Interrelations Among Habitat Use, Behavior, and Flight-Related Morphology in Two Cooccurring Satyrine Butterflies, Maniola jurtina and Pyronia tithonus

Mobility, activity patterns, habitat use, and some morphological traits of two often cooccurring satyrine butterflies of grasslands—the meadow brown (Maniola jurtina) and the hedge brown (Pyronia tithonus)—were studied by a mark-release-recapture method at two sites. Additionally, someflight-related morphological traits of a series of collected females of P. tithonus were compared between recently colonized and permanent populations. The more active, but less mobile P. tithonus got faster wing damage than did M. jurtina and had more, and more symmetrically spread eyespots onthe wings. For both species, the microdistribution was affected by shelter, long vegetation, and nectar, but this was more pronounced in P. tithonus. It is hypothesized that P. tithonus may traverse the same landscape at a slower rate than M. jurtina.     

Agri-environment schemes and butterflies: the utilisation of 6 m grass margins

The utilisation of 6 m countryside stewardship scheme (CSS) grass margins by butterflies was studied at two farms in Essex between 1997 and 2000. The aim of the study was to establish whether grass margins in cereal fields, as set up and managed under CSS guidelines, would be beneficial to common farmland butterflies. Eight 6 m grass margins (total length 3492 m) and two control sections (no margin; total length 700 m) were monitored over the first years of the agreements using the transect method. Significantly greater total numbers of butterflies and individuals of Maniola jurtina were seen on the 6 m grass margins than on the control sections. There was a significant increase in abundance of Maniola jurtina on the margins over the 4-year study period. Significantly more butterflies and Maniola jurtina were seen on the sown 6 m grass margin next to set-aside than on any of the other methods of establishment. Sown next to set-aside was best for Pyronia tithonus, but not significant.     

Support for mending the matrix: resource seeking by butterflies in apparent non-resource zones

In conserving organisms, a bipolar view has generally been adopted of landscapes, in which resources are allocated to patches of habitats and the matrix ignored. Allocating additional resources to the matrix would depend on two conditions: first, that organisms search for resources in landscapes regardless of differences in vegetation types and resource availability; second, that when resources occur in the matrix they are used by species. Behavioural data linked to biotope and substrate types, on three pierid species (Pieris brassicae, P. rapae, P. napi), have been examined to explore the relationship between flight modes and resource availability. Search flight and resource use, taken as measures of resource quests, occur extensively in all biotopes and over all substrates in addition to direct linear flight, more typical of butterflies when migrating between habitat units. Resource seeking and using even exceed direct flight in some biotopes that have been regarded generally as lacking in resources for these butterflies. For example, such is the case for P. brassicae in woodland and for P. rapae in scrub. This finding supports the view for repairing the matrix and enhancing the general countryside outside habitat patches with resources increasingly being made for organisms. The proviso is that species’ requirements are adequately researched and resourced so as not to become sinks.     

Butterfly Density and Behaviour in Uncut Hay Meadow Strips: Behavioural Ecological Consequences of an Agri-Environmental Scheme

Sparing zones from mowing has been proposed, and applied, to improve local conditions for survival and reproduction of insects in hay meadows. However, little is known about the efficiency of refuge zones and the consequences for local populations. We studied population densities of butterflies before and after mowing in the refuge zone of 15 meadows in 2009 and 2011. We also studied the behaviour of the meadow brown (Maniola jurtina) comparing nectar use, interactions and flights in the refuge zone before and after mowing. Densities of grassland butterflies in this zone doubled on average after mowing. The density of females of M. jurtina increased on average fourfold, while males showed a more modest increase. In line with the idea of increased scramble competition in the refuge zone after mowing, M. jurtina increased the time spent on nectar feeding, the preferred nectar source was visited more frequently, and females made more use of non-preferred nectar sources. Maniola jurtina did not interact more with conspecifics after mowing, but interactions lasted longer. Flight tracks did not change in linearity, but were faster and shorter after mowing. After mowing, only a part of the local grassland butterflies moved to the uncut refuge zone. The resulting concentration effect alters the time allocated to different activities, nectar use and movements. These aspects have been largely ignored for agri-environmental schemes and grassland management in nature reserves and raise questions about optimal quantities and quality of uncut refuge sites for efficient conservation of grassland arthropods in agricultural landscapes.     

Dispersal behaviour of individuals in metapopulations of two British butterflies

Dispersal patterns are important in metapopulation ecology because they affect the dynamics and survival of populations. However, because little empirical information exists on dispersal behaviour of individuals, theoretical models usually assume random dispersal. Recent empirical evidence, by contrast, suggests that the butterfly Maniola jurtina uses a non‐random, systematic dispersal strategy, can detect and orient towards habitat from distances of 100–150 m, and prefers a familiar habitat patch over a non‐familiar one (‘homing behaviour’). The present study (1) investigated whether these results generalise to another butterfly species, Pyronia tithonus; and (2) examined the cause of the observed ‘homing behaviour’ in M. jurtina. P. tithonus used a similar non‐random, systematic dispersal strategy to M. jurtina, had a similar perceptual range for habitat detection and preferred a familiar habitat patch over a non‐familiar one. The ‘homing behaviour’ of M. jurtina was found to be context‐dependent: individual M. jurtina translocated within habitat did not return towards their capture point, whereas individuals translocated similar distances out of habitat did return to their ‘home’ patch. We conclude that butterfly ‘homing behaviour’ is not based on an inherent preference for a familiar location, but that familiarity with an area facilitates the recognition of suitable habitat, towards which individuals orient if they find themselves in unsuitable habitat. Contrary to conventional wisdom, we suggest that frequent, short ‘excursions’ over habitat patch boundaries are evolutionarily advantageous to individuals, because increased familiarity with the surrounding environment is likely to increase the ability of a straying animal to return to its natural habitat, and to reduce the rate of mortality experienced by individuals attempting to disperse between habitat patches. We discuss the implications of the non‐random dispersal for existing metapopulation models, including models of the evolution of dispersal rates.     

Biotope Use and Trends of European Butterflies

Europe has undergone substantial biotope loss and change over the last century and data are needed urgently on the rate of decline in different wildlife groups in order to identify and target conservation measures. However, pan-European data are available for very few taxonomic groups, notably birds. We present here the first overview of trends for an insect group within different biotopes across Europe, based on data from the Red Data Book of European Butterflies. The most important biotopes for Europe’s 576 butterfly species, including threatened species, are man-made or man-influenced, notably types of grassland or heath/scrub communities. Our results show that butterflies are declining substantially across Europe, with a decline in distribution of −11% over the last 25 years. The distributions of the 25 most “generalist” species are declining only slowly (−1%) compared to specialist butterflies of grassland (−19%), wetlands (−15%), and forests (−14%). On average, grassland butterflies have declined somewhat slower than farmland birds (annual decrease −0.8% compared to −1.5%), but woodland butterflies have decreased more rapidly (−0.01% to −0.6%) than woodland birds, which are more or less stable. The sensitivity of butterflies to environmental changes and the availability of data across Europe suggest that they are very good candidates to build biodiversity indicators and, along with other major groups such as birds, suitable to monitor progress towards the EU target of halting biodiversity loss by 2010. An erratum to this article is available at .     

Mechanical determinants of nectar-feeding energetics in butterflies: muscle mechanics,feeding geometry,and functional equivalence

Summary We develop a mechanistic model for nectar feeding in butterflies that integrates the two basic components of the feeding process: the fluid dynamics of nectar flow through the food canal and the contractile mechanics of the muscular, cibarial pump. We use the model to predict the relation between rate of energy intake during feeding and nectar concentration. We then identify nectar concentations that maximize energy intake rates (the optimal concentrations). We illustrate the model using measurements of the food canal and cibarium of Pieris butterflies. The model predicts an overall optimal range of nectar concentration of 31–39% sucrose for butterflies, which is in agreement with previously reported laboratory values. The model also predicts an interaction among the geometries of the food canal, the cibarial cavity, and the cibarial muscles, that allows us to identify the combinations of food canal, cibarium, and muscle dimensions that yield the highest rates of energy intake. Nectar-feeding is functionally equivalent in butterflies and hummingbirds: two physically different feeding mechanisms can yield identical energy intake rates. This equivalence results from a mathematical and physical similarity between quasi-steady-state fluid flow in hummingbrid tongues and the force-velocity characteristics of contracting cibarial muscle in butterflies.     

Effect of local weather on butterfly flight behaviour,movement, and colonization: significance for dispersal under climate change

Recent climate change is recognized as a main cause of shifts in geographical distributions of species. The impacts of climate change may be aggravated by habitat fragmentation, causing regional or large scale extinctions. However, we propose that climate change also may diminish the effects of fragmentation by enhancing flight behaviour and dispersal of ectothermic species like butterflies. We show that under weather conditions associated with anticipated climate change, behavioural components of dispersal of butterflies are enhanced, and colonization frequencies increase. In a field study, we recorded flight behaviour and mobility of four butterfly species: two habitat generalists (Coenonympha pamphilus; Maniola jurtina) and two specialists (Melitaea athalia; Plebejus argus), under different weather conditions. Flying bout duration generally increased with temperature and decreased with cloudiness. Proportion of time spent flying decreased with cloudiness. Net displacement generally increased with temperature. When butterflies fly longer, start flying more readily and fly over longer distances, we expect dispersal propensity to increase. Monitoring data showed that colonization frequencies moreover increased with temperature and radiation and decreased with cloudiness. Increased dispersal propensity at local scale might therefore lower the impact of habitat fragmentation on the distribution at a regional scale. Synergetic effects of climate change and habitat fragmentation on population dynamics and species distributions might therefore appear to be more complex than previously assumed.     

Agri-environment schemes and butterflies: the utilisation of two metre arable field margins

The utilisation of two metre field margins by butterflies was studied at three farms in Essex, south east England between 1997 and 2000. The aim of the study was to establish whether field margins, as set up and managed under Countryside Stewardship Scheme guidelines, were beneficial to common farmland butterflies. Thirteen two metre margins (total length 4478 m) and three sections with no margin (total length 656 m) were monitored over the 4 year period using the transect method. Significantly more Maniola jurtina, Thymelicus sylvestris and Thymelicus lineola were seen on the two metre margins than on the control sections, but there was a significant reduction in abundance of Thymelicus sylvestris, Thymelicus lineola and Ochlodes venata on the margins over the 4 year study period. Only the abundance of Pyronia tithonus increased significantly on the two metre margins over that period.     

Seasonal changes in a honeyeater assemblage in Banksia woodland near Perth,Western Australia

Abstract

Honeyeaters were the most numerous birds in banksia woodland near Perth, Western Australia, throughout the year. Numbers were greatest in a Banksia littoralis swamp, but only during those few months when it contained large amounts of nectar. In the surrounding woodland, numbers were lower but fairly constant during the year. This reflects the smaller amounts of nectar produced throughout the year, by the overlapping flowering patterns of several Banksia and Adenanthos species.

Large and medium-sized honeyeaters (wattlebirds and New Holland Honeyeaters) and flocking silvereyes dominated the swamp when it flowered. In contrast, small honeyeaters (spinebills and Brown Honeyeaters), many of whom were highly territorial residents, comprised the majority of the woodland assemblage throughout the year. These observations support a model based upon aggressive defence of rich nectar sources by the larger honeyeater species, and more efficient exploitation of dispersed flowers by smaller honeyeaters.     

Preference of cabbage white butterflies and honey bees for nectar that contains amino acids

Summary Amino acids occur in most floral nectars but their role in pollinator attraction is relatively unstudied. Nectars of butterfly-pollinated flower tend to have higher concentrations of amino acids than do flowers pollinated by bees and many other animals, suggesting that amino acids are important attractants of butterflies to flowers. In order to determine whether amino acids are important in attracting butterflies and bees, we tested the preference of cabbage white butterflies (Pieris rapae) and honey bees (Apis mellifera) by allowing them to feed from artificial flowers containing sugar-only or sugar-amino acid mimics ofLantana camara nectar. Honey bees and female cabbage white butterflies consumed more sugar-amino acid nectar than sugar-only nectar. In addition, female cabbage white butterflies visited artificial flowers containing sugar-amino acid nectars more frequently than flowers containing sugar-only nectars; honey bees spent more time consuming the sugar-amino acid nectar. Male cabbage white butterflies did not discriminate between the two nectars. These results support the hypothesis that the amino acids of nectar contribute to pollinator attraction and/or feeding.     

Relationship of butterfly diversity with nectar plant species richness in and around the Aokigahara primary woodland of Mount Fuji,central Japan

We examined the relationships between the diversities of vegetation, adult nectar plants, and butterflies in and around the Aokigahara primary woodland on the northwestern footslopes of Mount Fuji, central Japan. The results showed that the nectar resource utilization by adult butterflies was significantly biased to herbaceous plants, especially to perennials, compared to woody species, although most of the study area was in and near a primary woodland. There were greater nectar plant species in sites with greater plant species richness. Among the butterfly community indices analyzed, the strongest correlation was detected between butterfly species richness and nectar plant species richness at each site. Another close correlation was detected between the species richness of nectar plants and herbaceous plants at each site. These results suggest that herbaceous plant species richness in a habitat plays a central role in its nectar plant species richness, and the nectar plant richness is a highly important factor supporting its adult butterfly species richness. Consequently, we propose that the maintenance and management of herbaceous plant species richness in a butterfly habitat, which lead to those of its nectar plant species richness, are very important for conservation of butterfly diversity even in and around woodland landscapes of temperate regions.     

蝴蝶在生境和生物小区之间的移位伴随着对外来蜜源的利用

在发育成熟的温带环境中,植食性昆虫群落能迅速适应引入植物并将其作为幼虫的食物和花蜜.我们研究了经过森林砍伐的热带环境中蝴蝶对利用引入植物作为蜜源植物的适应快慢程度,并研究了蝴蝶-显花植物在新的生物小区中出现的范围,发现蝴蝶对引入显花植物的利用和探访多于本地植物,这与引入植物在调查地点、生物小区和植物丰度中的普遍性有关.此外,取食花蜜的蝴蝶和显花植物与正在形成的的生物小区有关,例如路边、农田、集约耕地以及花园.在这些新生物小区中,引入植物很重要,因为它们为蝴蝶提供了蜜源.     

Pollen amino acids—an additional diet for a nectar feeding butterfly?

The increase of the amino acid concentration over different time intervals in artificial nectar (i.e., a sucrose solution) due to pollen contamination was investigated in four Californian plant species (Aesculus californica, Amsinckia lunaris, Brodiaea pulchella, Carduus pycnocephalus), which are important nectar resources for a Californian colony of the butterflyBattus philenor as well as for other insects. The increase of the amino acid concentration in the medium is different in all four species and seems to be determined by a variety of factors including permeability of the pollen grain wall and presence or absence of pores. The results suggest a passive diffusion process of the free pollen amino acids into the medium rather than an active release. Implications from the experiments forBattus philenor and for other nectar feeding pollinators are discussed. A possible complementary effect of free pollen and nectar amino acids is proposed for plant species in which pollen is likely to be knocked into nectar by their flower visitors. A possible evolutionary pathway from nectar feeding butterflies such asBattus philenor to the complex derived pollen feeding habit in theHeliconius butterflies is proposed.     

Aquatic macroinvertebrate community structure of aNymphoides peltata-dominated and macrophyte-free site in an oxbow lake

The aquatic macroinvertebrates in two freshwater biotopes,viz. aNymphoides peltata-dominated site and a macrophyte-free site, were studied quantitatively in a shallow alkaline oxbow lake of the river Waal, the main branch of the river Rhine in The Netherlands. The research comprised the analysis of water, sediment and macrophyte samples.In the macrophyte-free site Oligochaeta and Nematocera, particularly of the collector gatherer functional feeding group, dominated the prevailing benthic community. The total macroinvertebrate biomass ranged here from 0.3 to 0.9 g ash-free dry weight per m² of biotope.Species richness, densities, and biomass of macroinvertebrates were considerably higher in the biotope dominated byNymphoides peltata. Many taxa were found associated with the aboveground macrophyte. The sediment compartment, however, contributed most to the total density and biomass of macroinvertebrates. Nematocera and Oligochaeta were the most abundant fauna groups, whereas the largest share in total biomass was provided by clams (Mollusca). The biomass of the total macroinvertebrate community in theNymphoides-dominated site ranged from 6.2 to 7.5 g ash-free dry weight per m² of biotope. The biomass of the aboveground phytophilous fauna ranged from 0.1 to 0.6 g ash-free dry weight per m² of biotope. In September, when theNymphoides peltata vegetation was in its senescent phase, the largest numbers and the highest biomass of phytophilous macroinvertebrates were observed. The contribution of the shredder functional feeding group was high in this period. This, and the overall high abundance of fauna with a detritivorous mode of life, indicates the importance of macrophyte detritus as input to food chains.     

Nectar uptake rates and optimal nectar concentrations of two butterfly species

Summary The relationship between sucrose concentration of nectar and volume uptake rate by the butterflies Agraulis vanillae (Nymphalidae) and Phoebis sennae (Pieridae) was examined. Recent theoretical models simulating feeding energetics of nectarivores have assumed that this volume uptake rate is produced by a constant but undetermined pressure drop (the difference between pressure at the proximal and distal ends of the feeding channel) at all nectar concentrations. These models predict that nectar of 20–25% sucrose maximizes the rate of energy intake and should thus be preferred by nectarivores. Data collected for Agraulis and Phoebis falsify this pressure drop assumption; both species produce greater pressure drops with increasing nectar concentration. In addition, males of both species produce greater suction pressure and uptake rates than females. This results in greater rates of energy intake for males of both species. The volume uptake rates produced by each species differ from those predicted by the models. This produces a maximal rate of energy intake at 35–40% sucrose rather than 20–25%. The empirically determined relationship between energy intake rate and nectar concentration esembles that predicted for discontinuous nectar feeders such as hummingbirds more closely than the relationship predicted for continuous suction feeders, suggesting that other basic assumptions about the feeding mechanism of butterflies should be critically examined.     

Efficiency of facultative frugivory in the nectar-feeding bat Glossophaga commissarisi: the quality of fruits as an alternative food source

The efficiency of food exploitation correlates positively with the extent of dietary specialization. Neotropical nectar-feeding bats (Glossophaginae) have one of the most specialized diets among mammals, as floral nectar constitutes a sugar-rich and highly digestible but protein and fiber depleted food source. However, dietary constraints, such as a temporary scarcity of nectar, or protein demands may sometimes require the uptake of alternative food items. We investigated the influence of a diet switch from nectar to fruit on intestinal morphology, body mass, and energy budget in the nectar-feeding bat Glossophaga commissarisi and quantified feeding efficiency. We hypothesized that these nectar specialists depend on a constant supply of nectar, if they were lacking the ability for morphological and physiological plasticity in response to a fiber-rich diet. Although capable of harvesting infructescences of Piper hispidum, G. commissarisi was less efficient in extracting energy from fruits (48% digestive efficiency of total fruit energy content) than from nectar (c. 99% digestive efficiency). The intestinal morphology and organ masses did not change after bats were switched from nectar to fruits. Captive bats exhibited lower daily energy expenditures and flight activity when feeding on fruits than during nectarivory. Possibly, this may have been a deliberate regulation to balance reduced feeding efficiency, or simply the consequence of extended digestive pauses. The low digestibility of Piper, in combination with slow digestion and the bats’ inability for morphological and physiological plasticity may cause nectar-feeders to reduce their maximum energy expenditure when feeding on fruits. We argue that although fruits may substitute for nectar, they may cause restricted maximum energy assimilation compared with nectar.     

Can nectar properties explain sex‐specific flower preferences in the Adonis Blue butterfly Lysandra bellargus?

1. Field observations in the Swiss Jura mountains showed that males and females of the bivoltine Adonis Blue butterfly Lysandra bellargus Rott. differed significantly in their flower visitation patterns. 2. In both generations, females visited a broader range of available nectar plants than did males. The specific flower visitation patterns of males and females were not affected by the general availability and abundance of potential nectar plant species during both flight periods, indicating high selectivity for nectar plants by both males and females. 3. In addition, the sexes differed in their nectar foraging behaviours: distances between successively visited flowers were significantly longer in males than in females, indicating that male and female butterflies have different foraging strategies. 4. Investigations of nectar characteristics showed that the sexes preferred flowers with different nectar compositions. Males of both generations preferred flowers with high proportions of sucrose and high amounts of total sugar, whereas females preferred flowers with high portions of glucose in their nectar, and, in the spring generation, flowers rich in amino acids. 5. Flowers visited exclusively by males or females in spring differed significantly in their amino acid composition. 6. This clear‐cut pattern did not hold for the autumn generation, most probably due to the limited availability of flowers. 7. The observed nectar foraging patterns underline the importance of adult feeding for longevity and reproduction in butterflies. The findings are particularly relevant for conservation, because L. bellargus is an increasingly threatened species in many European countries.     

Modelling potential biotope composition on a regional scale revealed that climate variables are stronger drivers than soil variables

Aim

Environmental conditions define the suitability of an area for biotopes, and any area can be suitable for several biotopes. However, most previous studies modelled the distribution of single biotopes ignoring the potential co-occurrence of biotopes in one area, which limits the usefulness of such models for conservation and restoration planning. In this study, we described the potential biotope composition of an area in response to environmental conditions.

Location

Bavaria, Federal State of Germany.

Methods

Based on the Bavarian biotope mapping data, we modelled the distribution of 29 terrestrial biotopes based on six climate variables and six chemical and four physical soil properties using the species distribution modelling algorithm Maxent.

Results

For most biotopes, we found that climate variables were more important than soil variables for the biotope distribution and that the area of the predicted biotope distribution was larger than the observed distribution. The potential biotope composition illustrated that while 8% of the area in Bavaria was not sufficiently suitable for any analysed biotope, 92% of the modelled area in Bavaria was suitable for at least one biotope, 84% for two and 77% for at least three biotopes. The difference in suitability between the most suitable biotopes in composition was minor. Further, over one-quarter of the modelled area was suitable for 6–8 different biotopes.

Main Conclusions

Our study showed that considering a composition of potentially suitable biotopes in a raster cell, instead of only the most suitable biotope, provides valuable information to identify conservation priorities and restoration opportunities.     

栖息地质量对两种网蛱蝶集合种群结构和分布的影响

在河北省赤城县研究了栖息地质量对大网蛱蝶Melitaea phoebe和金堇蛱蝶Euphydryas aurinia两种网蛱蝶集合种群结构和分布的影响。这两种网蛱蝶在约10 km_²的区域内共存,成虫期的蜜源植物几乎相同,大网蛱蝶的发生峰期比金堇蛱蝶晚约一个月,两者只有不到一周左右的时间重叠。大网蛱蝶和金堇蛱蝶幼虫的寄主植物分别是: 祁州漏芦（菊科）和华北蓝盆花（川续断科）。蜜源植物的丰度与两种网蛱蝶的局域种群大小呈正相关;祁州漏芦的密度对大网蛱蝶的局域种群大小影响很大,金堇蛱蝶的局域种群大小则与其寄主植物华北蓝盆花的高度正相关;斑块内平均植被高度与两种网蛱蝶的局域种群大小均呈正相关,植物多样性、植物均匀性和植被盖度均与金堇蛱蝶的局域种群大小负相关,与大网蛱蝶的关系不大。同时分析了其他因子如斑块的坡向、坡度等的影响。主要结论是：1）幼虫寄主植物的不同和成蝶飞行峰期的分离允许两种网蛱蝶在这样一个小的斑块区域内共存;2）蜜源是重要的限制因子,并且受气候随机性的影响很大,蜜源的波动可以很好地解释网蛱蝶集合种群在年度间的动态变化;3）大网蛱蝶和金堇蛱蝶的飞行、食物搜寻能力的不同以及各自寄主植物的生物学特性、空间分布的不同决定了它们具有不同的集合种群结构： 金堇蛱蝶是经典的集合种群,大网蛱蝶是源-汇集合种群;4）斑块质量和昆虫行为共同决定了两种网蛱蝶的集合种群结构和分布。