Partial diel vertical migrations in pelagic fish

1. Field studies on diel vertical migration (DVM) usually report uniform behaviour with population-wide ascents and descents during crepuscular periods. This contrasts partial seasonal migrations of many animal populations, where individuals choose either the resident or the migrant strategy depending on population density, feeding opportunity and predation risk in the resident and migrant habitats. 2. We tested whether DVM of freshwater zooplanktivorous fish (Coregonus spp.) resembles partial migrations. Twenty-eight hydroacoustic surveys were performed in the deep Lake Stechlin (Germany) between 2000 and 2010, with samplings encompassing all months between March and December. Zooplankton samples were simultaneously taken in epilimnetic and hypolimnetic layers. Fish obtained from depth-stratified samplings by a midwater trawl were used to test for individual differences between residents and migrants. 3. We show for the first time that DVMs of freshwater fish resemble patterns of partial migrations often found in seasonal environments. Across all samplings, 7-33% of fish did not ascend at dusk, but exhibited the resident strategy. The proportion or residents increased at low zooplankton feeding rates in the daytime habitat and during months when the temperature difference between daytime and night-time habitats was minor. 4. Slightly larger size and higher caloric density of migrants over residents in one of the coexisting Coregonus species suggested that individual differences contributed to the migration strategy performed. However, these results were based on one sample only, and extrapolation to the entire data set is not possible. 5. Our results are indirect evidence that the balance between migrants and residents may primarily depend on the trade-off between feeding gains and metabolic and predation costs of migration. However, the results also suggest that the global fitness consequences for the resident and migrant strategies may not be identical, rendering the importance of individual traits in the 'decision to migrate' likely.     

Distinguishing between juvenile anadromous and resident brook trout (Salvelinus fontinalis) using morphology

Phenotypic variation linked to habitat use has been observed in fish, both between and within species. In many river systems, migratory and resident forms of salmonids coexist, including anadromous (migrant) and resident brook trout, Salvelinus fontinalis. In such populations, juvenile anadromous (migrant) brook trout, prior to migration, inhabit regions of higher current velocity than residents. Because it is more costly to occupy fast currents than slow currents, differences in morphology minimizing the effects of drag were expected between the two forms. As predicted, migrant brook trout were found to be more streamlined (narrower and shallower bodies) than resident brook trout, and these differences persisted into the marine life of the fish. Migrants also exhibited shorter pectoral fins, which facilitate pelagic swimming, indicating that migrants, prior to their migration to the sea, possess the appropriate morphology for swimming in open water habitats. The reported differences between migrants and residents were powerful enough to derive discriminant functions, using only five of the seven measured traits, allowing for accurate classification of brook trout as either migrants or residents with an overall correct classification rate of 87%. Importantly, this study contributes to the notion that a link exists between morphology, habitat use, metabolic costs and life-history strategies. Contribution to the program of CIRSA (Centre Interuniversitaire de Recherche sur le Saumon Atlantique).     

Effects of habitat,season, and age on winter fat storage by migrant and resident birds in Jamaica

Most small birds wintering in the tropics should show little subcutaneous fat deposition (SFD), except in habitats where food availability may decline in late winter or, for some resident species, to prepare for incubation or brooding fasts. However, these predictions need re‐examination in light of a new, precise, cross‐validated method to compare SFD among habitats and species. We sampled 170 Nearctic‐Neotropical migrant and 279 resident birds during early and late winter in 1993 and 1994 in Jamaica, West Indies. Habitats, from greatest to least expected availability of insect prey, were (1) mangrove forest, (2) montane/foothills forest and cultivation, (3) dry limestone forest, and (4) acacia scrub. Percent lipid, estimated from multiple‐regression models using visual fat scoring (0–8 scale), total‐body electrical conductivity, and a variety of morphometrics, was categorized by percentile ranks to determine if SFD varied by habitat, season, or age for all species, resident species, migrant species, and several individual species. SFD averaged ~ 13% total mass for all birds, ranging from 8–24% for well‐sampled species. The few bird species in acacia scrub, primarily two facultative long‐distance migrants, averaged ~ 26% lipid content, significantly more than birds in other habitats. Most birds did not vary in SFD in the other three habitats, although Common Yellowthroats (Geothlypis trichas) had greater SFD in dry limestone habitat than in montane habitat. Bananaquits (Coereba flaveola) and Jamaican Euphonias (Euphonia jamaica) in montane habitat, especially in early winter, had higher SFD than other resident species. Contrary to our prediction, adults and juveniles had similar SFD, with the exception of juveniles having more SFD than adults in acacia scrub habitat. Winter fat deposition (or, in some cases, muscle‐protein catabolism) in the tropics may be an overlooked strategy, potentially important as a hedge against fasting for floaters, facultative migrants, some territorial migrants in habitats with seasonal declines in food resources, and some resident species prior to breeding.     

Nitrogen fixation and nitrogen limitation of primary production along a natural marsh chronosequence

We experimentally tested the conditions where heterospecific attraction is more likely to occur. The heterospecific attraction hypothesis predicts that colonizing or migrant individuals use the presence of resident species as a cue for profitable breeding sites. In other words, increasing resident densities will result in increased migrant densities until the costs of interspecific competition override the benefits of heterospecific attraction. The experiment consisted of a reference and a manipulation year. In the reference year, resident titmice were permitted to breed at intermediate densities whilst in the manipulation year, resident densities were manipulated in nine study plots. Three treatments were performed as low, intermediate and high resident densities and migrant density responses were measured in both years. Relative between-year migrant and resident densities were analyzed by regression analysis. Migrant foliage gleaning guild densities responded linearly and positively, as did densities of habitat generalists, in particular Chaffinch ( Fringilla coelebs),. The ground-foraging guild did not show a response. This study provides support for predictions of the heterospecific attraction hypothesis and suggests that information on habitat quality with reference to both food availability and safe breeding sites are important in using heterospecifics as cues. Based on Chaffinch response data, artificially increased resident densities were not high enough for competitive effects between residents and migrants to decrease heterospecific attraction. It seems unlikely that in northern environments natural resident densities will reach high levels where competitive effects would occur, therefore heterospecific attraction will always be beneficial. This study again shows the importance of heterospecific attraction in migrant habitat selection and as a process promoting species diversity in northern breeding bird assemblages.     

Consequences of the settlement of migrant European Robins Erithacus rubecula in wintering habitats occupied by conspecific residents

In wintering areas where migrant birds meet sedentary conspecifics, early settlement of local residents in the best habitat patches might reduce the availability of suitable sites for arriving migrants. We studied how sympatric migratory and sedentary European Robins Erithacus rubecula occupy two wintering habitats of different quality (forests and shrublands) in southern Spain, and how such a distribution affects individuals of each population sector. In September, before migrants arrived, Robins were only found in forests, and they had already saturated these habitats, so that rather than increasing Robin abundance in these habitats, the arrival of migrants caused a massive occupation of the previously vacant shrublands. During the winter, we captured Robins and identified them as migrants or residents using a discriminant function based on morphological traits. Residents always predominated in forests, and migrants in shrublands, but through the winter around 35% of residents (mainly juveniles) moved to shrublands, having been replaced by some migrants in forests. Although food was more abundant in shrublands, Robins had better body condition in forests, suggesting that other factors determined habitat preferences (e.g. shelter availability or food diversity, which were higher in forests). In addition, we observed a greater variance in body mass relative to body size in forests, suggesting that energy management was less constrained in this habitat (for example owing to a lower exposure to predators or a higher food predictability). Our results suggest that sedentary Robins benefit from an early occupation of the best habitats in the wintering grounds, forcing migrants to colonize apparently less suitable sites. This would explain the persistence of these small southern populations despite the yearly flooding of the area by huge numbers of migrant conspecifics.     

Heterospecific attraction and food resources in migrants' breeding patch selection in northern boreal forest

We studied experimentally how heterospecific attraction may affect habitat selection of migrant passerine birds in Finnish Lapland. We manipulated the densities of resident tit species (Parus spp.). In four study plots residents were removed before the arrival of the migrants in the first study year, and in four other plots their densities were increased by releasing caught individuals. In the second year the treatments of the areas were reversed, allowing paired comparisons within each plot. We also investigated the relative abundance of arthropods in the study plots by the sweep-net method. This allowed us to estimate the effect of food resources on the abundance of birds. The heterospecific attraction hypothesis predicts that densities of migrant species (especially habitat generalists) would be higher during increased resident density. Results supported this prediction. Densities and number of the most abundant migrant species were significantly higher when resident density was increased than when they were removed. On the species level the redwing (Turdus iliacus) showed the strongest positive response to the increased abundance of tits. Migrant bird abundances seemed not to vary in parallel with relative arthropod abundance, with the exception of the pied flycatcher (Ficedula hypoleuca) which showed a strongly positive correlation with many arthropod groups. The results of the experiment indicate that migrants can use resident tit species as a cue to a profitable breeding patch. The relationship between the abundance of the birds and arthropods suggests that annual changes in food resources during the breeding season probably do not have a very important effect on bird populations in these areas. The results stress the importance of positive interspecific interactions in structuring northern breeding bird communities. Received: 1 September 1997 / Accepted: 22 January 1998     

Migration patterns and functional groups of spiders in a desert agroecosystem

Abstract 1. Arthropods living in annual crops suffer mortality caused by agricultural practices. Therefore, migration from surrounding habitats is crucial to maintain populations of natural enemies of insect pests in crops. In desert agroecosystems there is a pronounced contrast between managed and unmanaged habitats, where irrigated and fertilised crops are islands of productivity in an arid matrix. This contrast could either enhance or inhibit movement of natural enemies between the landscape components. 2. The importance of the surrounding arid habitats as a source for spiders in crops was examined in the Negev desert of Israel. Spiders were sampled in both arid natural habitat and adjacent wheat fields using pitfall traps and visual searching. In addition, spiders in wheat fields were sampled throughout the winter cropping season using emergence traps at increasing distances from the field edge. Stationary and movable emergence traps were used to distinguish between residents and migrant species. 3. The spider assemblage in the wheat was dominated by three families: Linyphiidae, Theridiidae, and Gnaphosidae. Spider sampling in both natural arid habitat and adjacent wheat fields enabled four functional groups to be recognised that differed in habitat preference, movement patterns, and population dynamics. Thirty‐three per cent of collected individuals were classified as crop residents whereas more than 50% were classified as migrants from the surrounding habitats. These findings suggest that the surrounding habitats influence spider assemblage composition in the fields, in spite of the marked contrast in habitat structure and productivity. 4. Spider assemblages in the wheat fields were dominated by migrant species arriving from the surrounding arid habitats. Migrant spiders inhabited the crop throughout the cropping season. The combined contribution of resident and migrant functional groups may act to prevent insect pest outbreaks in this desert agroecosystem.     

Densities and population estimates of breeding Skylarks Alauda arvensis in Britain in 1997

We present the results of a national survey of breeding Skylarks Alauda arvensis in Britain in 1997 carried out by the British Trust for Ornithology (BTO). Numbers of Skylarks and land-use types were recorded by volunteers in 608 1-km squares, selected using random stratification based on the Institute of Terrestrial Ecology's (ITE) Landscape Classification to avoid over- or under-sampling particular habitat types. The results suggest a maximum national population of around 1000 000 pairs. This agrees extremely well with the national population estimate of around 1046 000 pairs derived from the Breeding Bird Survey (BBS) of the BTO/Joint Nature Conservation Committee/Royal Society for the Protection of Birds, and provides further evidence for the robustness of the BBS as a national monitoring scheme for common and widespread species. The figure is approximately half that of the most recent published estimate of 2000 000 in 1988–91. However, the scale of this discrepancy is likely to reflect a bias in Atlas field methodology and site selection since there has been a real decline of approximately 9% since 1990. Arable squares supported the highest densities of Skylarks; 4.6–6.0 pairs per km², and 46–49% of the British breeding population was associated with arable areas. Marginal upland and upland areas supported lower densities but still accounted for approximately 34% of the estimated national breeding population. Differences in density at broad habitat scales were reflected in geographical differences across Britain, with southern and eastern arable regions supporting much higher densities than western and northern ones. At a finer scale, Skylarks occurred at highest densities on, and showed highest habitat preferences for, set-aside and various types of ungrazed grassland. Winter cereal, improved grassland and set-aside held the highest proportion of the Skylark population on farmland in England and Wales; grazed pasture, winter cereals and spring cereals held the highest proportion in Scotland.     

A field reciprocal transplant experiment reveals asymmetric costs of migration between lake and river ecotypes of three‐spined sticklebacks (Gasterosteus aculeatus)

Theory of local adaptation predicts that nonadapted migrants will suffer increased costs compared to local residents. Ultimately this process can result in the reduction of gene flow and culminate in speciation. Here, we experimentally investigated the relative fitness of migrants in foreign habitats, focusing on diverging lake and river ecotypes of three‐spined sticklebacks. A reciprocal transplant experiment performed in the field revealed asymmetric costs of migration: whereas mortality of river fish was increased under lake conditions, lake migrants suffered from reduced growth relative to river residents. Selection against migrants thus involved different traits in each habitat but generally contributed to bidirectional reduction in gene flow. Focusing particularly on the parasitic environments, migrant fish differed from resident fish in the parasite community they harboured. This pattern correlated with both cellular phenotypes of innate immunity as well as with allelic variation at the genes of the major histocompatibility complex. In addition to showing the costs of migration in three‐spined sticklebacks, this study highlights the role of asymmetric selection particularly from parasitism in genotype sorting and in the emergence of local adaptation.     

Avian population consequences of climate change are most severe for long-distance migrants in seasonal habitats

One consequence of climate change is an increasing mismatch between timing of food requirements and food availability. Such a mismatch is primarily expected in avian long-distance migrants because of their complex annual cycle, and in habitats with a seasonal food peak. Here we show that insectivorous long-distance migrant species in The Netherlands declined strongly (1984–2004) in forests, a habitat characterized by a short spring food peak, but that they did not decline in less seasonal marshes. Also, within generalist long-distance migrant species, populations declined more strongly in forests than in marshes. Forest-inhabiting migrant species arriving latest in spring declined most sharply, probably because their mismatch with the peak in food supply is greatest. Residents and short-distance migrants had non-declining populations in both habitats, suggesting that habitat quality did not deteriorate. Habitat-related differences in trends were most probably caused by climate change because at a European scale, long-distance migrants in forests declined more severely in western Europe, where springs have become considerably warmer, when compared with northern Europe, where temperatures during spring arrival and breeding have increased less. Our results suggest that trophic mismatches may have become a major cause for population declines in long-distance migrants in highly seasonal habitats.     

Habitat use,abundance, and persistence of Neotropical migrant birds in a habitat matrix in northeast Belize

ABSTRACT To ensure adequate protection of nonbreeding habitats used by Neotropical migratory landbirds, we must first address questions about habitat use and quality. On the Yucatan peninsula, migrants use many habitats, several of which remain unstudied, and methodological differences preclude interhabitat comparisons based on studies to date. We used distance sampling along line transects in six habitats in northeast Belize to examine use of previously unstudied habitats (e.g., salt marsh) by Neotropical migrants and to permit comparison across habitats. We calculated unadjusted and adjusted (for detectability) density estimates for individual migrant species and for all species combined to generate hypotheses about habitat quality based on the assumption that density and quality are positively correlated. Adjusted density estimates for all migrants were highest in black mangrove habitat (1799 ± 110 ind/km²), intermediate in three forest types and milpa (range 598–802 ind/km²), and lowest in salt marsh (207 ± 32.3 ind/km²). By combining density estimates with habitat availability in our study region, we estimated that evergreen forest and black mangrove supported 70% and 9% of the region's migrant population, respectively. At the species level, five of the 10 most common species had habitat preferences (>50% detections in one habitat). Given the diversity of habitat preferences among species and apparent seasonal movements, our results indicate that Neotropical migrants in northeast Belize are dependent on a matrix of interconnected habitats.     

Why do migrants move downhill? The effects of increasing predation and density on red deer altitudinal migration in temperate Carpathian forests

Resource selection by ungulates is driven by trade-offs between foraging and predation avoidance or by intraspecific competition. Ungulates use migratory flexibility to optimize access to spatially and temporally variable resources across seasons, sometimes even adaptively switching between migrant and resident strategy as conditions change. After an 80% increase in red deer (Cervus elaphus) population and simultaneous recovery of wolves (Canis lupus) in the Kremnica Mountains, Slovakia, a significant portion of the deer population started to migrate downhill (<?700 m) to marginal habitats during winter. Building on available spatial data on forage availability, predation risk, and deer abundance, we tested for differences in habitat selection of migrant and resident male red deer to assess possible reasons for this change. On high-altitude (700–1100 m) summer ranges, deer were not forced to trade-off forage to avoid predation within their home ranges. However, during winter, residents remaining on high-altitude ranges selected for areas with highly abundant forage only under low predation risk or at high deer abundance. Downhill migration exposed migrants to 15% lower forage availability but simultaneously reduced wolf predation risk by 39% relative to residents. Consequently, the limited access to forage resources at low-altitude ranges have reduced antler growth, especially in young males. Our study represents one of few that address the role of predation risk in driving seasonal migrations in temperate systems where snow is not likely to be the major driver of migration to low-altitude winter ranges.     

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.     

Density‐dependent habitat selection predicts fitness and abundance in a small lizard

Density‐dependent habitat selection has been used to predict and explain patterns of abundance of species between habitats. Thermal quality, a density‐independent component of habitat suitability, is often the most important factor for habitat selection in ectotherms which comprise the vast majority of animal species. Ectotherms may reach high densities such that individual fitness is reduced in a habitat due to increased competition for finite resources. Therefore, density and thermal quality may present conflicting information about which habitat will provide the highest fitness reward and ectotherm habitat selection may be density‐independent. Using ornate tree lizards Urosaurus ornatus at 10 sites each straddling two adjacent habitats (wash and upland), we tested the hypothesis that habitat selection is density‐dependent even when thermal quality differs between habitats. We first tested that fitness proxies decline with density in each habitat, indicating density‐dependent effects on habitat suitability. We also confirmed that the two habitats vary in suitability (quantified by food abundance and thermal quality). Next, we tested the predictions that habitat selection depends on density with isodar analyses and that fitness proxies are equal in the two habitats within a site. We found that monthly survival rates decreased with density, and that the wash habitat had more prey and higher thermal quality than the upland habitat. Lizards preferred the habitat with more food and higher thermal quality, lizard densities in the two habitats were positively correlated, and fitness proxies of lizards did not differ between habitats. These patterns are consistent with density‐dependent habitat selection, despite differences in thermal quality between habitats. We expect that density‐dependent habitat selection is widespread in terrestrial ectotherms when densities are high and temperatures are close to their optimal performance range. In areas where thermal quality is low, however, we expect that depletable resources, such as food, become less limiting because assimilating resources is more difficult.     

A comparison of sex ratio,birth periods and calf survival among Serengeti wildebeest sub‐populations,Tanzania

Although adaptation and environmental conditions can easily predict demographic variation in most savannah ungulates, no study on demographic consequences arising from natural and anthropogenic factors among Serengeti wildebeest (Connochaetes taurinus) sub‐populations in Tanzania has been carried out. Here, I report estimates of annual sex ratio, calf and yearling survival rate and birth seasonality between resident and migratory sub‐populations to explore demographic patterns arising from the different age and sex structure. The results indicate significantly higher female‐biased sex ratios in the resident and almost even sex ratios among individual migrants. The calf recruitment estimated as mother: offspring ratios indicate a more synchronous birth in the migrant than the resident sub‐population. Also, birth seasonality in the migratory sub‐population coincided with seasonal variability of rainfall and the timing of the birth peak was more variable in the migrants than the resident sub‐population. The migratory sub‐population had a higher annual proportional mean calf survival estimate (0.84) than that of the residents (0.44) probably due to higher mortality resulting from predation in the western corridor. However, the proportion of yearling survival estimates was much lower (0.31) in the migrants and relatively higher (0.39) in the residents. Different demographic outcomes resulting from environment, predation, movements and ecological factors including resource competition have conservation implications for the two sub‐populations.     

Perspectives on Palaearctic and Nearctic bird migration; comparisons and overview of life-history and ecology of migrant passerines

In this paper we compare ecological attributes of tropical migrant passerines from the Nearctic and western Palaearctic, focusing particularly on habitat association patterns during both breeding and wintering seasons. Three regions were compared: Europe, western and eastern North America. Breeding bird census data from 32 studies (each including at least four stages of forest succession) were used to assess the association patterns of breeding habitats among tropical migrants. For each species we calculated an index of habitat diversity and habitat preference.
Tropical migrants preferred earlier successional stages than other birds in Europe. The opposite was true in eastern North America. In eastern North America, tropical migrants tended to be associated with a smaller range of serai stages than other passerine species. In their winter quarters, Palaearctic migrants live primarily in open habitats, such as savannas, whereas eastern Nearctic migrants make more frequent use of evergreen forests. Migrants from western North America show the greatest match between breeding and wintering habitats.
We relate the results to the taxonomy and probable history of contemporary avifaunas and vegetation formations of the Old and New World. Taxonomically, tropical migrants from different parts of the Holarctic are less closely related to each other than residents and short-distance migrants. Tropical and temperate avifaunas are more closely related to each other in the New World than in the Old World. Conservation implications of the between-continent differences are briefly discussed.     

A preliminary assessment of the habitat selection of two Palaearctic migrant passerine species in West Africa

We investigated the habitat selected by two Palaearctic migrants (Pied Flycatcher, Ficedula hypoleuca, Willow Warbler, Phylloscopus trochilus) in a patchy landscape in Ivory Coast and compared it with the habitat selection of Afrotropical species in the same foraging guilds. Transect counts were used to test the hypothesis that migrants use more open and more seasonal habitats and have a broader use of habitats compared with resident species. Habitats compared were, in order of decreasing tree density, gallery forest, an isolated forest and bush/tree savanna. The isolated forest had the most pronounced seasonal changes (deciduous trees) and was the one with the most diverse vegetation structure. The habitat where both migrants were most frequent was the isolated forest, and thus occurred in the habitat with the most pronounced seasonal change. Diversity of habitats selected was highest in migrants but in the Pied Flycatcher this was possibly an artefact due to subdominant individuals being excluded from the preferred habitat by territorial birds. Potential competition for habitat with Afrotropical species was found to be low.     

The development of regular seasonal habitat shifts in a landlocked Arctic charr, Salvelinus alpinus L., population

Parts of the Arctic charr population of the subarctic Lake Visjön in north-west Sweden migrate upstream during the spring to two small, recently eutrophied and very productive lakes. Large repeat migrants arrive first, followed by young first-time migrants. Charr in the small lakes grow more rapidly than those resident in L. Visjön. In early September mature fish leave the lakes, followed by immature fish later in September and in October. Overwintering and spawning takes place in L. Visjön. Migratory females attain maturity at age 4 years and resident females at age 6 years. The migrant fish return annually until they are 5–6 years old. This limit may be due to reduced relative growth benefits of the habitat shift for larger individuals. The rapid development of these regular habitat shifts could be explained by an internally fixed exploratory behaviour in these Arctic charr that makes the detection and utilization of distant feeding resources possible. Migrants will possess a considerably higher fitness, if survival rates for migratory and resident fish are equal.     

Factors affecting songbird communities using new short rotation coppice habitats in spring

The aim of this study was to describe the songbird communities occupying willow and poplar short rotation coppice (SRC) crops during the breeding season, and to identify the features of existing plantations that affect their abundance. Songbird point-counts were undertaken at 66 different plots of SRC at 29 sites throughout Britain and Ireland during spring 1993. Measures of vegetation and coppice management in each plot were also taken. The songbird species using the SRC survey plots were similar to those reported from traditional coppice habitats. Willow SRC contained more resident and migrant songbird species than poplar SRC. Warbler species and buntings in particular were rarely recorded from poplar plots. Finches, tits and thrushes were recorded equally from both willow and poplar. More migrant species were recorded from year 2 willow coppice (i.e. in its third growth season since winter cutting) than in either year 1 or year 3. Most resident species selected older willow or poplar coppice growth up to year 3 or 4, the oldest age classes in the sample. These 4-year trends for migrant and resident songbirds are similar to those observed in traditional coppice woodland over a 10- or 12-year rotation. Skylark and Meadow Pipit were recorded from recently cut SRC plots (year 0). In a regression analysis, the number of songbird species and individuals, particularly migrants, were found to be positively related to the increased structural density or complexity of the coppice vegetation.     

Resident and transient coyotes exhibit differential patterns of movement behavior across heterogeneous landscapes in the southeastern United States

Coyotes (Canis latrans) are a highly adaptable canid species whose behavioral plasticity has allowed them to persist in a wide array of habitats throughout North America. As generalists, coyotes can alter movement patterns and change territorial strategies between residency (high site fidelity) and transiency (low site fidelity) to maximize fitness. Uncertainty remains about resident and transient coyote movement patterns and habitat use because research has reached conflicting conclusions regarding patterns of habitat use by both groups. We quantified effects of habitat on resident and transient coyote movement behavior using first passage time (FPT) analysis, which assesses recursive movement along an individual''s movement path to delineate where they exhibit area‐restricted search (ARS) behaviors relative to habitat attributes. We quantified monthly movement rates for 171 coyotes (76 residents and 53 transients) and then used estimated FPT values in generalized linear mixed models to quantify monthly habitat use for resident and transient coyotes. Transients had greater movement rates than residents across all months except January. Resident FPT values were positively correlated with agricultural land cover during fall and winter, but negatively correlated with agriculture during spring. Resident FPT values were also negatively correlated with developed habitats during May–August, deciduous land cover during June–August, and wetlands during September–January except November. FPT values of transient coyotes were positively correlated with developed areas throughout much of the year and near wetlands during July–September. Transient FPT values were negatively correlated with agriculture during all months except June and July. High FPT values (ARS behavior) of residents and transients were generally correlated with greater densities of edge habitat. Although we observed high individual variation in space use, our study found substantive differences in habitat use between residents and transients, providing further evidence that complexity and plasticity of coyote habitat use is influenced by territorial strategy.