A Global Perspective on Conserving Butterflies and Moths and Their Habitats

14 A global perspective on conserving butterflies and moths and their habitats Thomas Merckx1, Blanca Huertas2, Yves Basset3 and Jeremy Thomas4 1Wildlife Conservation Research Unit, Department of Zoology, Recanati-Kaplan Centre, University of Oxford, Oxford, UK 2Life Sciences Department, The Natural History Museum, Cromwell Road, London, UK 3Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Peru 4Department of Zoology, University of Oxford, Oxford, UK Just living is not enough, said the butterfly, one must have sunshine, freedom and a little flower. — Hans Christian Andersen Introduction The order represents a mega-diverse radiation of almost exclusively phytophagous insects, probably correlated with the great diversification of Lepidoptera are one of the four major insect flowering plants since the Cretaceous (Menken orders, and one of the best studied invertebrate et al. 2010). They provide many vital and eco- groups, containing over 160,000 described species nomically important services within terrestrial and an estimated equal number of undescribed ecosystems (e.g. nutrient recycling, soil forma- species, arranged in 124 families (Kristensen et al. tion, food resources and pollination). The scale 2007). Lepidoptera occupy all except the very of these contributions is illustrated by the coldest terrestrial regions, but the Neotropics and estimate that blue tit (Parus caeruleus) chicks Indoaustralian region have five times more consume at least 35 billion caterpillars each year species per unit area than the Palaearctic and in the UK alone (Fox et al. 2006). Lepidoptera Nearctic, and three times more than the also have considerable human significance, both Afrotropical region (Heppner 1991). They are economic and scientific. A growing industry scale-winged insects, traditionally divided into farms pupae for supply to butterfly houses across three major assemblages: micro-moths, butter- the world. One moth species has been domesti- flies and macro-moths (Kristensen et al. 2007). cated in order to provide silk (i.e. Bombyx mori Key Topics in Conservation Biology 2, First Edition. Edited by David W. Macdonald and Katherine J. Willis. © 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd. 0001738427.INDD 239 1/21/2013 3:38:54 PM 240 T. MERCKX, B. HUERTAS, Y. BASSET AND J. THOMAS from the wild B. mandarina). For scientists, changed dramatically since the 1850s. Some the group offers a model system valuable to species have increased their range but most studies of biodiversity conservation, ecology, have declined, and 7% of British species are ethology, genetics, (co)evolution and systemat- extinct. The mean decline in butterflies has been ics (Samways 1995; Boggs et al. 2003). an order of magnitude greater than that of birds Human appreciation of the beauty and or vascular plants (or, where monitored, mam- vulnerability of (especially) butterflies has grown mals), whether measured at the scale of single exponentially in recent decades, particularly in sites, regions or the entire nation (Thomas et al. developed nations. For example, among the 40 2004). Moreover, until the recent application of national biodiversity mapping schemes extant in ecological principles to conservation described the UK, more than 2.5 million records were sub- below, local extinction rates on nature reserves mitted for Lepidoptera thanks to the work of the often exceeded those on commercially managed Centre for Ecology and Hydrology, Rothamsted land, in sharp contrast to the stability achieved Research and Butterfly Conservation (BC) UK, for vertebrates and plants (Thomas 1991). with key input from amateur enthusiasts The four methods of assessment available in ( butterflies 2.2 m; macro-moths 384 k) prior to the UK (Red Data Books (RDBs), species sur- 2000, roughly double the number received for veys, mapping and population monitoring all other invertebrates combined, or indeed for schemes) are of shorter antiquity elsewhere but birds (1.2 m) (Thomas 2005). Despite a bur- it is clear that UK declines are typical of other geoning interest in UK moths that has seen 12.4 developed nations, and are exceeded by some million records amassed by over 5000 volunteer (Maes & Van Dyck 2001). In The Netherlands, recorders in recent years (BC’s Moths Count ini- for example, 24% of 71 butterfly species tiative) (see Chapter 8), butterflies are currently became extinct during the 20th century while (and regrettably) probably the only taxon of ter- the number of breeding birds increased by 20% restrial invertebrates across much of the world (Thomas 1995). for which it is realistic to assess the scale and There is some debate as to whether butterflies rates of change in species’ ranges or populations are indicators of change in other insects: Hambler (Lewis & Senior 2011). For the same reason, & Speight (2004) argued that butterflies have butterflies have been successfully used as char- suffered higher extinction rates than other ismatic flagships and umbrella species (see invertebrates according to UK RDBs; Thomas & Box 14.1) in insect conservation programmes Clarke (2004) attributed this discrepancy to an (New 1997; Thomas & Settele 2004; Fleishman artefactual underestimate of decline inherent in et al. 2005; Guiney & Oberhauser 2009). comparing poor with well-sampled taxa, and showed that butterflies experienced similar extinction rates to other groups when sampling Long-term change in populations intensity is factored in. Moreover, observed of Lepidoptera extinction rates in dragonflies, bumblebees and macro-moths have unequivocally been slightly higher than those of UK butterflies (Thomas Rates and causes 2005; Conrad et al. 2006). Whilst clearly unrep- resentative of certain species and functional Before discussing practical conservation of types, because of their popularity, ease of study Lepidoptera, it is necessary to consider their (e.g. conspicuous, day-active, often identifiable known rates and causes of change, and whether in the field) and patterns of species richness and these are representative of other insect species endemism that mirror those of many other (Thomas & Clarke 2004; Fleishman et al. 2005). insects, butterflies are increasingly used as indi- In the UK, which has the longest history of rig- cators of change in other taxa in Europe and to a orous recording, butterfly populations have lesser extent elsewhere. 0001738427.INDD 240 1/21/2013 3:38:55 PM A GLOBAL PERSPECTIVE ON CONSERVING BUTTERFLIES AND MOTHS AND THEIR HABITATS 241 Butterflies may be useful indicators of habitat able to remove more than a small proportion of change (Ricketts et al. 1999). We distinguish the effective breeding population of adult two types of indicator (Thomas et al. 2005): Lepidoptera per generation, because in most (i) the ’miners’ canary’ whose decline heralds studied species the majority of eggs are laid future losses for less sensitive species; and within 2–5 days of each female’s emergence, (ii) taxa which mirror change or predict the and for species with discrete generations, the presence (Fleishman et al. 2005) of poorly short-lived individuals emerge over a period of monitored organisms. Across Europe (Erhardt & 4–8 weeks. Thomas 1991; Thomas 2005), butterflies in Habitat loss, undoubtedly the prime culprit general are early warning systems for future (Stewart et al. 2007), can broadly be divided change in vertebrate (apart from mega-fauna) into two processes (Thomas 1991): (i) the and vascular plant populations. One family of destruction of primary and species-rich second- butterflies, the Lycaenidae, provides ultra- ary ecosystems by intensive modern agriculture, sensitive indicators of coming change in other exotic-species forestry, mining, armed conflict families, because many of them need two and illicit crops (Dávalos et al. 2011) and, to a specialized larval resources (foodplants, ants) lesser extent, urbanization; (ii) the reduced size, to co-occur (Thomas et al. 2005). We there- increased isolation and degradation in quality of fore advocate the application of standardized those fragments of potentially inhabitable bio- mapping and population monitoring schemes topes that survive. The first process effectively in nations where such schemes are absent, and eliminates all populations apart from pests of the monitoring of other arthropod taxa. crops and exploiters of ruderal plants. The second is less clear-cut but equally harmful, especially in developed regions (see below). Drivers of change Another driver of population reductions is climate change. Its observed impacts on Of the main drivers of global biodiversity loss, Lepidoptera are relatively minor so far but it is the spread of exotic pest species and direct over- predicted to rival habitat change (with which it exploitation by humans have had negligible interacts) in future decades (van Swaay et al. detectable impacts on populations of 2010a). Already in the Holarctic, non-migra- Lepidoptera (e.g. Collins & Morris 1985). So the tory species have shown southern or lowland banning of trade and collecting – the main contractions that exceed their northward or measure applied in many nations today and for altitudinal shifts in ranges (e.g. Parmesan et al. the first century of conservation practice in the 1999), whilst similar altitudinal shifts are UK – is inappropriate (unless coupled with detectable in moth communities in Borneo habitat conservation), because it fails to account (Chen et al. 2009). The net impacts on for the very different

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