Changing habitat associations of a thermally constrained species, the silver‐spotted skipper butterfly, in response to climate warming

Abstract

Summary1. The impact of climate change on the distribution, abundance, phenology and ecophysiology of species is already well documented, whereas the influence of climate change on habitat choice and utilization has received little attention. Here we report the changing habitat associations of a thermally constrained grassland butterfly, Hesperia comma , over 20 years. 2. Between 1982 and 2001-2, the optimum percentage of bare ground within habitat used for egg-laying shifted from 41% to 21%. 3. Egg-laying rates are temperature-dependent and females actively adjust microhabitat usage in response to temperature variations; relatively warmer host plants are chosen or oviposition at low ambient temperatures, and cooler host plants at high ambient temperatures. 4. Climate warming has increased the availability of thermally suitable habitat for H. comma at the cool, northern edge of the species' distribution, therefore increasing: (a) egg-laying rate and potentially the realized rate of population increase; (b) effective area of habitat patches as more microhabitats within a given vegetation fragment are now suitable for egg-laying; (c) buffering of populations against environmental variation as eggs are laid within a wider range of microhabitats; and (d) the number of habitat patches in the landscape that are currently available for colonization (including the use of more northerly facing aspects; Thomas et al ., Nature , 2001, 411 , 577-581). 5. Conservationists often assume the habitat requirements of a species to be constant, and manage habitats to maintain these conditions. For many species, these requirements are likely to change in response to climate warming, and care must be taken not to manage habitats based on outdated prescriptions.

The effect of temperature and habitat quality on abundance of the Glanville fritillary on the Isle of Wight: implications for conservation management in a warming climate

“…Our result also explains why species at northern limits of their range often experience dramatic population fluctuations Davies et al 2006;Oliver et al 2012a): hostplants on cooler slopes and aspects can be utilised during warm years, resulting in temporary increase in both the abundance of individual populations and the area of occupied habitat.…”

“…However, temperature driven changes in habitat associations remain poorly understood (Davies et al 2006;Turlure et al 2010), yet comprehending such changes are essential for adaptive conservation management (Sutherland 1998;Roy & Thomas 2003). Therefore, an important unanswered question is whether temporal variation in habitat quality, or ambient temperature is the stronger predictor in determining species abundance.…”

Accounting for habitat when considering climate: has the niche of the Adonis blue butterfly changed in the UK?

“…The role of climate change in the range expansion of the butterfly Hesperia comma in the UK has been extensively studied (Davies et al 2005;Thomas et al 2001;Wilson et al 2009Wilson et al , 2010. Davies et al (2006) show that a key factor enabling this expansion was a widening of H. comma's realized larval niche under warmer air temperatures. However, since the 1980s the habitat of many H. comma sites has been managed to optimise larval habitat (as defined by Thomas et al 1986), and so warmer temperatures and habitat management will have been acting on H. comma populations concurrently.…”

“…Global warming is an equally well-documented driver of change in insects, affecting phenology, voltinism, niche breadth, population stability and density, and geographic ranges (Altermatt 2010;Davies et al 2006;Hill et al 2002;Oliver et al 2012;Parmesan 2006;Parmesan et al 1999;Roy et al 2001;Roy and Sparks 2000;Thomas et al 2001).…”

The importance of altitude and aspect for breeding WhinchatsSaxicola rubetrain the uplands: limitations of the uplands as a refuge for a declining, formerly widespread species?

“…Environmental factors such as aspect, topography and altitude can influence local and microclimatic conditions that determine the suitability of otherwise apparently appropriate habitats for different species (Davies et al 2006, Bennie et al 2008, Bradbury et al 2011. For species that are declining within their lower altitudinal range, it might be expected that there will be environmental constraints that limit the suitability of habitats within their remaining upland range as a result of lower ambient temperatures and generally greater levels of exposure.…”