Habitat-related Variation Research Articles

A Sawback is a Sawback is a Sawback: Diet and Habitat-Related Variation in Body Size of the Turtle Graptemys oculifera Show It Is an Ecological Analogue of Its Two Closest Relatives

A Sawback is a Sawback is a Sawback: Diet and Habitat-Related Variation in Body Size of the Turtle Graptemys oculifera Show It Is an Ecological Analogue of Its Two Closest Relatives

Systematic revision of the Japanese freshwater snail

Semisulcospira is a freshwater snail genus highly divergent in the ancient Lake Biwa, Japan, with a history of ~4 million years. Although the shell morphology, karyotype and molecular phylogeny of the genus have been well studied, the systematic status of several non-monophyletic species remains uncertain. In this study, we have evaluated the taxonomic accounts of the species previously identified as Semisulcospira decipiens, S. habei and relatives. We examined the genetic relationships using genome-wide SNP data and elucidated morphological variation among these using Random Forest classification. Morphological relationships between the name-bearing type of S. decipiens and the newly collected specimens were also evaluated. Morphological characteristics effectively discriminated between the nine genetic clusters, and the correlation among morphology and substrates was elucidated. We revised taxonomic accounts of S. decipiens, S. habei, S. arenicola, S. nakasekoae and S. ourensis and synonymised S. multigranosa, S. habei yamaguchi, S. dilatata under S. decipiens and S. fluvialis under S. nakasekoae. We also described two new species, Semisulcospira elongata sp. nov. and Semisulcospira cryptica sp. nov., and redefined two phylogroups of the lacustrine species as the Semisulcospira niponica-group and the Semisulcospira nakasekoae-group. Traits of the species examined exhibiting intraspecific variation in the different substrates and flow velocity may indicate the morphological and trophic adaptations. The habitat-related variation has certainly caused the taxonomic confusion of the lacustrine species. Lake drainage contributes to increasing the species diversity of the genus, generating ecological isolation between the riverine and lacustrine habitats. ZooBank: urn:lsid:zoobank.org:pub:A83B99F4-8709-4295-86B3-A6C595D65DA0

Active acoustic telemetry reveals ontogenetic habitat-related variations in the coastal movement ecology of the white shark

BackgroundLittle is known about the fine-scale behavioural choices white sharks make. The assessment of movement at high spatio-temporal resolution can improve our understanding of behavioural patterns. Active acoustic telemetry was used along a coastal seascape of South Africa to investigate the movement-patterns of 19 white sharks tracked for 877 h within habitats known to host different prey types.ResultsA three-state hidden Markov model showed higher ontogenetic variability in the movements of white sharks around estuary-related coastal reef systems compared to around a pinniped colony. Our results further suggest white sharks (1) use the same searching strategy in areas where either pinnipeds or fishes are present; (2) occupy sub-tidal reef habitats possibly for either conserving energy or recovering energy spent hunting, and (3) travel directly between the other two states.ConclusionsWhite sharks appear not to simply roam coastal habitats, but rather adopt specific temporally optimized behaviours associated with distinct habitat features. The related behaviours are likely the result of a balance among ontogenetic experience, trophic niche, and energetics, aimed at maximizing the use of temporally and spatially heterogeneous environments and resources. The possible implications for the future conservation of white sharks in coastal areas are discussed, with particular attention to South Africa’s present conservation and management challenges.

Morphometric signals of population decline in diademed sifakas occupying degraded rainforest habitat in Madagascar

Anthropogenic habitat change can have varied impacts on primates, including both negative and positive outcomes. Even when behavioural shifts are seen, they may reflect decreased health, or simply behavioural flexibility; understanding this distinction is important for conservation efforts. This study examines habitat-related variation in adult and immature morphometrics among diademed sifakas (Propithecus diadema). We collected morphometric data from sifakas at Tsinjoarivo, Madagascar (19 years, 188 captures, 113 individuals). Captures spanned 12 groups, five within continuous forest (“CONT”), and seven in degraded fragments (“FRAG”) where sifakas have lower nutritional intakes. Few consistent differences were found between CONT and FRAG groups. However, using home range quality as a covariate rather than a CONT/FRAG dichotomy revealed a threshold: the two FRAG groups in the lowest-quality habitat showed low adult mass and condition (wasting), and low immature mass and length (stunting). Though less-disturbed fragments apparently provide viable habitat, we suggest the sifakas in the most challenging habitats cannot evolve fast enough to keep up with such rapid habitat change. We suggest other long-lived organisms will show similar morphometric “warning signs” (wasting in adults, stunting in immatures); selected morphometric variables can thus be useful at gauging vulnerability of populations in the face of anthropogenic change.

Assessing the ecological relevance of swimming performance traits: a case study of bluegill sunfish (Lepomis macrochirus)

A variety of fish species show habitat-related variation in traits associated with swimming performance and foraging behavior. This commonly manifests as a distinction between open water and shallow water littoral ecotypes. In bluegill sunfish (Lepomis macrochirus), open water fish exhibit greater energy economy and speed during sustained locomotion than those from the littoral, whereas littoral fish were more maneuverable than their open water counterparts. These distinctions are associated with variation in diet and foraging behavior and may represent a resource polyphenism that enhances fitness through more effective exploitation of particular habitat types. A lack of field data means that polyphenisms have not been placed in context with swimming behavior in the field. We have used 3D videography to quantify bluegill field swimming performance in open water and littoral habitats. This revealed patterns of performance variation that parallel the trait variation previously established in the laboratory. Open water fish utilized faster average swimming speeds than inshore fish, while indicators of nonlinearity and unsteadiness were greater in the littoral fish. There are, however, differences in propulsive behavior between the field and laboratory. Pectoral-fin-powered, median-paired fin swimming is rarely employed by open water fish. Field body-caudal fin swimming involves short sequences of propulsive tail beats interspersed with gliding, rather than the repeated propulsive cycles employed under steady-state conditions. This suggests a need to re-evaluate the applicability of steady-state performance traits to behavior and fitness in the field and highlights the general importance of obtaining field performance data.

Between-habitat variability in the population dynamics of a global marine invader may drive management uncertainty

Understanding population dynamics of established invasive species is important for designing effective management measures and predicting factors such as invasiveness and ecological impact. The kelp Undaria pinnatifida has spread to most temperate regions of the world, however a basic understanding of population dynamics is lacking for many regions. Here, Undaria was monitored for 2 years, at 9 sites, across 3 habitats to investigate habitat-related variation in population structure, reproductive capacity and morphology. Populations on marina pontoons were distinct from those in reef habitats, with extended recruitment periods and higher abundance, biomass, maturation rates and fecundity; potentially driven by lower inter-specific and higher intra-specific competition within marinas. This suggests that artificial habitats are likely to facilitate the spread, proliferation and reproductive fitness of Undaria across its non-native range. More broadly, generalising population dynamics of invasive species across habitat types is problematic, thus adding high complexity to management options.

Controls on foliar aluminium accumulation among populations of the tropical shrub Melastoma malabathricum L. (Melastomataceae).

Aluminium (Al) accumulation is a common trait expressed in at least 60 plant families and particularly prevalent in tropical woody plants. However, the functional significance and genetic or physiological controls on Al accumulation are currently unknown. We tested the hypothesis that differential expression of Al accumulation among wild populations of the Al-accumulating tropical shrub Melastoma malabathricum L. is associated with habitat-related variation in total and exchangeable soil Al concentrations. Mature leaves and seeds were sampled from 20 populations of M. malabathricum growing in six habitats across Peninsular Malaysia, and soil was collected from each site. The seeds were grown in hydroponic solutions comprising 50% Hoagland's solution amended with Al in the form of 1.0 mM AlCl3 to test the hypothesis that differential expression of foliar Al accumulation is an inherited trait. Foliar Al concentrations varied significantly among populations, but were not consistently different among plants growing in different habitats and showed no relationship to total or exchangeable Al concentrations in soils collected at the 20 sites. Mean foliar Al concentration in wild plants was positively correlated with foliar calcium (Ca) concentrations, and with total soil nitrogen (N), Ca and magnesium (Mg) concentrations, across the 20 populations, and Al addition increased foliar concentrations of phosphorus, Ca, Mg and potassium in seedlings. The differential expression of Al accumulation in M. malabathricum populations is uncoupled to local variation in soil Al concentrations, but may be sensitive to local soil-related variation in the availability of other macro-nutrients, in particular N, Ca and Mg. Further research on the factors controlling Al uptake should focus on the plasticity of this trait within populations of Al accumulators and interactions with micro-habitat variation in the availability of the macronutrient cations.

Habitat-related variation in composition of the essential oil of Seseli rigidum Waldst. & Kit. (Apiaceae)

Plant specialised metabolites like essential oils are highly variable depending on genetic and various ecological factors. The aim of the present work was to characterise essential oils of the species Seseli rigidum Waldst. & Kit. (Apiaceae) in various organs on the individual and populational levels. Geographical variability and the impact of climate and soil type on essential oil composition were also investigated. Individually sampled essential oils of roots, aerial parts and fruits of plants from seven populations were analysed by GC-FID and GC-MS. The investigated populations showed high interpopulational and especially intrapopulational variability of essential oil composition. In regard to the variability of essential oils, different chemotypes were defined. The essential oils of S. rigidum roots represented a falcarinol chemotype, oils of aerial parts constituted an α-pinene or α-pinene/sabinene chemotype and fruit essential oils can be characterised as belonging to a complex sabinene/α-pinene/β-phellandrene/falcarinol/germacrene B chemotype. At the species level, analysis of variance (ANOVA), principal component analysis (PCA) and canonical discriminant analysis (CDA) showed that the plant part exerted the strongest influence on the composition of essential oils. Climate had a high impact on composition of the essential oils of roots, aerial parts and fruits, while influence of the substrate was less pronounced. The variations in main compounds of essential oils based on climate or substrate were complex and specific to the plant part.

Differences in meiofauna communities with sediment depth are greater than habitat effects on the New Zealand continental margin: implications for vulnerability to anthropogenic disturbance.

Studies of deep-sea benthic communities have largely focused on particular (macro) habitats in isolation, with few studies considering multiple habitats simultaneously in a comparable manner. Compared to mega-epifauna and macrofauna, much less is known about habitat-related variation in meiofaunal community attributes (abundance, diversity and community structure). Here, we investigated meiofaunal community attributes in slope, canyon, seamount, and seep habitats in two regions on the continental slope of New Zealand (Hikurangi Margin and Bay of Plenty) at four water depths (700, 1,000, 1,200 and 1,500 m). We found that patterns were not the same for each community attribute. Significant differences in abundance were consistent across regions, habitats, water and sediment depths, while diversity and community structure only differed between sediment depths. Abundance was higher in canyon and seep habitats compared with other habitats, while between sediment layer, abundance and diversity were higher at the sediment surface. Our findings suggest that meiofaunal community attributes are affected by environmental factors that operate on micro- (cm) to meso- (0.1–10 km), and regional scales (> 100 km). We also found a weak, but significant, correlation between trawling intensity and surface sediment diversity. Overall, our results indicate that variability in meiofaunal communities was greater at small scale than at habitat or regional scale. These findings provide new insights into the factors controlling meiofauna in these deep-sea habitats and their potential vulnerability to anthropogenic activities.

Habitat-Related Variation in Body Size and Reproductive Output and an Examination of Reproductive Allometry in the Sabine Map Turtle (Graptemys sabinensis) across Three River Drainages

The Sabine Map Turtle (Graptemys sabinensis) inhabits the Sabine-Neches, Calcasieu, and Mermentau river drainages of southwestern Louisiana and east Texas. Sparse data in the literature mark it as having among the smallest body sizes and smallest clutch sizes among the 14 species of the genus Graptemys. All available data on life history originate from the upper Sabine and upper Calcasieu drainages, which are relatively high-gradient rivers with fast currents and numerous sandbars. Downstream segments of these drainages and the entire Mermentau drainage have almost no gradient, with little perceptible current and no sandbars. We sampled G. sabinensis from the Mermentau River and upper and lower portions of both the Sabine and Calcasieu drainages. We collected data on body size and radiographed gravid females in the lower Calcasieu and Mermentau drainages to examine clutch size and egg width and compared our data to literature records and measurements of museum specimens. Both males (to 104 mm in midline p...

Habitat-related phenotypic variation in adult Western Atlantic stone crabs (Menippe mercenaria Say, 1818) (Decapoda: Brachyura)

Habitat partitioning by different life stages or phenotypes in a heterogeneous marine environment could confer fitness advantages. Two distinct phenotypes of the Western Atlantic stone crab ( Menippe mercenaria Say, 1818), spotted and brown, are easily distinguishable and occupy different habitats in allopatry. Intermediate phenotypes occur in two geographic zones, the northeastern Gulf of Mexico and the southern Atlantic coast of the USA from South Carolina to northern Florida. We examined stone crab phenotypic variation and demography in two adjacent rivers near Charleston, SC, USA, the Kiawah and Stono rivers. The intertidal oyster habitat (quantified as reef per meter shoreline) in the Kiawah River is more than twice as dense as the oyster habitat in the Stono River. Significantly more brown than spotted crabs, a higher proportion of males, and larger individuals were collected in the Kiawah River in a year-long trapping study. Brown coloration for stone crabs on oyster reefs could confer a fitness advantage if these crabs are more cryptic than spotted crabs. The timing of ovigery and egg development did not differ between crabs in the Kiawah and Stono rivers or between brown and spotted stone crabs regardless of capture location. Males exhibited greater cheliped wear than females, but wear was unrelated to proximity to an oyster-reef habitat. Demographic patterns related to habitat use presented here are consistent with habitat use in the northeastern Gulf of Mexico zone of phenotypic variation. The differences in stone crab demographics in these two coastal rivers in South Carolina indicate that further studies are needed to determine whether this habitat-related phenotypic variation is representative of stone crab distributions throughout the South Atlantic Bight.

Marine lifestyle is associated with higher baseline corticosterone levels in birds

Because seawater is hyperosmotic relative to body fluids of most vertebrates, marine lifestyle is expected to strongly influence the physiology of marine tetrapods. Regulating the salt content of body fluids is energetically costly; and osmoregulatory organs may not totally overcome salt load and/or water loss. As a consequence, marine lifestyle should influence physiological systems involved in the maintenance of the physiological balance (homeostasis), in the mobilisation of energetic resources (e.g., to fuel salt excretion), or in the acquisition of resources (e.g., fresh water). Corticosterone (CORT) is one such ‘generalist’ mediator that is linked with energy expenditure, physiological stress and that activates osmoregulation. As a consequence, CORT is expected to be overall higher in marine tetrapods but this hypothesis has never been tested. Using comparative analyses, we tested this hypothesis in birds, a lineage for which available data on baseline CORT allow comparing marine versus terrestrial species, and species with or without salt glands. We found that marine species (and species with salt glands) display significantly higher baseline CORT during the wintering (but not the breeding) stage. Although salt glands’ presence was tightly linked to phylogeny, our results suggest that marine lifestyle may impose a strong, but overlooked, influence on the allostasis-related physiology of marine birds. Such habitat-related variation in physiology is a major phenomenon to explore owing to its general implications for understanding the physiological basis of evolutionary transitions in habitat use. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115, 154–161.

Habitat related variations in omega series of unsaturated fatty acids in Indian major Carp Cirrhinus mrigala

Atomic absorption spectrophotometery showed significant levels of contamination by Cd, Hg, Cu, Mn, Zn, Pb, Cr and Sn in fish habitats. Fatty acids from meat were detected by gas chromatography. C12:0, C20:0, C16:1(n-7), C16:1(n-9), C18:1(n-9), C20:1(n-9), C18:2(n-6), C18:4(n-3), C22:4(n-6), C20:5(n-3) and C22:4(n-6) fatty acids were found missing in fish obtained from area of higher pollution when compared to farmed fish.C16:1(n-7), C20:1(n-9), C20:2(n-6), C22:4(n-6) and C22:5(n-3) were found missing in the fish collected upstream to the areas of high intensity pollution. Loss of these important fatty acids indicates the sensitivity of the fish even in response to the lower intensity of pollution. Farmed fish showed optimal concentration of each fatty acid. Significant differences (p<0.05) were observed in fatty acid profiles of different species when each was compared in relation to their own habitats. Habitat of even lower intensity pollution confiscates fatty acids of omega series and lower down the

Spatial, temporal, and habitat-related variation in abundance of pelagic fishes in the Gulf of Mexico: potential implications of the deepwater horizon oil spill.

Time-series data collected over a four-year period were used to characterize patterns of abundance for pelagic fishes in the northern Gulf of Mexico (GoM) before (2007–2009) and after (2010) the Deepwater Horizon oil spill. Four numerically dominant pelagic species (blackfin tuna, blue marlin, dolphinfish, and sailfish) were included in our assessment, and larval density of each species was lower in 2010 than any of the three years prior to the oil spill, although larval abundance in 2010 was often statistically similar to other years surveyed. To assess potential overlap between suitable habitat of pelagic fish larvae and surface oil, generalized additive models (GAMs) were developed to evaluate the influence of ocean conditions on the abundance of larvae from 2007–2009. Explanatory variables from GAMs were then linked to environmental data from 2010 to predict the probability of occurrence for each species. The spatial extent of surface oil overlapped with early life habitat of each species, possibly indicating that the availability of high quality habitat was affected by the DH oil spill. Shifts in the distribution of spawning adults is another factor known to influence the abundance of larvae, and the spatial occurrence of a model pelagic predator (blue marlin) was characterized over the same four-year period using electronic tags. The spatial extent of oil coincided with areas used by adult blue marlin from 2007–2009, and the occurrence of blue marlin in areas impacted by the DH oil spill was lower in 2010 relative to pre-spill years.

Lineage-specific molecular probing reveals novel diversity and ecological partitioning of haplosporidians

Haplosporidians are rhizarian parasites of mostly marine invertebrates. They include the causative agents of diseases of commercially important molluscs, including MSX disease in oysters. Despite their importance for food security, their diversity and distributions are poorly known. We used a combination of group-specific PCR primers to probe environmental DNA samples from planktonic and benthic environments in Europe, South Africa and Panama. This revealed several highly distinct novel clades, novel lineages within known clades and seasonal (spring vs autumn) and habitat-related (brackish vs littoral) variation in assemblage composition. High frequencies of haplosporidian lineages in the water column provide the first evidence for life cycles involving planktonic hosts, host-free stages or both. The general absence of haplosporidian lineages from all large online sequence data sets emphasises the importance of lineage-specific approaches for studying these highly divergent and diverse lineages. Combined with host-based field surveys, environmental sampling for pathogens will enhance future detection of known and novel pathogens and the assessment of disease risk.

Habitat-related variation in seedling recruitment of Gentiana pannonica

Differences in seedling recruitment of Gentiana pannonica were investigated between the primary (relict) and the secondary (semi-natural) forest-free habitats of the Bohemian Forest (870–1200 m a.s.l.) and of the Alps (1045–1935 m a.s.l.) to understand the factors promoting the seedling recruitment of G. pannonica and their importance for species distribution, population structure, and conservation. In the communities with adult plants of G. pannonica, we recorded environmental variables (the slope, the altitude, and the covers of bare ground, litter, and rocks), estimated parameters of the vegetation (the covers of herbs, bryophytes, and dwarf shrubs), and counted the seedlings of G. pannonica. In a field experiment, we investigated seedling survival under different soil moisture regimes. We also observed seasonal dynamics of seedling recruitment in permanent plots over the course of three years. In the primary habitats of both regions, G. pannonica grew in a relatively wide range of communities, and its seedlings occurred in each area. In the secondary habitats of the Bohemian Forest, a very low frequency of the seedlings was recorded. The number of seedlings increased with the covers of the moss layer and of bare soil and decreased with the cover of the herb layer, especially of graminoids. The seedling mortality was significantly lower in the plots with higher soil moistures, and the emergence of new-born seedlings was concentrated in the spring season, when the soil received a high water supply due to melting of snow. For the successful generative reproduction of G. pannonica, our findings highlight the critical importance of the microsites with low levels of competition and of sufficient soil moisture G. pannonica. It seems that because of the long-term lack of grazing disturbances, the structures of the secondary habitats of G. pannonica in the Bohemian Forest have become unfavourable for seedling establishment and generative reproduction of this threatened species.

Spatial, temporal and ontogenetic variation in the association of fishes (family Labridae) with rocky-reef habitats

Habitat variability is an important factor structuring fish assemblages of rocky reefs in temperate Australia. Accepting the generality of this model requires that habitat-related variation is consistent through time, across multiple spatial scales, and applies to all life-history stages. We used repeated underwater visual surveys at multiple spatial scales over a 22-month period to test whether three distinct rocky-reef habitats had different wrasse assemblages and whether these assemblages were subject to spatial, temporal and ontogenetic variability. Overall, the strongest and most consistent habitat association was with sponge gardens, which had the most distinct assemblage, and the greatest species richness and density of individuals. Habitat associations in fringe and barrens were less consistent. A substantial increase in the abundance of small individuals, coinciding with warmer sea temperatures, contributed to temporal fluctuations in the density of wrasses. Overall, habitats were not strongly partitioned among larger individuals of the most abundant species, suggesting that adults are largely habitat generalists whereas small, recruiting individuals showed greater habitat specialisation. The present study emphasises the importance of incorporating spatial, temporal and ontogenetic variability into surveys of fish assemblages to understand more fully the dynamics of temperate rocky-reef systems.

Egg Size Variation in Blue TitsCyanistes caeruleusand Great TitsParus majorin Relation to Habitat Differences in Snail Abundance

Wild passerines, especially tits, utilize snail shells as the main source of calcium necessary for laying females to construct egg shells. This research found that the two study areas, representing two habitat types — a mature decid- uous forest and a human-disturbed parkland — are inhabited by different snail assemblages: both species richness and density are much higher in the parkland than in the forest. This means that less calcium is available to female tits in the forest than in the parkland, which could result in calcium limitation in the former habitat. Egg size traits, i.e. volume, length and breadth, in the Blue Tit show a consistent long-term pattern of variation that reflects the pattern of calcium availability: egg trait values are higher in the parkland than in the woodland. No habitat-related variation in egg size traits was found in the Great Tits. We suggest that the lack of a relation between Great Tit egg characteristics and snail availability results from the higher ecological plasticity of this species in comparison with the Blue Tit, including its abil- ity to exploit alternative sources of calcium.

Habitat-related birdsong divergence: a multi-level study on the influence of territory density and ambient noise in European blackbirds

Song plays an important role in avian communication and acoustic variation is important at both the individual and population level. Habitat-related variation between populations in particular can reflect adaptations to the environment accumulated over generations, but this may not always be the case. In this study, we test whether variation between individuals matches local conditions with respect to noise level and territory density to examine whether short-term flexibility could contribute to song divergence at the population level. We conducted a case study on an urban and forest population of the European blackbird and show divergence at the population level (i.e. across habitats) in blackbird song, anthropogenic noise level and territory density. Unlike in several other species, we found a lack of any correlation at the individual level (i.e. across individuals) between song features and ambient noise. This suggests species-specific causal explanations for noise-dependent song differentiation which are likely associated with variation in song-copying behaviour or feedback constraints related to variable singing styles. On the other hand, we found that at the level of individual territories, temporal features, but not spectral ones, are correlated to territory density and seasonality. This suggests that short-term individual variation can indeed contribute to habitat-dependent divergence at the population level. As this may undermine the potential role for song as a population marker, we conclude that more investigations on individual song flexibility are required for a better understanding of the impact of population-level song divergence on hybridisation and speciation.

Forest management and temporal effects on food abundance for a ground-foraging bird ( Catharus guttatus)

While food abundance is known to limit bird populations, few studies have simultaneously examined both temporal and habitat-related variation in food abundance for ground-foraging birds. We surveyed ground-dwelling arthropods throughout the breeding season and in three forest harvest types (clearcut, selection, and shelterwood stands managed for spruce, fir and hemlock) at the Penobscot Experimental Forest (PEF), Bradley, Maine, USA. Pitfall trapping during 2003 and 2004 was used to measure seasonal and habitat-related variation in abundance of ground-dwelling arthropod food items for hermit thrushes. Arthropods were sorted into relevant taxonomic and size class categories based on the known diet of hermit thrushes. Habitat variables included forest management type, stand-level structure and composition of tree species, and microhabitat measures in a 1 m 2 area around the pitfall traps. We used redundancy analysis to find stand-level and microhabitat measures that best explained variation in arthropod abundance during 2004. The majority of arthropod captures comprised three groups: ants (Formicidae, 44%), ground beetles (Carabidae, 13%), and spiders (Araneae, 11%). There was significant temporal variation in captures for many taxa. Notably, there were as many as six times more Araneae in early compared to late season samples suggesting the importance of Araneae to ground-foraging birds. Carabidae were more abundant in selection versus either shelterwood or clearcut stands on one sample date. Conversely, Formicidae and Curculionidae were more abundant in shelterwood plots on one and three sampling dates, respectively. Overall, our data provided little evidence that forest management type impacts arthropod food abundance, in stands 5–20 years post-harvest. Abundance of Carabidae was positively correlated with the number of softwoods less than 5 cm DBH and the number of hardwoods greater than 10 cm DBH, while abundance of Formicidae and Homopterans was negatively associated with these same measures. Several taxa were negatively associated with percent of the 1 m 2 around the pitfall that was shaded, including Araneae, Carabidae, Formicidae, and Staphylinidae. These results suggest that less-shaded forest microhabitats are important areas of increased food abundance for ground-foraging birds, regardless of forest management type or tree composition. Consequently, forest managers seeking to maximize food abundance for ground-foraging birds in managed spruce-fir forests should consider retaining some large diameter hardwood trees and use management techniques that reduce forest floor shading.