Resident Butterflies Research Articles

A hydrogen isoscape for tracing the migration of herbivorous lepidopterans across the Afro-Palearctic range.

Many insect species undertake multigenerational migrations in the Afro-tropical and Palearctic ranges, and understanding their migratory connectivity remains challenging due to their small size, short life span and large population sizes. Hydrogen isotopes (δ2 H) can be used to reconstruct the movement of dispersing or migrating insects, but applying δ2 H for provenance requires a robust isotope baseline map (i.e. isoscape) for the Afro-Palearctic. We analyzed the δ2 H in the wings (δ2 Hwing ) of 142 resident butterflies from 56 sites across the Afro-Palearctic. The δ2 Hwing values were compared to the predicted local growing-season precipitation δ2 H values (δ2 HGSP ) using a linear regression model to develop an insect wing δ2 H isoscape. We used multivariate linear mixed models and high-resolution and time-specific remote sensing climate and environmental data to explore the controls of the residual δ2 Hwing variability. A strong linear relationship was found between δ2 Hwing and δ2 HGSP values (r2 = 0.53). The resulting isoscape showed strong patterns across the Palearctic but limited variation and high uncertainty for the Afro-tropics. Positive residuals of this relationship were correlated with dry conditions for the month preceding sampling whereas negative residuals were correlated with more wet days for the month preceding sampling. High intra-site δ2 Hwing variance was associated with lower relative humidity for the month preceding sampling and higher elevation. The δ2 Hwing isoscape is applicable for tracing herbivorous lepidopteran insects that migrate across the Afro-Palearctic range but has limited geolocation potential in the Afro-tropics. The spatial analysis of uncertainty using high-resolution climatic data demonstrated that many African regions with highly variable evaporation rates and relative humidity have δ2 Hwing values that are less related to δ2 HGSP values. Increasing geolocation precision will require new modeling approaches using more time-specific environmental data and/or independent geolocation tools.

Rewiring of interactions in a changing environment: nettle‐feeding butterflies and their parasitoids

Climate and land use change can alter the incidence and strength of biotic interactions, with important effects on the distribution, abundance and function of species. To assess the importance of these effects and their dynamics, studies quantifying how biotic interactions change in space and time are needed.We studied interactions between nettle‐feeding butterflies and their shared natural enemies (parasitoids) locally and across 500 km latitudinal gradient in Sweden. We also examined the potential impact of the range‐expansion of the butterfly Araschnia levana on resident butterflies via shared parasitoids, by studying how parasitism in resident butterflies covaries with the presence or absence of the newly‐established species. We collected 6777 larvae of four nettle‐feeding butterfly species (Aglais urticae, Aglais io, Ar. levana and Vanessa atalanta), over two years, at 19 sites distributed along the gradient. We documented the parasitoid complex for each butterfly species and measured their overlap, and analysed how parasitism rates were affected by butterfly species assemblage, variations in abundance, time, and the arrival of Ar. levana. Parasitoids caused high mortality, with substantial overlap in the complex of parasitoids associated with the four host butterflies. Levels of parasitism differed significantly among butterflies and were influenced by the local butterfly species assemblage. Our results also suggest that parasitism in resident butterflies is elevated at sites where Ar. levana has been established for a longer period.In our study system, variations in butterfly species assemblages were associated in a predictable way with substantial variations in rates of parasitism. This relationship is likely to affect the dynamics of the butterfly host species, and potentially cascade to the larger number of species with which they interact. These results highlight the importance of indirect interactions and their potential to reorganise ecological communities, especially in the context of shifts in species distributions in a warmer world.

Flower-Visiting Butterflies Avoid Predatory Stimuli and Larger Resident Butterflies: Testing in a Butterfly Pavilion.

The flower-visiting behaviors of pollinator species are affected not only by flower traits but also by cues of predators and resident pollinators. There is extensive research into the effects of predator cues and resident pollinators on the flower-visiting behaviors of bee pollinators. However, there is relatively little research into their effects on butterfly pollinators probably because of the difficulty in observing a large number of butterfly pollination events. We conducted a dual choice experiment using artificial flowers under semi-natural conditions in the butterfly pavilion at Tama Zoological Park to examine the effects of the presence of a dead mantis and resident butterflies have on the flower-visiting behavior of several butterfly species. From 173 hours of recorded video, we observed 3235 visitations by 16 butterfly species. Statistical analysis showed that (1) butterflies avoided visiting flowers occupied by a dead mantis, (2) butterflies avoided resident butterflies that were larger than the visitor, and (3) butterflies showed greater avoidance of a predator when the predator was present together with the resident butterfly than when the predator was located on the opposite flower of the resident. Finally, we discuss the similarities and differences in behavioral responses of butterfly pollinators and bees.

Contrasting the distribution of butterflies and termites in plantations and tropical forests

In the tropics vast areas of natural forests are being converted into plantations. The magnitude of the resulting loss in arthropod biodiversity and associated ecosystem services represents a significant topic of research. In this study we contrasted the abundance, species richness and faunal turnover of butterflies, resident butterflies (i.e., whose host plants were ascertained to occur in the habitats studied) and termites between small (average 4.3 ha) 20+ year old exotic plantations (teak and Terminalia), native plantations (Cedro espino), and an old growth forest in Panama. We used Pollard walks and manual search to quantify the abundance or occurrence of butterflies and termites, respectively. In 2014 we observed 4610 butterflies representing 266 species and 108 termite encounters (out of 160 quadrats) representing 15 species. Butterflies were more abundant and diverse in plantations than in the forest, whereas this pattern was opposite for resident butterflies and termites. There was marked faunal turnover between plantations and forest. We conclude that (a) the magnitude of faunal changes between forest and plantations is less drastic for termites than for butterflies; (b) resident butterfly species are more impacted by the conversion of forest to plantations than all butterflies, including transient species; and (c) species richness does not necessarily decrease in the series forest > native > exotic plantations. Whereas there are advantages of studying more tractable taxa such as butterflies, the responses of such taxa can be highly unrepresentative of other invertebrate groups responsible for different ecological services.

Species range expansion constrains the ecological niches of resident butterflies

AbstractAimChanges in community composition resulting from environmental changes modify biotic interactions and affect the distribution and density of local populations. Such changes are currently occurring in nettle‐feeding butterflies in Sweden where Araschnia levana has recently expanded its range northward and is now likely to interact with resident species (Aglais urticae and Aglais io). Butterfly occurrence data collected over years and across regions enabled us to investigate how a recent range expansion of A. levana may have affected the environmental niche of resident species.LocationWe focused on two regions of Sweden (Skåne and Norrström) where A. levana has and has not established and two time periods (2001–2006 and 2009–2012) during its establishment in Skåne.MethodsWe performed two distinct analyses in each region using the PCA‐env and the framework described in Broennimann et al. (2012). First, we described the main sources of variation in the environment. Second, in each time period and region, we characterized the realized niches of our focal species across topographic and land use gradients. Third, we quantified overlaps and differences in realized niches between and within species over time.ResultsIn Skåne, A. levana has stabilized its distribution over time, while the distribution of the native species has shifted. These shifts depicted a consistent pattern of avoiding overlap between the native species and the environmental space occupied by A. levana, and it was stronger for A. urticae than for A. io. In both regions, we also found evidence of niche partitioning between native species.Main conclusionsInterspecific interactions are likely to affect local species distributions. It appears that the ongoing establishment of A. levana has modified local biotic interactions and induced shifts in resident species distributions. Among the mechanisms that can explain such patterns of niche partitioning, parasitoid‐driven apparent competition may play an important role in this community.

Hairstreaks (and Other Insects) Feeding at Galls, Honeydew, Extrafloral Nectaries, Sugar Bait, Cars, and Other Routine Substrates

The northern oak hairstreak ( Satyrium favonius ontario (W. H. Edwards)) is one of the most infrequently encountered resident butterflies in New England; only three adults were seen over the five-year course of the Connecticut Butterfly Atlas project (O'Don-nell et al. 2007). Shapiro (1974) considered it one of the rarest northeastern butterflies, and (as often quoted elsewhere in the butterfly literature) Holland (1931) regarded the northern oak hairstreak to be so infrequent that he wondered if the butterfly might be a re-occurring aberration of a more common hairstreak. Its scarcity is mysterious in that its host, oak, is one of the most abundant plant genera in the East. Its congener, the striped hairstreak ( Satyrium liparops (Le Conte)) is infrequently encountered in New England; most reports are of adults nectaring at milkweed blossoms in late June and July. However, its late instars are among the most common lepidopteran larvae on apple and highbush blueberry ( Vaccinium corymbosum L.) in early June. In spring 2013, we found numerous striped hairstreak larvae while beating blueberry for immatures of Henry's elfin butterfly ( Callophrys henrici (Grote & Robinson)); five to eight S. liparops caterpillars were found on every highbush blueberry that was sampled along a woodland path in Salem, Connecticut. The same path and adjacent yard yielded only two striped hairstreak adult sightings over the course of the next six weeks despite repeated and …

Diversity and Abundance of Butterfly Species in the Abiriw and Odumante Sacred Groves in the Eastern Region of Ghana

Sacred groves in Ghana have been adopted as one of the strategies to mitigate the loss of biodiversity. They are seriously under threat from anthropogenic activities. A six month survey of the butterfly fauna in the Abiriw and Odu mante sacred groves in the Akwapim North and South Districts, respectively of the Eastern Region of Ghana was conducted to characterize resident butterfly species diversity and abundance. The transect count method and charaxes traps were used to sample the butterflies. Analysis of butterfly diversity in these groves, which range in size fro m 400 m 2 to 250 m 2 , was used to evaluate their effectiveness in achieving conservation objectives. Co mmun ity diversity was characterized in terms of, (a) number of species accumulated versus sampling effort, (b) nonparametric richness estimates, (c) Simpson's and Shannon-Weiner Indices of Diversity, and (d) Co mplementarity of co mmunit ies. A total of 1169 ind ividual butterflies were trapped across all sites representing 89 species from 10 families. Butterfly species richness and evenness in the Abiriw g rove was higher than that of the Odumante grove, however, the Abiriw grove harboured a resident community that was not distinctive from the Odu mante grove. These findings add to the body of knowledge that indicates that large groves are the foundation of successful conservation programs. Nonetheless, it was observed that both groves harbour a number of species that appear vulnerable to dynamics of fo rest frag mentation based on changes in their relative abundance across sites. The findings are discussed in the context of potential indicator species and theoretical predictions of at-risk species.

Long‐term land‐use changes and extinction of specialised butterflies

Abstract. 1 Land-use change in 450 ha in southern Sweden between 1814 and 2004 was recorded. Butterflies and burnet moths were surveyed in 1904–1913 and 2001–2005. 2 We explore if local extinctions were related to land-use changes and species attributes. 3 Land use changed drastically over the 190-year period, and the largest relative change occurred for hay meadows with late harvest, which decreased from 28% to 0%. The area changed from grasslands and grazed forests to being dominated by timber forests. Previous open grazed mixed woodlands changed to spruce plantations with clear-cuts. 4 Of the 48 resident butterfly and burnet moths found a century ago, 44% have become extinct. The extinct Aporia cratægi, Colias palaeno, and Leptidea sinapis were abundant 100 years ago and had their highest densities in flower-rich glades in forest, a habitat which no longer exists. 5 The butterfly extinctions could be predicted from species-specific attributes as a short flight length period (P < 0.02), narrow habitat breadth (P < 0.02), small distribution area in Europe (P = 0.033) and possibly larvae food plant nitrogen class (P < 0.06). In a multiple logistic regression, the flight length period was the only significant variable because the independent variables were intercorrelated. 6 We conclude that the most important factor explaining the high extinction rate is that flower-rich habitats have disappeared from both woodlands as well as from open farmlands. The most sensitive species are specialised species with a short summer flight which have gone extinct. Only the most unspecialised species still persist in the current landscape.

LOW-QUALITY HABITAT CORRIDORS AS MOVEMENT CONDUITS FOR TWO BUTTERFLY SPECIES

Corridors are a primary conservation tool to increase connectivity, promote individual movement, and increase gene flow among populations in fragmented landscapes. The establishment of effective conservation corridors will depend on constructing or preserving connecting habitat that attracts dispersing individuals. Yet, it remains unclear whether corridors must necessarily be composed of high-quality habitat to be effective and promote dispersal and gene flow. We address this issue with two mobile, open-habitat butterfly species, Junonia coenia Hübner and Euptoieta claudia Cramer. Using experimental landscapes created explicitly to examine the effects of corridors on dispersal rates, we show that open-habitat corridors can serve as dispersal conduits even when corridors do not support resident butterfly populations. Both butterfly species were rare near forest edges and equally rare in narrow corridors, yet both species dispersed more often between patches connected by these corridors than between isolated patches. At least for species that can traverse corridors within a generation, corridor habitat may be lower in quality than larger patches and still increase dispersal and gene flow. For these species, abundance surveys may not accurately represent the conservation value of corridors.

Comparative influence of spatial scale on beta diversity within regional assemblages of birds and butterflies

AbstractAim We examined whether variation in species composition of breeding birds and resident butterflies in the Great Basin of North America depended on sampling grain (the smallest resolvable unit of study) and on the relative proximity of sampling units across the landscape. We also compared patterns between the two taxonomic groups with reference to their life‐history characteristics.Location Data for our analyses were collected from 1996 to 2003 in three adjacent mountain ranges in the central Great Basin (Lander and Nye counties, Nevada, USA): the Shoshone Mountains, Toiyabe Range and Toquima Range.Methods Data on species composition for both taxonomic groups were collecting using standard inventory methods for birds and butterflies in temperate regions. Data were compiled at three sampling grains, sites (average 12 ha), canyons (average 74 ha) and mountain ranges. For each sampling grain in turn, we calculated similarity of species composition using the Jaccard index. First, we investigated whether mean similarity of species composition among the three ranges differed as a function of the grain size at which data were compiled. Secondly, we explored whether mean similarity of species composition was greater for canyons within the same mountain range than for canyons within different mountain ranges. Thirdly, we examined whether mean similarity of species composition at the site level was different for sites within the same canyon, sites within different canyons in the same mountain range, and sites within canyons in different mountain ranges. We used a Bayesian model to analyse these comparisons.Results For both taxonomic groups, mean similarity of species composition increased as the sampling grain increased. The effect of spatial grain was somewhat greater for birds than for butterflies, especially when the intermediate sampling grain was compared with the smallest sampling grain. Similarity of species composition of butterflies at each sampling grain was greater than similarity of species composition of birds at the same grain. Mean similarity of species composition of both birds and butterflies at the canyon level and site level was affected by relative proximity of sampling locations; beta diversity increased as the relative isolation of sampling locations increased.Main conclusions The sensitivity of beta diversity to sampling grain likely reflects the effect of local environmental heterogeneity: as sampling grain increases, biotic assemblages appear more homogeneous. Although breeding birds in our study system have larger home ranges than resident butterflies, birds may have more specialized resource requirements related to vegetation structure and composition, especially at small sampling scales. The degree of variation in species composition of both taxonomic groups suggests that spatially extensive sampling will be more effective for drawing inferences about regional patterns of species diversity than intensive sampling at relatively few, smaller sites.

Does Müllerian Mimicry Work in Nature? Experiments with Butterflies and Birds (Tyrannidae)1

ABSTRACTThe selective advantage of Müllerian mimicry in nature was investigated by releasing live mimetic and nonmimetic butterflies close to wild, aerial‐hunting tropical kingbirds (Tyrannus melancholicus) and cliff‐flycatchers (Hirundinea ferruginea) in three Amazon habitats (rain forest, a city, and “canga” vegetation). Only mimetic butterflies elicited sight‐rejections by birds, but protection conferred by mimicry was restricted to sites in which both predators and mimics co‐occurred, as in the case of six mimicry rings at a forest site and two at a city site. Most other Müllerian mimics released at city and canga vegetation were heavily attacked and consumed by birds. These results appear to reflect the birds’previous experiences with resident butterfly faunas and illustrate how birds’discriminatory behavior varied among habitats that differed in butterfly species and mimicry ring composition.

Validation Tests of Predictive Models of Butterfly Occurrence Based on Environmental Variables

Abstract: Ecologists often seek to predict species distributions as functions of abiotic environmental variables. Statistical models are useful for making predictions about the occurrence of species based on variables derived from remote sensing or geographic information systems. We previously used 14 topographically based environmental variables from 49 locations in the Toquima Range ( Nevada, U.S.A. ) and species inventories conducted over 4 years ( 1996–1999 ) to model logistically the occurrence of resident butterfly species. To test the models, we collected new validation data in 39 locations in the nearby Shoshone Mountains in 2000–2001. We used a series of “classification rules” based on conventional logistic and Bayesian criteria to assess the success rates of predictions. The classification rules represented a gradient of stringency in the “certainty” with which predictions were made. More stringent rules reduced the number of predictions made but greatly increased the success rate of predictions. For comparisons of classification rules making similar numbers of predictions, conventional logistic and Bayesian criteria produced similar outcomes. Success rates for predicted absences were uniformly higher than for predicted presences. Increasing the temporal extent of data from 1 to 2 years elevated success rates for predicted presences but decreased success rates for predicted absences, leaving the overall success rates essentially the same. Although species occurrence rates ( the proportion of locations in which each species was found ) were correlated between the modeling and validation data sets, occurrence rates for many species increased or decreased substantially; erroneous predictions were more likely for those taxa. Model fit ( measured by the explained deviance ) was an indicator of the probable success rate of predicted presences but not of predicted absences or overall success rates. We suggest that classification rules for predicting likely presences and absences may be decoupled to improve overall predictive success. Our general framework for modeling species occurrence is applicable to virtually any taxonomic group or ecosystem.

Twilight fighting in the evening brown butterfly, Melanitis leda (L.) (Nymphalidae): age and residency effects

Butterflies are conspicuous among animals that fight for mating opportunities because it is not clear how contest costs could accrue. Nevertheless, the bulk of research in this group suggests that contests are settled on the basis of asymmetries in fighting ability (the superior competitor hypothesis). There is also a consistent effect on contest escalation due to apparent 'confusion' over residency, which could result from resident butterflies playing different tactics than non-residents, or from a causal link between residency and fighting ability. I addressed these hypotheses by studying contest behavior in the crepuscular species Melanitis leda (L.) (Nymphalidae) over a 5-month period in tropical Australia. Males competed via conspicuous two-stage maneuvers of a form unique among butterflies. Prior residents won 77% of all contests. Non-resident males arrived and perched in occupied sites until challenged by incumbent residents, and the aggressiveness of these interlopers increased as a function of the time before they were detected. Contest winners also tended to be younger than losers, and contest escalation was negatively related to both the age of the losing male and the magnitude of the between-combatant age asymmetry. These results are consistent with the superior competitor hypothesis based upon age as a determinant (or correlate) of fighting ability, but also suggest residency has a unique influence on contest behavior. Further research is clearly required to unravel the effects of age, residency and other potential biophysical determinants of fighting ability in this species.

Does Müllerian Mimicry Work in Nature? Experiments with Butterflies and Birds (Tyrannidae)1

The selective advantage of Müllerian mimicry in nature was investigated by releasing live mimetic and nonmimetic butterflies close to wild, aerial-hunting tropical kingbirds (Tyrannus melancholicus) and cliff-flycatchers (Hirundinea ferruginea) in three Amazon habitats (rain forest, a city, and “canga” vegetation). Only mimetic butterflies elicited sight-rejections by birds, but protection conferred by mimicry was restricted to sites in which both predators and mimics co-occurred, as in the case of six mimicry rings at a forest site and two at a city site. Most other Müllerian mimics released at city and canga vegetation were heavily attacked and consumed by birds. These results appear to reflect the birds' previous experiences with resident butterfly faunas and illustrate how birds' discriminatory behavior varied among habitats that differed in butterfly species and mimicry ring composition.

Modelling butterfly species richness using mesoscale environmental variables: model construction and validation for mountain ranges in the Great Basin of western North America

If species richness can be modelled as a function of easily quantified environmental variables, the scientific foundation for land-use planning will be strengthened. We used Poisson regression to develop a predictive model of species richness of resident butterflies in the central Great Basin of western North America. Species inventory data and values for 14 environmental variables from 49 locations (canyon segments) in the Toquima Range (Nevada, USA) were used to build the model. We also included squares of the environmental variables to accommodate potential non-linear relationships. Species richness of butterflies was a significant function of elevation and local topographic heterogeneity, with the selected model explaining 57% of the total deviance of species richness. Predictive variables can be derived efficiently from GIS-based data for areas in which species inventories have not yet been conducted. Therefore, in addition to evaluating the ability of the model to explain observed variation in species richness, we generated and tested predictions of species richness for ‘new’ locations that had not been used to build the model. Predictions were effective for five new segments also located in the Toquima Range, but not for 22 new segments in the nearby Shoshone Range. We discuss issues related to generalizability and data quality in model development.

Topographic Determinants of Faunal Nestedness in Great Basin Butterfly Assemblages: Applications to Conservation Planning

Abstract: We examined factors possibly responsible for a nested distributional pattern of resident butterflies in the Toquima Range, a mountain range in the Great Basin of western North America. In related analyses, Poisson‐based modeling indicated that species richness is better explained as a function of elevation and local topographic heterogeneity than by area per se. Therefore, we explored whether area, elevation, and topographic heterogeneity affected relative degree of nestedness. Elevation and topographic heterogeneity not only explained a significant percentage of the total deviance in species richness but also may be responsible for generating nested species distributions. The species‐presence matrix ordered by the elevation‐heterogeneity model was significantly more nested than the matrix ordered by area. The matrix ordered by the elevation‐heterogeneity model also was significantly more nested than matrices ordered by three other environmental variables that did not explain significant variance in species richness, indicating that the model is unlikely to be an artifact. The influence of area on distribution patterns may be relatively slight because it was not significantly correlated with species richness or topographic heterogeneity in this system. Elevation covaried with both species richness and area, but the former correlation was positive and the latter was negative. Our results suggest that faunal richness and compositional patterns are related to independent variables that can be measured extensively—through satellite or airborne telemetry—thus reducing dependence on labor‐intensive measurements of habitat. Because nestedness analyses may help reveal causes, or at least correlates, of species composition, we believe they are a promising tool for conservation planning.

Modeling and Predicting Species Occurrence Using Broad‐Scale Environmental Variables: an Example with Butterflies of the Great Basin

Abstract:If occurrence of individual species can be modeled as a function of easily quantified environmental variables (e.g., derived from a geographic information system [GIS]) and the predictions of these models are demonstrably successful, then the scientific foundation for management planning will be strengthened. We used Bayesian logistic regression to develop predictive models for resident butterflies in the central Great Basin of western North America. Species inventory data and values for 14 environmental variables from 49 locations (segments of canyons) in the Toquima Range ( Nevada, U.S.A.) were used to build the models. Squares of the environmental variables were also used to accommodate possibly nonmonotonic responses. We obtained statistically significant models for 36 of 56 (64%) resident species of butterflies. The models explained 8–72% of the deviance in occurrence of those species. Each of the independent variables was significant in at least one model, and squared versions of five variables contributed to models. Elevation was included in more than half of the models. Models included one to four variables; only one variable was significant in about half the models. We conducted preliminary tests of two of our models by using an existing set of data on the occurrence of butterflies in the neighboring Toiyabe Range. We compared conventional logistic classification with posterior probability distributions derived from Bayesian modeling. For the latter, we restricted our predictions to locations with a high ( 70%) probability of predicted presence or absence. We will perform further tests after conducting inventories at new locations in the Toquima Range and nearby Shoshone Mountains, for which we have computed environmental variables by using remotely acquired topographic data, digital‐terrain and microclimatic models, and GIS computation.

Patterns and processes of nestedness in a Great Basin butterfly community.

We examined nestedness and potential mechanisms causing that distributional pattern in resident butterfly communities of the Toiyabe Range, a mountain range in the central Great Basin of western North America. We tested whether life history characteristics, including habitat use and vagility, affected the relative degree of nestedness or mean species incidence. We also tested whether nestedness at the level of individual species was independent of life history. Relationships between distributional patterns and habitat use, particularly in ecologically sensitive riparian areas, are relevant to ongoing conservation planning in the Great Basin. The distributional pattern of the 68 resident butterfly species in 19 Toiyabe Range canyons was significantly nested, as was the distribution of all functional subgroups that we tested. Life history affected neither relative nestedness of species groups nor mean species incidence. More than 80% of the individual butterfly species that inhabit the Toiyabe Range had distributions that were more nested than expected. Colonization does not appear to have played an important role in determining the composition of butterfly communities in Toiyabe Range canyons. Likewise, selective dispersal has probably played a minor role in producing nested distributions of Toiyabe Range butterflies. Our results suggest either that impacts to riparian areas are not jeopardizing species viability, or that highly sensitive butterfly species have already been extirpated from the Toiyabe Range.

Coincidence in the distributions of butterflies and their foodplants

The relationship between the geographic distribution of consumers and of their hosts (foodplants) is examined using the resident butterfly fauna of Britain. On average, butterfly species that feed on more widely distributed hosts are themselves more widely distributed. However, the relationship is approximately triangular and the upper constraint imposed by the range sizes of hosts is not closely followed; some species have much more restricted ranges than their hosts have. There is no relationship between the proportion of the range of the foodplant that is occupied and the size of the range of the foodplant. Monopbagous butterfly species have smaller range sizes than polyphagous species, probably as a consequence of the greater potential range sizes of the latter. Those plant species that are used as hosts by butterflies have larger range sizes than expected by chance, and individual polyphagous butterfly species tend disproportionately to be found in areas containing larger numbers of their host plant species. In sum, this study reveals a complex relationship between the distribution of butterflies and that of their resources (foodplants).

Territorial defence in speckled wood butterflies: do the hottest males always win?

Males of the butterflyPararge aegeriadefend sun spot territories on the forest floor as a strategy to locate females: the defence involves a spiral flight between two competing males. The success of any particular fight has been interpreted as following the simple rule ‘resident wins, intruder loses’ as predicted by game theory models. Here we use field experiments to show that temperature has a marked effect on the territorial defence of these ectothermic insects. The spiral flights were true contests, not conventional signals, so the flight endurance of the butterflies was an important factor in determining the result of the contest. Butterflies that were warmer could fly for longer and were more likely to win a contest; therefore temperature was an important component of contest asymmetry, and resident butterflies that increased their body temperatures by basking in sun spots were more likely to win than the intruding males which might have cooled down during flight around the site. The rule that the resident always wins is not disputed; however, the causal factors underpinning the rule are questioned.