Agricultural land use and black fly (Diptera,Simuliidae) species richness and species assemblages in tropical streams,Northeastern Thailand

Habitat degradation through agricultural land use is the major factor threatening lotic ecosystems. Although black flies are major components of these ecosystems, the impact of agricultural land use on species diversity and species assemblages has been largely ignored in tropical streams of the Oriental region. The objectives of this study are to examine patterns of species distribution and species richness and to compare black fly species richness and species assemblages in forest and agricultural streams in Thailand. A total of 143 collections were made from 70 stream sites between June 2007 and May 2008. Whereas 19 black fly species found in these collections were all found in forest sites, only 13 species were found in agricultural sites. High species richness was associated with larger, faster, and cooler streams with larger streambed particles and the presence of riparian trees. Logistic regression analyses revealed that stream size, velocity, and riparian vegetation are among the most important factors determining patterns of spatial distribution. The results are largely consistent with studies in other zoogeographic regions, suggesting the existence of general rules for black fly species distributions. Comparisons of the physicochemical conditions between forest and agricultural streams indicated that streams in agricultural areas are warmer, with higher conductivity and fewer riparian trees. Species richness was significantly higher in forest than in agricultural streams (t = 3.61, P < 0.001). Streams in forest areas were predominantly occupied by S. siamense (73%) but other species were also found at a relatively high frequency (>20%) of the sampling sites. In contrast, streams in agricultural areas were predominantly occupied by S. aureohirtum (>80%) among the sole black fly species at 27% of the sites. The results indicate that agricultural land use has a significantly detrimental impact on black fly diversity and species assemblages. Handling editor: D. Dudgeon     

Large extents of intensive land use limit community reorganization during climate warming

Climate change is increasingly altering the composition of ecological communities, in combination with other environmental pressures such as high‐intensity land use. Pressures are expected to interact in their effects, but the extent to which intensive human land use constrains community responses to climate change is currently unclear. A generic indicator of climate change impact, the community temperature index (CTI), has previously been used to suggest that both bird and butterflies are successfully ‘tracking’ climate change. Here, we assessed community changes at over 600 English bird or butterfly monitoring sites over three decades and tested how the surrounding land has influenced these changes. We partitioned community changes into warm‐ and cold‐associated assemblages and found that English bird communities have not reorganized successfully in response to climate change. CTI increases for birds are primarily attributable to the loss of cold‐associated species, whilst for butterflies, warm‐associated species have tended to increase. Importantly, the area of intensively managed land use around monitoring sites appears to influence these community changes, with large extents of intensively managed land limiting ‘adaptive’ community reorganization in response to climate change. Specifically, high‐intensity land use appears to exacerbate declines in cold‐adapted bird and butterfly species, and prevent increases in warm‐associated birds. This has broad implications for managing landscapes to promote climate change adaptation.     

Multiple host-ant use by the predatory social parasite <Emphasis Type="Italic">Phengaris</Emphasis> (=<Emphasis Type="Italic">Maculinea</Emphasis>) <Emphasis Type="Italic">arion</Emphasis> (Lepidoptera,Lycaenidae)

Phengaris (=Maculinea) arion is an endangered social parasite of Myrmica ants, and for a very long time was considered as specific to Myrmica sabuleti. Previous studies carried out in Poland suggested some discrepancies within this assumption, and therefore a much more intensive survey was undertaken. The host ant use of P. arion was studied at five sites in different types of biotopes in Poland, i.e. xerothermal grasslands where Thymus pulegioides was used as a larval food plant by the butterfly, and more or less sandy biotopes with Thymus serpyllum. Altogether nine Myrmica species were recorded, and considerable variation in species composition and density of nests was recorded. At four localities M. sabuleti proved to be the most common ant. A total of 529 Myrmica nests were examined, and only 20 of them contained larvae and pupae of P. arion. Host ants belonged to five different species, i.e. M. sabuleti, Myrmica scabrinodis, Myrmica schencki, Myrmica lobicornis and Myrmica hellenica. Only at one site (NE Poland) was a significant heterogeneity in parasitation rates among Myrmica species detected. M. lobicornis was the most often infested ant there, which may suggest local specialisation of the butterfly. Overall low parasitism rates may explain the vulnerability of P. arion in Central Europe but further studies are also necessary.     

Dispersal and gene flow in the rare, parasitic Large Blue butterfly Maculinea arion

Dispersal is crucial for gene flow and often determines the long‐term stability of meta‐populations, particularly in rare species with specialized life cycles. Such species are often foci of conservation efforts because they suffer disproportionally from degradation and fragmentation of their habitat. However, detailed knowledge of effective gene flow through dispersal is often missing, so that conservation strategies have to be based on mark–recapture observations that are suspected to be poor predictors of long‐distance dispersal. These constraints have been especially severe in the study of butterfly populations, where microsatellite markers have been difficult to develop. We used eight microsatellite markers to analyse genetic population structure of the Large Blue butterfly Maculinea arion in Sweden. During recent decades, this species has become an icon of insect conservation after massive decline throughout Europe and extinction in Britain followed by reintroduction of a seed population from the Swedish island of Öland. We find that populations are highly structured genetically, but that gene flow occurs over distances 15 times longer than the maximum distance recorded from mark–recapture studies, which can only be explained by maximum dispersal distances at least twice as large as previously accepted. However, we also find evidence that gaps between sites with suitable habitat exceeding ～20 km induce genetic erosion that can be detected from bottleneck analyses. Although further work is needed, our results suggest that M. arion can maintain fully functional metapopulations when they consist of optimal habitat patches that are no further apart than ～10 km.     

Population isolation rather than ecological variation explains the genetic structure of endangered myrmecophilous butterfly Phengaris (=Maculinea) arion

Genetic variation of the globally threatened obligatorily myrmecophilous Large Blue butterfly Phengaris (Maculinea) arion (Lepidoptera) was studied, using six microsatellite markers, in a country where its decline is dramatic (Poland). Material was collected on 13 sites showing considerable ecological variation as far as biotope, larval food plant and host ants of the butterfly were concerned. Genetic variability, estimated in terms of number of alleles and heterozygosity, was the lowest in the most isolated populations. However on sites localized in areas where suitable biotopes were extensive and interconnected, P. arion still held relatively high genetic diversity. Pairwise F _ST values indicated small and moderate differentiation among samples (F _ST = 0.01–0.15), with the exceptions of two isolated localities (0.20). We did not find clear evidence of isolation by distance. The presence of four or five genetic clusters was indicated. Analysis of the membership of each individual to each cluster showed that the vast majority of individuals from three isolated populations were clustered in three separate genetic groups. The most distinct population was the one, which had been found to be specialized towards Myrmica lobicornis in previous studies. Individuals from the remaining populations could not be clustered in separate genetic groups, however some dominance of different clusters in geographical regions was observed. Some portion of the population’s genetic variability could be explained by geographical distribution, however the percentage of variation, explaining the differences between two main regions (S and NE Poland), was very low. We conclude that the main factor shaping the current genetic structure of P. arion in Poland is the recent isolation of populations related to habitat fragmentation but local ecological specializations may be also a potential factor. Therefore the necessity of activities aiming to halt the further reduction of genetic variability, as well as the monitoring of priority populations (e.g. those belonging to unique host races), should be emphasized in future action plans in Central Europe.     

Dispersal and microsite limitation of a rare alpine plant

Knowledge on the limitation of plant species’ distributions is important for preserving alpine biodiversity, particularly when the loss of alpine habitats because of global warming or land use changes is faster than colonization of new habitats. We investigated the potential of the rare alpine plant Campanula thyrsoides L. to colonize grassland sites of different suitability on a small mountain plateau in the Swiss Alps. A total of 15 experimental sites were selected according to their differences in habitat suitability for adult C. thyrsoides, which was measured by the Beals index. At each site we applied a disturbance treatment, added seeds at different densities and monitored the survival of seedlings over two consecutive years. The number of surviving seedlings was not positively related to habitat suitability for adult C. thyrsoides. Furthermore, C. thyrsoides appears to be strongly dispersal limited at the regional scale because seed addition to unoccupied habitats resulted in successful germination and survival of seedlings. Since an increase of seed density in already occupied sites did not affect the number of seedlings, we suggest that C. thyrsoides is microsite limited at the local scale. Microsite limitation is supported by the result that seedling survival of the species was enhanced in vegetation gaps created by disturbance. We conclude that C. thyrsoides may become endangered in the future if environmental changes cause local extinction of populations. An appropriate management, such as a disturbance regime for enhancing recruitment in existing populations, may ensure the long-term survival of this rare alpine plant species.     

Riparian Butterfly (Papilionoidea and Hesperioidea) Assemblages Associated with Tamarix-Dominated, Native Vegetation–Dominated, and Tamarix Removal Sites along the Arkansas River, Colorado, U.S.A.

We studied butterfly assemblages at eight riparian sites over five years. Sites included Tamarix spp.–dominated riparian areas; sites where mechanical means or biological control agents (Diorhabda elongata deserticola) were used to limit Tamarix; sites that were mixtures of native woody vegetation (e.g., Populus and Salix) and Tamarix; and native vegetation sites. We identified a gradient in butterfly community composition that changed from treated Tamarix sites, through mixed vegetation, to native vegetation sites. Tamarix sites had lower butterfly metric (riparian butterfly index [RBI]) values than did native vegetation sites. The RBI is based on a combination of richness measures and the presence of specific species and groups of butterflies. There was no significant change in the RBI over sampling periods at any sites, including both Tamarix eradication sites. The RBI at sites where Tamarix control took place did not approach restoration goals based on values at unimpacted sites. Positive effects on riparian butterfly assemblages were not linked to any Tamarix control efforts, nor did we detect a decline from initial butterfly metrics at Tamarix sites. Direct ordination provided information on environmental variables, such as amount of nectar and herbaceous plant richness, which may be important in riparian restoration efforts.     

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.     

Regional hotspots of butterfly diversity in a protected area: Are they indicators of unique assemblages and areas with more species of conservation concern?

The implementation of biodiversity studies to set conservation priorities assumes that the different criteria used in prioritisation are correlated. Based on butterfly data, we examined whether high total diversity (species density and richness), unique species assemblages, and high numbers of different categories of Species of European Conservation Concern (SPEC) were co-located in the same habitats in the Picos de Europa National Park, Spain. Species density (number of species per sample) declined with elevation and was significantly higher in Genista shrublands on southern slopes (Southern Genista shrubland). We found unique species assemblages for Southern Genista shrublands, heathlands, mown meadows and subalpine meadows, whereas Genista shrubland on northern slopes (Northern Genista shrubland) and pastures were occupied by more habitat generalist species. We also found an effect of elevation on species composition. Species with global distributions concentrated in Europe (SPECs 4b) tended to be associated with Southern Genista shrubland, whereas species with global distributions restricted to Europe (SPECs 4a) were associated with higher elevations. Thus, we suggest a higher conservation value for butterfly assemblages located both on Southern Genista shrublands and at high elevations as they contain unique assemblages with a higher number of SPECs. By comparing our data with a previous study on carabid beetles, we found a low coincidence between butterflies and beetles for habitats with high species diversity and unique assemblages. Our study suggests that preserving areas in the landscape supporting higher butterfly diversity only partially preserves those species of greater conservation concern, and that butterflies cannot be used as a reliable indicator of other priority taxa for conservation, such as carabid beetles.     

Effect of Tree‐Fall Gaps on Fruit‐Feeding Nymphalid Butterfly Assemblages in a Peruvian Rain Forest

One of the main natural disturbances that affects the structure of rain forests is treefalls, frequently resulting in gaps. Tree‐fall gaps can bring drastic changes in environmental conditions compared with the undisturbed understory. We investigated the effect of tree‐fall gaps on fruit‐feeding butterfly (Nymphalidae) species assemblages in an undisturbed lowland rain forest in southeastern Peru. We used fruit‐baited traps suspended 2 m above ground in 15 tree‐fall gaps ranging in area from 100 to 1000 m² and in adjacent undisturbed understory. Our data support the hypothesis that tree‐fall gap and understory habitats are utilized by different butterfly species assemblages. There were morphological differences between gap and understory species, where the understory species had a larger wing area to thoracic volume. Vegetation structure and composition were important factors affecting the butterfly assemblages. Most of the butterfly species showed an avoidance of vines and a strong association with the presence of trees and shrubs in gaps. There were also differences among gap assemblages that increased with gap size. Some of the species that were associated with gaps have been considered as canopy species. Other gap species in the present study, however, are known to feed on fruits and/or use host plants mainly, or only, occurring in gaps, implicating that the gap assemblage is a mix of canopy species and those unique to gaps. This indicates that, in an undisturbed Amazon forest, tree‐fall gaps may contribute to maintain species diversity by creating a mosaic of specific habitats and resources that favors different butterfly assemblages.     

Improving conservation and management of the imperiled Carson Valley silverpot butterfly <Emphasis Type="Italic">Speyeria nokomis carsonensis</Emphasis> (Lepidoptera: Nymphalidae) based on rapid assessments of distribution,habitat, and threats

The immediacy of conservation decisions for imperiled species often requires rapid assessments of fundamental species-specific data to appropriately guide conservation resources, regulatory actions, and mitigation activities. The goal of this paper was to inform future conservation and management decisions for the imperiled Carson Valley silverspot butterfly (Speyeria nokomis carsonensis), a species that has been subject to conservation attention, yet very little is known about its distribution and habitat. Surveys for S. nokomis carsonensis and its habitat were conducted during 2004–2005. An 88% decline in the number of historic subpopulations was observed, but 30 new subpopulations were discovered. Among the 62 sites that either had populations or were considered potentially suitable habitat, three distinct habitat types were delineated: agricultural seeps, isolated springs, and riparian meadows. Riparian sites comprised 58% of all sites and little variation was observed in the proportion of occupancy across habitat types. Disturbance was substantially greater in unoccupied sites than in sites occupied by S. nokomis carsonensis. Livestock grazing was the primary threat (50% of sites) to habitat, while water diversions were a secondary threat (7 sites). The variability in habitat and threats identifies that even for highly specialized subspecies, all habitats simply cannot be considered equal candidates for inclusion in a conservation strategy for the butterfly. Adopting proactive management policies that conserve suites of sites within each habitat type and reduce grazing intensity within S. nokomis carsonensis habitats should be a priority to reduce threats and circumvent a prospective listing pursuant to the US Endangered Species Act.     

The comparative reproductive biology of a tetraploid species,Hedychium villosum,and its diploid progenitor H. tenuiflorum (Zingiberaceae)

The evolutionary advantages of polyploidy may result from a number of changes in floral traits and breeding system, which may enable polyploids to exploit new habitats and become widespread. In this study, we comparatively investigated the floral biology of the tetraploid species Hedychium villosum and its diploid progenitor H. tenuiflorum, to assess reproductive divergence between the two species. The results showed that flowers of the tetraploid species last longer and produce more nectar than did diploid species. The flowering times of the two species did not overlap at all. Observations of floral visitors in natural populations demonstrated that butterflies and hawkmoths were effective pollinators of both species, but there was a significant difference in butterfly and hawkmoth assemblages between the two species. The hand‐pollination experiments and pollen tube growth experiments suggested that diploid H. tenuiflorum was self‐incompatible, while tetraploid H. villosum was completely self‐compatible. H. villosum has a much wider distribution range and occupies more diverse habitats than H. tenuiflorum. Polyploidisation may enable tetraploid H. villosum to exploit new habitats previously unavailable to diploid H. tenuiflorum.     

Patch occupancy in the endangered butterfly Lycaena helle in a fragmented landscape: effects of habitat quality, patch size and isolation

While there is agreement that both habitat quality and habitat network characteristics (such as patch size and isolation) contribute to the occupancy of patches by any given species, the relative importance of these factors is under debate. This issue is of fundamental ecological importance, and moreover of special concern for conservation biologists aiming at preserving endangered species. Against this background we investigated patch occupancy in the violet copper Lycaena helle, one of the rarest butterfly species in Central Europe, in the Westerwald area (Rhineland-Palatinate, Western Germany). Occupied (n = 102) differed from vacant (n = 128) patches in altitude, size, connectivity, availability of wind shelter, in the abundance of the larval host-plant, in the abundance of a grass species indicating favorable habitat conditions and in the abundance of nitrophilous plants. Overall, patch occupancy was primarily determined by patch size, connectivity and the abundance of the larval host plant, while all other parameters of habitat quality were of subordinate importance. Therefore, our findings suggest that even for extremely sedentary species such as L. helle habitat networks are decisive and—next to the preservation of habitat quality—need to be an integral part of any conservation management for this species.     

Patterns of Ephemeroptera taxa loss in Appalachian headwater streams (Kentucky,USA)

Mayflies (Insecta: Ephemeroptera) are common inhabitants of streams throughout the Appalachian Mountains. Headwater mayfly assemblages were evaluated with respect to regional landuse disturbances (coal mining and residential) in eastern Kentucky, USA. Estimates of mayfly taxa richness and relative abundance were compared at 92 sites represented by least-disturbed reference (REF; n = 44), residential only (RESID; n = 14), mixed residential and mining (MINED/RESID; n = 14), and mining only (MINED; n = 20) landuse categories. A total of 48 species from 27 genera and 9 families were identified; Ephemerella, Epeorus, Ameletus, Cinygmula, and Paraleptophlebia comprised the core 5 genera most frequently encountered at REF sites. These same genera (among others) were often reduced or extirpated from other landuse categories. Mean mayfly richness and relative abundance were significantly higher at REF sites compared to all other categories; MINED sites had significantly lower metric values compared to RESID and MINED/RESID sites. Relative mayfly abundance was most strongly correlated to specific conductance (r = 0.72) compared to total habitat score (r = 0.59), but relationships varied depending on landuse category. Non-metric multidimensional scaling (for mayfly taxa) and principal components analysis (for environmental variables) separated REF sites strongly from most other sites. The results indicate that expected mayfly communities are disappearing from streams where mining disturbance and residential development has occurred and because of the long-term impacts incurred by both landuses, recovery is uncertain.     

Complexity of species conservation in managed habitats: interaction betweenMaculinea butterflies and their ant hosts

Europe's five species ofMaculinea butterfly are examples of endangered species adapted to live in traditional, cultural landscapes. All are threatened with extinction in Western Europe because of recent changes in land use. This is illustrated by an historical account of the extinction of the BritishMaculinea arion populations, despite many conservation attempts. It is shown how the failures proved to be due to ignorance of the key factor forM. arion, its specialization on a single ant host,Myrmica sabuleti. A brief account is given of research that shows how each of the five species is similarly dependent upon a separate hostMyrmica ant species and how each has an interesting and rare specific parasitoid. Steps for the practical conservation of existingMaculinea populations including the obligation, under the Bern Convention, to re-establish nationally extinct species are outlined. The procedure and problems involved in re-establishment are illustrated with reference to the successful programme forM. arion in Britain. The best way of ensuring robust populations ofMaculinea butterflies is to manage habitats to optimize the density and distribution of the required species ofMyrmica host and, secondarily, the distribution of the larval food plant. The value of single species conservation in cultural habitats is discussed. It is concluded that this is possible to achieve and that other rare organisms also often benefit, but only when conservation measures are based on the results of detailed autecological research.     

Habitat preferences of Maculinea arion and its Myrmica host ants: implications for habitat management in Italian Alps

Projections of climate-change scenarios indicate that many Maculinea arion populations will disappear from Europe over the next 50 years. Extinctions will be particularly concentrated around the southern limits of the species?? range, such as the Italian peninsula, except mountain populations, mainly in the Alps. M. arion is a social parasite of Myrmica ants and its survival depends on the presence and abundance of two resources, i.e. (1) a specific larval foodplant and (2) a suitable Myrmica host ant. We collected data on Thymus plants distribution, Myrmica ants abundance, turf height around Myrmica nests, distance between nests and the closest thyme plant (Thymus pulegioides), and vegetation structure at 14 patches of a M. arion fragmented population occurring in the Western Italian Alps (Val Ferret: Aosta). We found that patches with the highest abundance of M. arion had significantly higher foodplant abundance. Among 407 nests belonging to nine Myrmica species, we found M. arion larvae in one Myrmica lonae and in two Myrmica sulcinodis nests. The distribution of M. sulcinodis nests showed the best spatial overlap with Thymus plants. M. sulcinodis was also significantly more abundant on pastures showing high M. arion density, and therefore offered higher adoption probabilities to develop butterfly larvae. On M. arion habitat patches, the mean turf height around Myrmica nests varied from 10.5 to 22.3 cm and best matched the habitat requirements of T. pulegioides. Thus, we suggest that extensive grazing is needed to maintain the two most important resources for M. arion. Moreover, patches where M. arion was abundant included more numerous plant species characteristic of these mountain pastures, as well as higher plant diversity (Shannon index). As a consequence, M. arion represents an umbrella species and a good indicator for the conservation status of mountain grasslands.     

Seed dispersal and realized gene flow of two forest orchids in a fragmented landscape

• Species with vast production of dust‐like windborne seeds, such as orchids, should not be limited by seed dispersal. This paradigm, however, does not fit recent studies showing that many sites suitable for orchids are unoccupied and most seeds land close to their maternal plant. To explore this issue, we studied seed dispersal and gene flow of two forest orchid species, Epipactis atrorubens and Cephalanthera rubra, growing in a fragmented landscape of forested limestone hills in southwest Bohemia, Czech Republic.
• We used a combination of seed trapping and plant genotyping methods (microsatellite DNA markers) to quantify short‐ and long‐distance dispersal, respectively. In addition, seed production of both species was estimated.
• We found that most seeds landed very close to maternal plants (95% of captured seeds were within 7.2 m) in both species, and dispersal distance was influenced by forest type in E. atrorubens. In addition, C. rubra showed clonal reproduction (20% of plants were of clonal origin) and very low fruiting success (only 1.6% of plants were fruiting) in comparison with E. atrorubens (25.7%). Gene flow was frequent up to 2 km in C. rubra and up to 125 km in E. atrorubens, and we detected a relatively high dispersal rate among regions in both species.
• Although both species occupy similar habitats and have similar seed dispersal abilities, C. rubra is notably rarer in the study area. Considerably low fruiting success in this species likely limits its gene flow to longer distances and designates it more sensitive to habitat loss and fragmentation.

     

Protecting a single endangered species and meeting multiple conservation goals: an approach with Guaiacum sanctum in Yucatan Peninsula,Mexico

Aim New protected areas should consider safeguarding high conservation value sites based on multiple criteria and not just the presence of a single endangered or charismatic species. However, the extent to which complementary criteria coincide is usually unknown. We use the case of Guaiacum sanctum (Zygopyllaceae), an endangered timber tree species, to explore whether the protection of forests where this species is most abundant would meet other complementary conservation goals, such as capturing regional plant biodiversity, protecting other threatened/endemic species or safeguarding ecosystem services. Location Yucatan Peninsula, southern Mexico. Methods We conducted an analysis of the structure, composition and diversity of tree communities (including stems ≥5 cm dbh) at eight G. sanctum forest sites. We identified endemic and threatened tree species and quantified above‐ground tree biomass and carbon storage in these G. sanctum forests. Results Guaiacum sanctum forests contain 35–59 tree species on plots as small as 1000 m². The species composition of tree communities changed rapidly (high β‐diversity) across soil boundaries and rainfall regimes. Twenty‐one endemic and eight threatened tree species were recorded in our inventories. Individuals of G. sanctum represented up to 55% of the above‐ground carbon for trees ≥5 cm dbh. The high basal area of G. sanctum forests plus the high wood density, abundance, large size and longevity (more than 500 years) of G. sanctum and other tree species enhance the potential importance of these forests for carbon storage. Main conclusions A conservation strategy focused on protecting important populations of G. sanctum in the Yucatan Peninsula would have significant co‐benefits for conservation of regional tree species biodiversity and provision of critical ecosystem services. Our study illustrates a multiple criteria approach useful for the selection of areas with high conservation value on the basis of endemic, threatened species, species richness and ecosystem services.     

Winter habitat use by Loggerhead Shrikes (Lanius Ludovicianus) in Mexico: separating migrants from residents using stable isotopes

Several species of migrant birds overlap in range on their wintering grounds with non-migrant conspecifics or other species that occupy a similar niche. Very little is known whether such overlap results in competition and subsequent habitat segregation since it is usually impossible to separate resident from migrant individuals. The Loggerhead Shrike (Lanius ludovicianus) is a declining grassland species in North America that winters in the southern United States and Mexico. Using stable-hydrogen isotope (δD) analysis of feathers, we identified resident and migrant shrikes wintering in northeastern Mexico based on a latitudinal gradient in precipitation and feather δD values. Indicator species analyses showed that migrants occupied areas where bare ground was less available than those occupied by residents, a pattern which held when a more restricted set of birds from the extremes of the δD distribution were considered. This provides evidence for conspecific habitat segregation. Habitat differences were also found between sites occupied by shrikes and apparently suitable but unoccupied sites. Shrikes occupied more open sites that contained shorter tall shrubs and huisache (Acacia farneasiana) and fewer tall shrubs, mesquite (Prosopsis glandulosa) and huisache than unoccupied sites. The availability of suitable winter habitat and the potential competition between migrants and residents may be factors that influence the population dynamics of migrant shrikes in North America.     

Characteristics of the breeding habitat of Endangered Kirtland's Warblers on a Canadian Military Installation

Kirtland's Warblers (Setophaga kirtlandii) are an endangered species with specialized habitat requirements, and the only documented nesting location in Canada is an Army installation. From 2007 to 2010, I compared habitat characteristics of sites occupied and not occupied by Kirtland's Warblers at Garrison Petawawa located ～200 km northwest of Ottawa, Ontario. Sites occupied by Kirtland's Warblers (N = 11) had greater percent cover of low sweet blueberry (Vaccinium angustifolium; 31.2%), coral lichen (Cladina stellaris; 0.4%), reindeer lichen (Cladonia rangiferina; 8.3%), and wavy‐leaved moss (Dicranum polysetum; 4.3%) than unoccupied sites (N = 6). I found no difference in tree species composition between sites, with jack pine (Pinus banksiana), white pine (Pinus strobus), red pine (Pinus resinosa), poplar (Populus tremuloides), and red maple (Acer rubra) present in both used and unused sites. Forest stands occupied by Kirtland's Warblers were significantly younger (< 20 yr old) than unoccupied sites, and most occupied sites were within former fire zones and sites where jack pines had been planted. Thus, breeding habitat of Kirtland's Warblers in Canada consisted of young pine trees, with more red pine than in their breeding habitat in Michigan, and ground cover including blueberry, lichens, and mosses. These results suggest that Kirtland's Warblers may be less selective in their habitat requirements than previously thought, and should provide guidance for recovery groups and regulatory agencies in accurately delineating suitable habitat for these warblers in Canada.