Resource utilization, overlap and temporal dynamics in a guild of mountain stream insects

SUMMARY 1. Resource utilization was quantified for six mayfly (Ephemeroptera) and one caddis (Trichoptera) species comprising a lotic scraper/collector-gatherer guild across three niche dimensions (temporal, trophic and spatial). Based on trophic differences and inferred microspatial utilization, the members of this guild separated into two groups: (1) cryptic detritivores and (2) exposed algivores.
2. Each species demonstrated a slow seasonal univoltine life cycle except for Epeorus longimanus (Eaton) and Baetis iricaudatus (Dodds) which were fast seasonal univoltine and multivoltine, respectively.
3. Temporal sequencing of periods of peak resource utilization were not demonstrated by the members of this guild. A null analysis indicated that periods of peak resource utilization were aggregated.     

Do competitive intraguild interactions affect space and habitat use by small carnivores in a forested landscape?

Complex interactions such as interference competition and predation, including intraguild predation, are now recognized as important components in animal community structure. At the lower end of a guild, weasels may be highly affected by other guild members due to small body size in relation to other predators. In 2000 and 2001, we radio-collared 24 ermines Mustela erminea and 25 long-tailed weasels M. frenata in 2 areas that differed in abundance of guild members. We tested the hypothesis that when faced with an increased density of other guild members, weasels would modify space and habitat use to reduce the risk of predation associated with encounters involving guild members. We predicted that weasels would increase use of specific habitats (such as refuges) to reduce encounter rates in the presence of a greater number of guild members. Because M. erminea is smaller than M. frenata and thus better able to take advantage of small rodent burrows as refuges from predators and as feeding grounds, we also predicted that M. frenata would show a stronger response to a higher abundance of guild members than M. erminea . Results were consistent with our predictions. Faced with an increased abundance of guild members, M. frenata showed increased habitat selectivity and reduced activity levels, which resulted in increased daily travel distances and increased home ranges. Mustela erminea responded to an increased abundance of guild members through reduced use of preferred habitat which M. frenata already occupied. The contrasting pattern of habitat selection observed between the 2 mustelid species suggested cascading effects, whereby large-predator pressure on M. frenata relaxed pressure of M. frenata on M. erminea . Our results draw attention to the likelihood that competitive intraguild interactions play a facilitating role in M. erminea – M. frenata coexistence.     

Population Dynamics of the Polychaetous Annelids of an Intertidal Habitat in Upper Old Tampa Bay,Florida

Following an extensive red-tide induced mass mortality of the benthic macrofauna of a sandy intertidal habitat, the population dynamics of the polychaete species were studied. Detailed studies of the 12 most abundant species are presented. Data concerning total population levels, reproduction, recruitment, distribution within the intertidal zone, and gut content analyses are integrated in order to explain the observed spatial and temporal patterns of distribution and abundance. Potential competive interactions for food are considered to be the most important factor for explaining the observed ecological patterns. The polychaete species studied are divided into three trophic guilds: an omnivorous guild that feeds predaciously and as non-selective deposit feeders, a surface feeding guild consisting of species usually considered to be selective surface deposit feeders, and a subsurface feeding guild usually considered as non-selective infaunal deposit feeders. Within and between guild interactions are discussed.     

Nonlinear time series analysis unravels underlying mechanisms of interspecific synchrony among foliage-feeding forest Lepidoptera species

Interspecific synchrony, that is, synchrony in population dynamics among sympatric populations of different species can arise via several possible mechanisms, including common environmental effects, direct interactions between species, and shared trophic interactions, so that distinguishing the relative importance of these causes can be challenging. In this study, to overcome this difficulty, we combine traditional correlation analysis with a novel framework of nonlinear time series analysis, empirical dynamic modeling (EDM). The EDM is an analytical framework to identify causal relationships and measure changing interaction strength from time series. We apply this approach to time series of sympatric foliage-feeding forest Lepidoptera species in the Slovak Republic and yearly mean temperature, precipitation and North Atlantic Oscillation Index. These Lepidoptera species include both free-feeding and leaf-roller larval life histories: the former are hypothesized to be more strongly affected by similar exogenous environments, while the latter are isolated from such pressures. Correlation analysis showed that interspecific synchrony is generally strongest between species within same feeding guild. In addition, the convergent cross mapping analysis detected causal effects of meteorological factors on most of the free-feeding species while such effects were not observed in the leaf-rolling species. However, there were fewer causal relationships among species. The multivariate S-map analysis showed that meteorological factors tend to affect similar free-feeding species that are synchronous with each other. These results indicate that shared meteorological factors are key drivers of interspecific synchrony among members of the free-feeding guild, but do not play the same role in synchronizing species within the leaf-roller guild.     

The form of direct interspecific competition modifies secondary extinction patterns in multi‐trophic food webs

Forcibly removing species from ecosystems has important consequences for the remaining assemblage, leading to changes in community structure, ecosystem functioning and secondary (cascading) extinctions. One key question that has arisen from single‐ and multi‐trophic ecosystem models is whether the secondary extinctions that occur within competitive communities (guilds) are also important in multi‐trophic ecosystems? The loss of consumer–resource links obviously causes secondary extinction of specialist consumers (topological extinctions), but the importance of secondary extinctions in multi‐trophic food webs driven by direct competitive exclusion remains unknown. Here I disentangle the effects of extinctions driven by basal competitive exclusion from those caused by trophic interactions in a multi‐trophic ecosystem (basal producers, intermediate and top consumers). I compared food webs where basal species either show diffuse (all species compete with each other identically: no within guild extinctions following primary extinction) or asymmetric competition (unequal interspecific competition: within guild extinctions are possible). Basal competitive exclusion drives extra extinction cascades across all trophic levels, with the effect amplified in larger ecosystems, though varying connectance has little impact on results. Secondary extinction patterns based on the relative abundance of the species lost in the primary extinction differ qualitatively between diffuse and asymmetric competition. Removing asymmetric basal species with low (high) abundance triggers fewer (more) secondary extinctions throughout the whole food web than removing diffuse basal species. Rare asymmetric competitors experience less pressure from consumers compared to rare diffuse competitors. Simulations revealed that diffuse basal species are never involved in extinction cascades, regardless of the trophic level of a primary extinction, while asymmetric competitors were. This work highlights important qualitative differences in extinction patterns that arise when different assumptions are made about the form of direct competition in multi‐trophic food webs.     

Network topology of stable isotope interactions in a sub-arctic raptor guild

Predation is an ecologically important process, and intra-guild interactions may substantially influence the ecological effects of predator species. Despite a rapid expansion in the use of mathematical graph theory to describe trophic relations, network approaches have rarely been used to study interactions within predator assemblages. Assemblages of diurnal raptors are subject to substantial intra- and interspecific competition. Here we used the novel approach of applying analyzes based on network topology to species-specific data on the stable isotopes ¹³C and ¹⁵N in feathers to evaluate patterns of relative resource utilization within a guild of diurnal raptors in northern Sweden. Our guild consisted of the golden eagle (Aquila chrysaetos), the gyrfalcon (Falco rusticolus), the peregrine falcon (Falco peregrinus) and the rough-legged buzzard (Buteo lagopus). We found a modular trophic interaction structure within the guild, but the interactions were less nested than expected by chance. These results suggest low redundancy and hence a strong ecological importance of individual species. Our data also suggested that species were less connected through intra-guild interactions than expected by chance. We interpret our results as a convergence on specific isotope niches, and that body size and different hunting behaviour may mediate competition within these niches. We finally highlight that generalist predators could be ecologically important by linking specialist predator species with disparate dietary niches.     

Relating Species and Community Dynamics in an Heavily Exploited Marine Fish Community

We examined the dynamics of fish species and how they relate to species assemblage coherence in the heavily exploited Georges Bank fish community. Coherence is defined as reduced temporal variability of total assemblage biomass. We assumed that a higher degree of compensation hence coherence occurs within competitively coupled species assemblages; therefore, fisheries may directly alter the dynamics of certain targeted species sizes but assemblage structure will be relatively more stable owing to compensatory interactions. Species-sizes were grouped, based on negative covariance coupling in biomass time series from survey data. Assemblages representing benthic feeders were clearly identified by this method; furthermore, the most heavily exploited species-sizes were decoupled from other species-sizes suggesting that fisheries have diminished their potential to compensate or to be compensated for by competitive interactions. Biomass of species-sizes within known trophic guilds strongly compensated other guild-member biomass fluctuations if the diet of guild members was more specialized. This is an indication that more competitive conditions (more specialization) foster greater compensatory responses between competitors biomass fluctuations.     

The Hemipepsis wasp‐pollination system in South Africa: a comparative analysis of trait convergence in a highly specialized plant guild

Pollinator‐mediated convergence in floral traits is the fundamental basis for pollination syndromes, but it has seldom been rigorously analysed. Here we synthesize information on a guild of South African plants that are pollinated by functionally similar pompilid wasps in the genus Hemipepsis and investigate the extent of trait convergence in guild members. The guild includes members from three plant families (Apocynaceae, Orchidaceae and Asparagaceae subfamily Scilloideae) and contains remarkably high levels of functional specialization with 18 of the 23 known guild members being pollinated exclusively by Hemipepsis wasps. The distribution of the guild is centred in the moist upland grasslands of eastern South Africa. Qualitative similarities among guild members include dull greenish‐ or brownish‐white flowers, often with purple blotches, mid‐summer flowering, sweet spicy scent and exposed nectar. To assess the extent of convergent evolution within the guild, we compared floral traits of guild members with those of congeneric non‐wasp‐pollinated species. Guild members typically produce moderate volumes (> 4 µL per flower per day) of concentrated (> 50% sugar by weight) sucrose‐dominant nectar. The nectar properties of guild members did not, however, differ significantly from those of congeneric species pollinated by other vectors. Non‐metric multidimensional scaling of scent data for 15 guild members and 17 congeners (obtained through gas chromatography–mass spectrometry of headspace samples and supplemented with published data) yielded little evidence for convergent evolution in the overall scent composition of guild members. However, convergence in floral spectral reflectance was evident in the guild members; in particular, loci for colours of guild members were significantly closer to the guild centroid than loci for colours of congeners, and they formed a distinct cluster in the blue to blue–green region of the hymenopteran colour hexagon. The colours of guild members were also significantly closer to the colour of background vegetation than those of congeneric species, suggesting a role for cryptic colouring in this system. These results confirm convergence in the floral colours of plants that are pollinated by Hemipepsis spider‐hunting wasps, but also suggest that other traits, such as nectar properties, do not necessarily evolve during shifts between pollination systems. Identification of particular scent compounds and non‐sugar nectar constituents that influence wasp behaviour will be essential for illuminating the extent of biochemical convergence in the guild members. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 278–299.     

Trophic Structure of One Deep-sea Benthic Fish Community in the Eastern Canadian Arctic: Application of Food, Parasites and Multivariate Analysis

Synopsis As new arctic marine fisheries develop there is need for a comprehensive ecosystem approach to long-term management. This approach recognizes the importance of community interactions such as food web structure and trophic patterns. We determined whether hierarchical clustering (guild formation) is an effective method of trophic evaluation in deep-sea Artic fish communities using stomach content and parasite data with size class, and evaluated the application of endohelminth communities (parasite species transmitted in the food) as indicators of trophic status. Cluster analysis using food group abundance with size class of fish revealed the presence of 11 guilds within the community, however the same analysis using parasite data showed little correlation between food and parasites. Redundancy analysis (RDA) within the 11 guilds also revealed no significant correlations between food group and parasite abundance suggesting that this type of ordination is not suited for environments containing mainly generalist feeders. RDA of individual taxa without a priori guild designation found that taxa in benthic deep-sea communities are defined by their ability to exploit prey species in more than one habitat zone. Benthic fish species were significantly correlated with benthic food groups and parasites that utilize benthic intermediate hosts whereas benthopelagic–pelagic species fed on a higher diversity of prey species and were infected by a larger number of non-host specific parasites. Eigenanalysis and Monte Carlo results showed that parasites and food groups are highly correlated, indicating that parasite community analysis is an effective tool for predicting feeding strategies in Arctic marine environments. It also suggests that in most cases endoparasite infections alone could be used for trophic evaluation in the absence of stomach content data.     

Effects of species vs. functional diversity: Understanding the roles of complementarity and competition on ecosystem function in a tropical stream fish assemblage

The positive effects of biodiversity on the functioning of ecosystems are well demonstrated in laboratory microcosms but the precise mechanisms underlying higher ecosystem process rates in natural assemblages are less well understood. We investigated, under semi-natural conditions (field enclosures), the potentially interactive effects of species identity and trophic function (i.e., feeding guild) on consumer growth, using a fish assemblage in a tropical stream. We tested the relative importance of species identity and trophic function on consumer growth by placing 2 fish of either (i) the same species, (ii) different species but of similar trophic function, or (iii) different species of different trophic functions in each of 72 stream enclosures for 48 days and measuring biomass change, individual diet composition and behavior. We predicted that if functional diversity had a larger impact than species diversity, then fish growth would be highest for pairs of species from different functional groups (i.e., those with the highest diet complementarity), intermediate for different species within a guild, and lowest for the same species (those with the lowest complementarity and highest niche overlap), such that functional variation between species in different guilds would exceed functional differences within guilds. Our results show that functional heterogeneity rather than species diversity per se had the greatest impact on food resources used complementarily, leading to higher biomass accrual. Mechanistically, higher growth rates were driven by concomitant increases in resource intake and reductions in antagonistic interactions. Together, these results underscore the importance of functional diversity on macroconsumer production in natural assemblages.     

Guild composition and mustelid morphology – character displacement but no character release

Aim  Competition is hypothesized to lead to the evolution of reduced morphological overlap between competitors. Within guilds, this is believed to lead to overdispersed size ratios of the trophic apparatus of adjacent-sized species. In allopatry, conditions are believed to favour character release. We examined whether character displacement is prevalent in mainland musteline guilds and sought evidence for character release in adjacent island guilds.
Location  Holarctic, from Japan through western Europe to Pacific North America.
Methods  We measured skulls and canines of members of the mustelid subfamily Mustelinae and examined whether size ratios tend towards equality. We then examined whether insular guilds are characterized by larger size ratios and a higher degree of sexual size dimorphism than mainland guilds, and whether this reflects evolution towards the size of missing guild members.
Results  We found equal ratios between skull lengths but not canine diameters in all mainland guilds. Few insular guilds showed equal ratios for either trait. There was scant evidence for character release: insular mustelines do not evolve towards the size of a missing guild member, nor is sexual size dimorphism greater on islands. There was no evidence for a lower limit on the size similarity of co-existing mustelids.
Main conclusions  We propose that different guild compositions in different localities produce different evolutionary trajectories. Similar sizes on islands and mainlands can be explained by similar prey sizes in both settings. Morphological evidence suggests that competition is probably not a ubiquitous force in the assembly and evolution of musteline guilds.     

Interactions potentially affecting the seasonal abundance of selected aquatic invertebrates in a rice field habitat

Variables associated with the seasonal abundance of members of a prey complex consisting of Chironomidae, Corixidae and Crustacea, and of a predator guild including Belostomatidae, Dytiscidae, Hydrophilidae and Notonectidae sampled from California rice fields were evaluated by multiple regression analysis. Variables included water temperature, rice plant stand and potential predator-prey interactions. Regression equations using water temperature and rice plant stand as independent variables described the seasonal abundance of both the prey complex (F = 5.619; P = 0.025) and the predator guild (F = 9.037; P = 0.005). Predator-prey interactions further modified many of the seasonal patterns of the organisms observed.     

How ecological neighbourhoods influence the structure of the scavenger guild in low arctic tundra

Aim How the ecological neighbourhoods of coast and forest affect arctic tundra ecosystems is a pressing question as the circumpolar tundra belt is shrinking under global warming. Mobile facultative scavengers are likely to negatively impact tundra biodiversity as dominant competitors or predators, if they spill over into tundra. Here, we provide the first quantitative assessments of the structure of a scavenger guild in low arctic tundra with emphasis on how it changes along spatial gradients from neighbouring ecosystems (i.e. forest and coast) and with altitude (i.e. productivity gradients). We also assess the likelihood of interactions between guild members that may negatively impact vulnerable tundra species. Location North‐eastern part of Norway. Methods Extensive records of scavenger prevalence were obtained by deploying automatic digital cameras at experimental carcasses in tundra regions covering several thousand square kilometres and three winters in northern Norway. Main conclusions We found short‐range neighbourhood effects of forest and coast within the tundra scavenger guild. Species richness declined steeply with decreasing distance from the neighbouring ecosystems, in particular subarctic forest, and with increasing altitude. Bird species with strongholds in forest (golden eagle Aquila chrysaetos and hooded crow Corvus cornix) or along the coast (white‐tailed eagle Haliaeetus albicilla) were mostly responsible for short‐range neighbourhood effects on guild structure. However, the two most abundant guild members, the common raven Corvus corax and the red fox Vulpes vulpes, exhibited no spatial patterns within the range of neighbourhoods and altitudes examined. There was a clear diurnal segregation in the use of carcasses between birds and mammals reducing the likelihood of direct interactions between these two taxa. Presence of red fox appeared to exclude the arctic fox Vulpes lagopus, the only endemic tundra species within the guild, from carcasses.     

Mutualisms matter: pollination rate limits the distribution of oil‐secreting orchids

There are at least two immediate reasons why it is important to determine the role of biotic interactions, such as pollination, in limiting species distribution ranges. Firstly, if range limits are imposed by biotic factors, current and future distribution ranges might not be constrained by climate. Secondly, if biotic interactions limit the distribution ranges of species, anthropogenic impacts on these interactions are likely to have a major effect on biodiversity. Here we test the role of pollination in limiting plant distributions by studying plant community assembly in a guild of 15 oil‐secreting orchids (Coryciinae) along a pollination gradient. In all members of the guild, seed production depends on pollination by the oil‐collecting bee Rediviva peringueyi (Melittidae). While the mode of aboveground reproduction is uniform across the guild, the orchid species differ widely in their capacity for belowground clonal reproduction through the formation of bulbils, and hence span a range of predicted dependence on pollination (and subsequent seed set) for population persistence. Pollination rate by R. peringueyi varied across the landscape from 0 to 98% of flowers pollinated. With decreasing pollination, species richness of the orchid guild declined, and species were lost by the successive deletion of the least clonal species. Thus, pollination is shown to act as a biotic filter, excluding non‐clonal species from pollinator‐poor communities. The findings are consistent with the idea that pollination mutualisms matter ecologically by limiting the distribution of non‐clonal plants. Conversely, the results suggest that clonality allows some plant species to escape from the range of their pollinators.     

Analysis of trophic structure of two carnivore assemblages by means of guild identification

We evaluated the existence of trophic guild structure, considering seasonal and annual variation, in two terrestrial carnivore assemblages: one from Santa Cruz province (Argentinean Patagonia, composed by six carnivore species), and the other from Doñana National Park (SW Spain, composed by five carnivore species). To identify trophic guilds, we first studied seasonal and annual diets of predators, calculated trophic overlap among species pairs, and then constructed overlap matrices (similarity matrices). We determined guild membership objectively by entering the similarity matrices into the clustering technique unweighted pair-group method with arithmetic averaging. Carnivores from both assemblages were grouped, respectively, into four feeding guilds. Lagomorphs and rodents promoted the formation of two feeding guilds in both study sites, although the taxonomic composition of predator species that composed them was different. The ungulates-edentates feeding guild was only present at Santa Cruz, whereas the birds and reptiles feeding guild was only present at Doñana. Invertebrates and fruits were the base for the formation of a guild composed by species of the same taxonomic origin both in Santa Cruz and Doñana. Guild structure of Santa Cruz and Doñana assemblages did not exhibit seasonal or annual variation, although the specific guild composition changed over the two studied periods for both assemblages. This structure probably responded to discontinuities in resource spectra in Santa Cruz and fluctuations in rabbit abundance in Doñana. Our results support the hypothesis that establishes that guilds are originated by opportunistic convergence of species on abundant and energetically rewarding resources.     

Plant damage from and defenses against ‘cryptic’ herbivory: A guild perspective

Abstract

Despite considerable interest in the factors affecting trophic cascades in terrestrial systems, there has been relatively little attention paid to the importance of the herbivore-plant link in explaining why some systems “cascade” (have strong top-down effects on plant survival and population growth) and others “trickle” (have top-down effects on plant damage, but little effect on plant fitness). This is despite the fact that herbivore guild identity has long been recognized as a major force affecting herbivore-plant interactions. We address the potential importance of herbivore guild identity in determining the strength of tritrophic interactions by reviewing literature concerning plant damage from and induced defenses against two “cryptic” herbivore guilds, predispersal seed predators and root/stem borers. Although both guilds are capable of strongly affecting plant fitness, the impact of root/stem borers on plants in natural systems seems far greater than that of predispersal seed predators. The large impact of root/stem borers occurs via their disruption of plant vascular systems, while a variety of factors (safe-site-limited plant populations, long-lived seed banks, temporal plant escape, etc.) each seem important in explaining the smaller effect of predispersal seed predators. While the lack of attention to herbivore guilds is understandable, given the (by necessity) single-species focus of much trophic cascade research, we suggest that predator suppression of root/stem borers and predispersal seed predators will, respectively, yield strong versus weak top-down effects on plant fitness. The potential tritrophic consequences of herbivore feeding mode highlight the importance of research on varied predator-herbivore chains that share a common basal resource.     

Asymmetrical intraguild interactions with coyotes,red foxes,and domestic dogs may contribute to competitive exclusion of declining gray foxes

Species coexistence is governed by availability of resources and intraguild interactions including strategies to reduce ecological overlap. Gray foxes are dietary generalist mesopredators expected to benefit from anthropogenic disturbance, but populations have declined across the midwestern USA, including severe local extirpation rates coinciding with high coyote and domestic dog occurrence and low red fox occurrence. We used data from a large‐scale camera trap survey in southern Illinois, USA to quantify intraguild spatial and temporal interactions among the canid guild including domestic dogs. We used a two‐species co‐occurrence model to make pairwise assessments of conditional occupancy and detection rates. We also estimated temporal activity overlap among species and fit a fixed‐effects hierarchical community occupancy model with the four canid species. We partitioned the posterior distributions to compare gray fox occupancy probabilities conditional on estimated state of combinations of other species to assess support for hypothesized interactions. We found no evidence of broadscale avoidance among native canids and conclude that spatial and temporal segregation were limited by ubiquitous human disturbance. Mean guild richness was two canid species at a site and gray fox occupancy was greater when any combination of sympatric canids was also present, setting the stage for competitive exclusion over time. Domestic dogs may amplify competitive interactions by increasing canid guild size to the detriment of gray foxes. Our results suggest that while human activities can benefit some mesopredators, other species such as gray foxes may serve as bellwethers for habitat degradation with trophic downgrading and continued anthropogenic homogenization.     

Diets and trophic guilds of small fishes from coastal marine habitats in western Taiwan

The diets and trophic guilds of small fishes were examined along marine sandy beaches and in estuaries at depths <1·5 m in western Taiwan, Republic of China. Copepods were the most frequently identified item in fish guts, indicating they are key prey for the fish assemblages studied. Piscivore, crustacivore, detritivore, omnivore, zooplanktivore and terrestrial invertivore trophic guilds were identified. The zooplanktivore guild contained the most fish species. Maximum prey size consumption was positively correlated with standard length (L_S) in seven species and at the assemblage level and negatively correlated with L_S in a single detritivorous species. The diet data and trophic guild scheme produced by this study contribute to an understanding of coastal marine food webs and can inform ecosystem‐based fisheries management.     

Exploring co‐occurrence of closely‐related guild members in a fragmented landscape subject to rapid transformation

Quantifying biotic responses to landscape transformation is a major research focus. Most past studies have explored co‐occurrence of entire communities of a given group (e.g. birds) within largely intact ecosystems or over a limited time‐frame. By contrast, here we use data from a 15 yr experimental study, to explore intra‐guild co‐occurrence of six closely‐related and functionally‐similar sets of birds within 55 woodland fragments. Areas surrounding these remnants are undergoing transformation from grazed paddocks to Pinus radiata plantations, leading to a novel assemblage of forest and woodland birds. We sought to determine if the occurrence of a given species in a guild influenced the occurrence of other closely‐related species in that guild, and through this relationship whether there was evidence of co‐occurrence between species. After controlling for environmental and habitat variables which can affect species occurrence like time since commencement of landscape transformation, patch size and vegetation type, we found the occurrence of a given species was influenced by the occurrence of a closely‐related species in the same guild. Co‐occurrence varied among bird guilds and included: 1) positive co‐occurrence in which occurrence of one species within fragments positively affected the occurrence of another closely‐related guild member (e.g. eastern and crimson rosellas); and 2) negative co‐occurrence in which the occurrence of one species was negatively associated with the occurrence of another within the same guild (e.g. willie wagtail and grey fantail). We also identified interactions between patch size and species recording frequency within members of two guilds. For example, modelling of conditional recording frequency revealed the eastern rosella increased with increasing recordings of the crimson rosella in large patches, but decreased with increasing recordings of the crimson rosella in small patches. Our results provide empirical evidence of co‐occurrence among guild members and underscore the complexity of biotic responses to landscape transformation.     

Latitudinal extent and natural history characteristics of birds in Nicaragua

This paper assesses the latitudinal extent of terrestrial breeding birds in Nicaragua. In particular, associations among latitudinal midpoint, body mass, and latitudinal extent are examined; significant differences between natural history characteristics (trophic guild, forest dependence, number of forest types) and latitudinal extent are identified; and a test is undertaken of Rapoport's rule for birds at the edge of their northern or southern range in Nicaragua. Birds in Nicaragua were classified into four categories based on latitudinal extent: birds generally restricted to Central America (20%); birds near the edge of their range within Nicaragua (34%); Neotropical birds (42%); and Pan‐American birds (4%). Latitudinal midpoint had a significant negative correlation with latitudinal extent over different taxonomic scales. Natural history characteristics of trophic guild, forest dependence and number of forest types can account for significant differences in species latitudinal extent. Carnivores had greater latitudinal extents than most other trophic guilds, non‐forest birds had greater latitudinal extents than birds that require patchy forest, and birds that occur in four or more forest types had greater latitudinal extents than birds restricted to one or two forest types. Contrary to Rapoport's rule, birds with a northern affinity or latitudinal midpoint north of Nicaragua had significantly smaller latitudinal extents than birds with a southern affinity or latitudinal midpoint south of Nicaragua. A comparison of natural history characteristics of birds with northern and southern affinities found no difference between trophic guild or forest dependence but a significant difference among the number of forest types used by forest birds. Birds with a southern affinity were restricted to fewer forest types than birds with a northern affinity.