Temperature and territoriality in the Duke of Burgundy butterfly, Hamearis lucina

Abstract

The Duke of Burgundy butterfly (Hamearis lucina) has undergone severe declines over the last four decades. However, in recent years the UK population appears to have begun expanding again. This is likely to be due to beneficial management, although a warming regional climate may also have contributed to the resurgence of this spring-flying species. In this study, we investigated the effect of air temperature on the flight behaviour of adult male Duke of Burgundy butterflies. We also looked at the ability of adult males to behaviourally thermoregulate their body temperature and assessed their tendency to remain within small established territories. Increasing air temperature lead to a marked increase in the number and duration of flights associated with territorial behaviour but had no significant effect on other flights. This suggests that high temperatures are particularly important for sustaining energetically-demanding flights involved in territory defence and mate interception, which could impact the reproductive potential of Duke of Burgundy populations. We also found that butterflies had only a limited ability to regulate their body temperature behaviourally and may, therefore, be especially dependent on suitable environmental conditions to maintain the right temperatures for these flights. During observations, most males also remained confined to a few square meters within their territories, which could further restrict butterfly ability to thermoregulate by limiting relocation to other habitat types. However, we did find more males to leave the confines of their territories than expected from reports in previous studies. Our findings highlight the key role that warm, sheltered locations on reserves have in supporting the Duke of Burgundy. If this traditionally poor disperser is to take advantage of a warmer climate and extend its range North, a close network of such areas, appropriately managed, may be critical.

How butterflies keep their cool: Physical and ecological traits influence thermoregulatory ability and population trends

“…As a cold‐adapted species, it would be expected to be better adapted to warming itself up at cooler temperatures than cooling down at higher temperatures. The Duke of Burgundy H. lucina has an early spring flight season (late April to late May; Thomas & Lewington, 2016), but is reliant upon warm, sheltered habitat patches for male territory defence (Hayes et al., 2019; Turner et al., 2009). However, beyond its choice of microhabitat, our data indicate that the Duke of Burgundy H. lucina may have very poor buffering ability, which could explain why populations of this species seem particularly sensitive to habitat management changes that could influence the local microclimate (Hayes et al., 2018; Turner et al., 2009).…”

“…We found a clear difference in the degree to which different species used microclimate selection versus behavioural thermoregulation to buffer their thoracic temperature. Butterflies show a number of mechanisms for behavioural thermoregulation (Kemp & Krockenberger, 2002;Pivnick & McNeil, 1986;Rutowski et al, 1994;Wasserthal, 1975), and an ability to select cooler or warmer microhabitats (Hayes et al, 2019;Kleckova & Klecka, 2016;Kleckova et al, 2014;Rutowski et al, 1994;Suggitt et al, 2012). (Asher et al, 2001).…”

“…In contrast, in hotter conditions, butterflies can adopt postures that reduce the surface area exposed to the sun or that reflect more sunlight (Dreisig, 1995;Rutowski et al, 1994), thus reducing body temperature. Microclimate selection is also common, with individuals selecting sunny locations to warm up or shady locations to cool down (Hayes et al, 2019;Ide, 2010;Kleckova & Klecka, 2016;Kleckova, Konvicka, & Klecka, 2014).…”

“…For example, temperature can directly affect the speed of insect life cycles (Rebaudo & Rabhi, 2018; Wilson & Maclean, 2011) and reproductive rates, affecting population growth rates (Mills et al., 2017). Higher temperatures can also change butterfly activity patterns and facilitate more frequent, longer or more effective territorial and mate‐locating behaviours, potentially increasing breeding success (Advani, Parmesan, & Singer, 2019; Hayes, Hitchcock, Knock, Lucas, & Turner, 2019; Ide, 2010; Rutowski, Demlong, & Leffingwell, 1994).…”

“…In contrast, in hotter conditions, butterflies can adopt postures that reduce the surface area exposed to the sun or that reflect more sunlight (Dreisig, 1995; Rutowski et al., 1994), thus reducing body temperature. Microclimate selection is also common, with individuals selecting sunny locations to warm up or shady locations to cool down (Hayes et al., 2019; Ide, 2010; Kleckova & Klecka, 2016; Kleckova, Konvicka, & Klecka, 2014). Over slightly larger spatial scales, individuals can also select a microhabitat with the preferred temperature (Dreisig, 1995; Rutowski et al., 1994), enabling individuals to maintain their body temperature under shifting climatic conditions (Kleckova et al., 2014).…”