Diurnal and seasonal fluctuations in wood ant (Formica polyctena) nest temperature in two geographically distant populations along a south – north gradient

Abstract

Temperature changes were recorded continuously in eleven nests of Formica polyctena located in Southern Finland and the Czech Republic. Nest temperatures were recorded in the Czech site from 2003 to 2005 and in Finland during 2004 -2005. Seasonal changes in nest temperature were very similar in both locations.During summer, the ants maintained a relatively high and constant temperature in their nest in both locations. Summer nest temperatures in Finland were higher than those in Czech during 2004 -2005 but did not differ from those in Czech during 2003 -2004. This indicated that the geographical differences were less important than difference between seasons. Nest temperature peaked in June. During summer, daily temperature fluctuations were significantly lower in Finland than in Czechia probably due to shorter nights in Finland. Apparent differences in daily temperature patterns were found in nests with different moisture in both locations. In dry nests, temperature peaked in the evening and decreased overnight, whereas the apparent increase was delayed to the night in wet nests. The spring increase in temperature in wet nests was much steeper that that in the dry ones when whole spring period is considered. During one day, temperatures fluctuated much more in dry nests than in wet ones. These differences seem to be caused by differences in thermal capacity between dry and wet nests.

Impact of vegetation removal on the temperature and moisture content of red wood ant nests

“…Similar pattern was confirmed by ant nests in Rodlen, but the amplitude was much lower and its peak was detected at 1 p.m. There is an obvious shift in comparison with other studies (Frouz, 2000;Frouz and Finer, 2007) where it was detected at about 3 p.m. or later. The ant hill identified as the wettest showed an almost straight curve which resembled the relationship in nests characterized by more than 35 % moisture; some of them exceed even 80 % (Frouz, 1996(Frouz, , 2000Frouz and Finer, 2007).…”

“…These parameters in conjunction with ant metabolic heat production are the main factors for temperature maintenance (Frouz, 2000). Such small, dry nests are consequently characterized by temperature increase during the day and its decrease during the night (Frouz, 2000;Frouz and Finer, 2007). Similar pattern was confirmed by ant nests in Rodlen, but the amplitude was much lower and its peak was detected at 1 p.m.…”

“…In the locality of Rodlen ant hills of F. polyctena are smaller in comparison with ant hills mentioned in other studies (Frouz, 2000;Frouz and Finer, 2007). Their nest moistures were lower and equal in upper parts as well as in central parts; therefore, these ant hills can be characterized as "dry" (Frouz, 1996).…”

“…The ant hill identified as the wettest showed an almost straight curve which resembled the relationship in nests characterized by more than 35 % moisture; some of them exceed even 80 % (Frouz, 1996(Frouz, , 2000Frouz and Finer, 2007). Although our studied nests were colder (in comparison with many authors such as Martin, 1987;Rosengren et al, 1987;Bristow et al, 1992;Frouz 1996Frouz , 2000Lamprecht, 2003;Frouz and Finer, 2007, who reported temperatures higher than 258C) and showed small temperature fluctuation, the direct impact of air temperature on nest temperature was confirmed (GallØ, 1973;Coenen-Stass et al, 1980;Martin, 1987;Frouz, 1996Frouz, , 2000. We can assume that this pattern is typical for small nests, like those in Rodlen with the height about 30 -65 cm (diameter 120 -250 cm).…”

“…All dataloggers monitored temperature and moisture continuously at 1 h intervals from 3 March to 7 September 2007. The same date, April the 16 th , was chosen pursuant to Frouz and Finer (2007) to demonstrate daily temperature fluctuations.…”