 2.1-hour shift.
STEP 3 · Same span
This sample did not show a longer summer outing
Time spent out of the nest showed no significant seasonal difference, and the summary figure was about 7 hours a day. That test cannot prove the span never changes. It gave no sign of a longer summer outing in this sample.
These squirrels differed less on hours out than on exit counts. The coefficient of variation was 0.21 for time out of the nest and 0.79 for exits per day. Our read is that a second trip does not by itself mean more time out, since warm-season excursions rose while time out showed no detected seasonal change.
The authors suggest these fox squirrels may follow a slow life history with long rests in the trees and short periods of ground activity each day.
STEP 4 · Warm months
Nest exits rose slightly while the day stayed mostly one bout
The squirrels left the nest an average of 1.3 times a day. Spring and summer averaged 1.4 excursions a day. Autumn and winter averaged 1.1. The authors called the difference slight, and the test was significant. Some days showed a morning bout and an afternoon bout. That split faded when the days were averaged. The main pattern stayed unimodal all year.
The authors compared only the length of the active period with an older gray squirrel study by Tester, because the methods differed. In that account gray squirrels started before dawn and quit after dusk even on long summer days. The shortest winter activity Tester observed was 8 hours. The authors called that one hour longer than their figure of about 7 hours out of the nest. Our read is to time fox squirrels from fox squirrel records gathered the same way.
STEP 5 · Your ground
A nest note records the exits you detect
Our observation is optional. On mornings you can watch one leaf nest or den from civil dawn, note the first exit you see in hours after civil dawn. Skip mornings you arrived later, because you could not see an earlier exit. Note a last return only if you were watching when it happened. Note a midday return or a second trip if you see it. Repeat on other days in that season when you are already there. Compare the middle of your first-exit times with the Adrian seasonal averages of 1.5 to 2.2 hours. Single days varied in the collar records, so one odd morning does not settle the place.
What you can establish is the timing you detected at that nest across those days. You cannot name the squirrel. You cannot reproduce collar occupancy from an unmarked nest. You cannot recover the Adrian averages or a wider population result. You cannot read hunting success from the note.
Our rule is to set the Adrian clock aside for that ground if most detected first exits land well before 1.5 hours after civil dawn or well after 2.2 hours. Also set it aside if you keep seeing squirrels out of nests into late afternoon on most long summer days. Several unmarked squirrels on staggered schedules can look like one long day, so this cannot show any one squirrel's time out.
These collars were on squirrels that returned to traps on one developed site. The authors say the sample may be limited to animals with small home ranges, and they did not measure ranges. The sitting share came from several squirrels watched for several hours. Day-to-day changes might reflect weather or a predator encounter, and the authors left that open. This study does not set season dates or shooting hours. Check the state wildlife agency before you treat any clock as a hunting plan. On a campus or in a park, keep the work as observation.
NOTES AND SOURCES
Fully Drawn Research is an independent data analysis desk, not affiliated with any state wildlife agency, transportation agency, mapping provider or outfitter. This guide reports published research and FDR's reading of it. The field observations proposed here were not tests of hunting or fishing success.
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