Foraging Grounds Research Articles

Drivers of avian diversity in urban greenspaces in the Atlantic Forest

Urbanization reduces diversity and alters avian assemblages worldwide. Urban greenspaces can alleviate this effect by promoting habitat for some species, but the relevance of urban greenspaces for megadiverse, Neotropical avifauna is misunderstood. Here, we evaluated whether bird diversity (taxonomic, phylogenetic and functional) and composition would vary with urban greenspace features (size, degree of isolation, heterogeneity and noise) in seven urban greenspaces in southeastern Brazilian coast. Taxonomic diversity was positively related to greenspace size and habitat heterogeneity. Phylogenetic diversity metrics and functional dispersion were not associated with urban greenspace features. Urban greenspaces were dominated by common urban exploiter and non-native species (e.g. Feral Pigeon, Columbia livia, and House Sparrow, Passer domesticus), tanagers (Thraupidae) and tyrants (Tyrannidae), insectivorous and ground foragers, and habitat generalists (only 6 % of forest specialists). Large (and probably more forested) and quiet greenspaces favored forest-dependent species. Species turnover was high among greenspaces (β = 0.64) but was not related to greenspace features. Our results suggest that the number of urban greenspaces, and the larger and/or heterogeneous urban greenspaces, favor higher taxonomically diverse bird communities; and that noise or a noise-related urban feature can erode abundance of forest-dependent species in urban, Neotropical landscapes.

Comparison of benchtop and handheld near‐infrared spectroscopy devices to determine forage nutritive value

AbstractThe quality of predicted plant‐, soil‐, and animal‐response values from near‐infrared (NIR) reflectance spectra depends on the ability to generate appropriate NIR models. The first step in the development of NIR models is collection of spectral data. Limited work, however, has been reported that compares NIR models for prediction of forage nutritive value when the spectra are obtained from devices with different spectral ranges and resolutions. The objectives of this study were to (a) develop and evaluate NIR spectroscopy models using a benchtop‐type (FOSS) and two handheld NIR devices (microPHAZIR and DLP NIRscan Nano EVM) to predict crude protein (CP), acid detergent fiber (ADF), amylase and sodium sulfite‐treated neutral detergent fiber (aNDF), and in vitro true dry matter digestibility (IVTD) of dried ground forage grass samples and (b) compare predictions among the three NIR devices. Switchgrass (Panicum virgatum L.) and bermudagrass [Cynodon dactylon (L.) Pers] hay samples were scanned with the NIR devices and analyzed with wet chemistry for development of NIR prediction models. Among devices, the r2 of validation values for aNDF models ranged from .81 to .87; all other r2 values were >.86 and as high as .98 with standard error of prediction (SEP; g kg−1) ranging from 8.1 to 11.5 for CP, 19.1 to 23.8 for aNDF, 14.2 to 20.0 for ADF, and 26.8 to 49.9 for IVTD. The FOSS benchtop NIR prediction models consistently had the highest r2 and lowest SEP values; however, the predictive power for both handheld devices was similar to the benchtop‐type device.

Frugivores vary in their response to neighborhood effects in a novel ecosystem

Seed dispersal is critical for maintaining ecosystem structure and over half of plant species worldwide rely on animals for dispersal. Animal-mediated seed dispersal requires tight links between animals and plants. The introduction of invasive species threatens this mutualism by potentially creating competition between native and invasive plants for dispersers and by altering the consumption of native fruits by introduced dispersers. Although the first critical step in seed dispersal is fruit consumption, we have limited knowledge of the characteristics that attract dispersers to a given plant. In particular, characteristics of the neighborhood surrounding a plant may alter frugivory and frugivores may vary in their responses to these characteristics. Identification of key neighborhood characteristics would help to identify the mechanisms which facilitate or limit seed dispersal, aiding in the management of species in novel ecosystems. We deployed camera traps on Oʻahu, Hawaiʻi to quantify how the total fruit abundance, percent invasive fruit, percent conspecific fruit, canopy cover, and ground vegetation density of the neighborhood influence visitation and fruit removal by introduced avian frugivores. Results showed that neighborhood effects had little influence on frugivory overall, but did influence avian foraging groups in disparate ways. In particular, visitation by arboreal foragers increased with canopy cover and the amount of fruit on the focal plant but decreased with higher neighborhood fruit abundance and more conspecific fruit. Ground forager visitation decreased with higher ground vegetation density and increased with more conspecific fruit. These findings suggest the neighborhood can be modified to facilitate arboreal foragers, which are higher quality dispersers on Oʻahu, and to limit ground foragers, which are primarily seed predators. We argue studies should consider differences among dispersers to adequately address the role of the neighborhood on frugivory in environments with multiple disperser species.

Bats and bananas: Simplified diet of the nectar-feeding bat Glossophaga soricina (Phyllostomidae: Glossophaginae) foraging in Costa Rican banana plantations

Habitat loss for food production is a problem strongly affecting wildlife. However, some species may adapt their behavior and use these habitats, such as the neotropical nectar-feeding bats (Phyllostomidae: Glossophaginae) occurring in banana monocultures. We assessed the diet of the common nectar-feeding bat Glossophaga soricina, foraging in two habitats with different levels of alteration and land use intensities, conventional and organic banana plantations, and compared it to that from bats living in native forest patches. We collected pollen from the fur of captured bats and identified it under a microscope to the lowest taxonomical level possible. We found that bats foraging in forests have a richer diet, since they feed in more heterogeneous areas with more plant species. Additionally, bats foraging in conventional banana plantations generally showed a less diverse pollen load. One hectare of banana plantation provides an energy density that easily supports five bat individuals per night throughout the year, so plantations might be ideal foraging grounds. However, bats also require proteins, and banana cultivars produce very little or no pollen at all and additionally pesticide use makes insects a scarce resource in most plantations. Such a simplified and incomplete diet and agrochemical exposure might negatively affect the bats, but we still do not understand to what extent. Thus, we conclude that, although banana plantations represent a high nectar availability habitat, they might be less-than-perfect foraging grounds for nectarivorous bats.

Space use and relative habitat selection for immature green turtles within a Caribbean marine protected area

BackgroundA better understanding of sea turtle spatial ecology is critical for the continued conservation of imperiled sea turtles and their habitats. For resource managers to develop the most effective conservation strategies, it is especially important to examine how turtles use and select for habitats within their developmental foraging grounds. Here, we examine the space use and relative habitat selection of immature green turtles (Chelonia mydas) using acoustic telemetry within the marine protected area, Buck Island Reef National Monument (BIRNM), St. Croix, United States Virgin Islands.ResultsSpace use by turtles was concentrated on the southern side of Buck Island, but also extended to the northeast and northwest areas of the island, as indicated by minimum convex polygons (MCPs) and 99%, 95%, and 50% kernel density estimations (KDEs). On average space use for all categories was < 3 km2 with mean KDE area overlap ranging from 41.9 to 67.7%. Cumulative monthly MCPs and their proportions to full MCPs began to stabilize 3 to 6 detection months after release, respectively. Resource selection functions (RSFs) were implemented using a generalized linear mixed effects model with turtle ID as the random effect. After model selection, the accuracy of the top model was 77.3% and showed relative habitat selection values were highest at shallow depths, for areas in close proximity to seagrass, and in reef zones for both day and night, and within lagoon zones at night. The top model was also extended to predict across BIRNM at both day and night.ConclusionMore traditional acoustic telemetry analyses in combination with RSFs provide novel insights into animal space use and relative resource selection. Here, we demonstrated immature green turtles within the BIRNM have small, specific home ranges and core use areas with temporally varying relative selection strengths across habitat types. We conclude the BIRNM marine protected area is providing sufficient protection for immature green turtles, however, habitat protection could be focused in both areas of high space use and in locations where high relative selection values were determined. Ultimately, the methodologies and results presented here may help to design strategies to expand habitat protection for immature green turtles across their greater distribution.

Distribution of whale shark (Rhincodon typus) off northern Peru based on habitat suitability

Abstract In the south‐eastern Pacific Ocean, few studies of whale sharks (Rhincodon typus) exist. In Peru, the northern coast has been identified as the area with the highest presence of whale sharks, yet their ecology in this area is poorly defined. This study predicts the spatial distribution of whale sharks off coastal northern Peru (03°00′S–04°30′S) during La Niña and El Niño seasonal conditions, utilizing maximum entropy modelling. Between 2009 and 2018 (except for 2011), 347 whale sharks were geo‐referenced in northern Peru with greatest data recordings in the austral summer and spring during La Niña events. Depth was the most important predictive variable for spatial distribution of whale sharks, followed by chlorophyll‐a. Sharks were predicted in shallower coastal waters in which chlorophyll‐a values are higher. Habitat suitability was higher in the northern coastal part of the study area. Spring presents the most suitable environmental conditions for whale sharks, both during La Niña and El Niño conditions. The probability of whale shark presence in the north of Peru increases at higher chlorophyll‐a and sea surface temperature values. Therefore, whale sharks appear to aggregate seasonally in northern Peru, potentially exploiting rich foraging grounds. In these areas of high suitability, whale sharks are susceptible to fisheries, bycatch, ship collisions, unmanaged tourism, and pollution; thus, management actions should focus in these areas. This study represents a first step to understand the distribution and habitat suitability of whale shark in Peruvian waters. Further studies should identify suitable habitat for whale sharks in offshore areas. Also, these should focus on the connectivity of these aggregations with other localities in the south‐eastern Pacific in order to contribute to regional strategies for the conservation of this iconic species in this particular region.

Delineating foraging grounds of a loggerhead turtle population through satellite tracking of juveniles

Abstract Tracking of juvenile sea turtles is a research priority to inform the protection of relevant habitats and ensure sustainable rates of recruitment into adult populations. Based on satellite tracking, mixed stock analysis, and mark–recapture studies, Drini Bay in the South Adriatic Sea, Central Mediterranean, has been confirmed as an important foraging site used by loggerhead turtles from all major rookeries in the Mediterranean subpopulation. Three juvenile loggerhead turtles (Caretta caretta) from Drini Bay were tracked for 763, 364, and 211 days respectively. All turtles exhibited different movement patterns. The two smaller turtles ranged widely beyond the bay. One of these (69.5 cm curved‐carapace length; CCL) used the coldest region of the Mediterranean during the first winter of tracking where mean weekly temperatures dipped below 12°C but moved southwards to warmer waters during the second winter. In comparison, the other (66 cm CCL) individual moved south to winter in warmer waters from the outset. Both individuals returned to Drini Bay during summer, demonstrating fidelity to the study site. The third turtle, which was larger (76 cm CCL), remained in Drini Bay for the duration of tracking. These results support the findings of other mark–recapture studies at Drini Bay, which have suggested that the foraging site is being used in a transient way by immature turtles. All three turtles preferentially used the shallow waters (&lt;30 m) in the south of Drini Bay. The study demonstrates a high degree of overlap between the habitat use of the three tracked turtles and that of adult turtles tracked from nesting sites, and although based on a small sample size, contributes to a growing knowledge base regarding the wider habitat use of the Mediterranean loggerhead population.

Genetic Diversity and Demographic Connectivity of Atlantic Green Sea Turtles at Foraging Grounds in Northeastern Colombia, Caribbean Sea

The Atlantic green sea turtle Chelonia mydas is a migratory and endangered species with a network of nesting rookeries and foraging grounds in the Atlantic basin that needs elucidation. Foraging grounds are important areas for immature turtle’s feeding and growth after pelagic migrations. Aggregations of sea turtles at these grounds usually come from genetically distinct nesting rookeries; therefore, they are called mixed stocks. The northeastern coast of Colombia has extensive seagrass and macroalgae marine ecosystems that constitute foraging grounds, and perhaps long-term developmental habitats for a significant number of immature C. mydas. However, it is unknown which C. mydas nesting rookeries may be using these ecosystems for feeding and development. This study estimated the genetic diversity and genetic origin of C. mydas mixed stocks at two foraging grounds in northeastern Colombia (Santa Marta and La Guajira), and inferred their connections to nesting rookeries groups in the Atlantic basin using mitochondrial Control Region (mtCR) as a marker. A high genetic diversity, evidenced by the high nucleotide and haplotype diversities, was found in both studied mixed stocks and may be explained by different contributing nesting rookeries groups found with mixed stock analyses. At least three genetically distinct groups from different sides of the Atlantic Basin contributed juveniles to the mixed stocks in Colombia. Observed demographic connectivity can be explained by the confluence of two major, opposite directions ocean currents by the study area, the Caribbean Current (westward) and the Panama-Colombia Countercurrent (eastward). The high diversity of turtles at Colombia’s foraging grounds suggests the area is an important link in the network of habitats used by C. mydas to be considered in management and transnational conservation planning for the species recovery.

When isotopes fail: importance of satellite telemetry and multi-site validation when estimating the foraging grounds of migratory species

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 633:197-206 (2020) - DOI: https://doi.org/10.3354/meps13179 When isotopes fail: importance of satellite telemetry and multi-site validation when estimating the foraging grounds of migratory species O. I. Coffee1,*, D. T. Booth1, J. A. Thia1, C. J. Limpus2 1The University of Queensland, School of Biological Sciences, St Lucia, Queensland 4072, Australia 2Queensland Government, Department of Environment and Science, Aquatic Threatened Species Unit, Dutton Park, Queensland 4102, Australia *Corresponding author: owen.coffee@uq.net.au ABSTRACT: A combination of δ13C and δ15N isotope ratios, capture-mark-recapture and satellite telemetry data were used to investigate the foraging locations supporting nesting loggerhead turtles Caretta caretta on the Woongarra coastline, southeast Queensland, Australia. Known foraging grounds were available for a subset of these turtles and supplemented with samples taken from foraging turtles to determine whether foraging regions could be identified in untracked nesting turtles using the stable isotopic values of their sampled tissue. Despite the large distances between known foraging regions, no latitudinal gradient was observed in the isotopic values of these turtles. In addition, the isotopic values of foraging individuals from a single site encompassed the range of all loggerhead turtles sampled over the 2000 km north-south distribution along the east coast of Australia. This study demonstrates that assumptions common to δ13C and δ15N stable isotope inference in migratory species are not adhered to globally. Contrasting the successes of stable isotope analysis in the northern hemisphere, these results indicate that factors in the southwest Pacific such as differing prevailing oceanic currents, temperature regimes and river run-offs may prevent the establishment of region-specific unique isoscapes needed for identifying the foraging region of turtles using their isotopic values. Therefore, we caution against the use of δ13C and δ15N stable isotopic values as suitable indicators of foraging regions for loggerhead turtles in Australia. These findings potentially highlight the need to re-evaluate when and where the use of isotopic analysis is appropriate for identifying foraging locations in marine turtle species. KEY WORDS: Loggerhead turtles · Caretta caretta · Carbon isotope · Nitrogen isotope · Migration connectivity Full text in pdf format PreviousNextCite this article as: Coffee OI, Booth DT, Thia JA, Limpus CJ (2020) When isotopes fail: importance of satellite telemetry and multi-site validation when estimating the foraging grounds of migratory species. Mar Ecol Prog Ser 633:197-206. https://doi.org/10.3354/meps13179 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 633. Online publication date: January 09, 2020 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2020 Inter-Research.

Procjena kemijskog sastava voluminozne krme NIR spektroskopijom

Near-infrared spectroscopy (NIR spectroscopy) has been used in analytics for more than 50 years. The aim of this review is to present statistical indicators of the developed calibration models for predicting forage chemical composition by NIR spectroscopy, which have been published over the last 15 years. This paper presents statistics for predicting of forage dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ash, and pH value of forage at different pre-scan processing level (fresh, dried / ground forage) and different forage types such as grass monocultures, legumes, grass-clover mixtures (GCM), semi-natural pasture, straw, maize, hay, silage and haylage. Due to wider applicability of NIR calibration model for prediction of chemical composition of forage, the development of calibration includes forage originating from various agricultural production technologies, cultivation climates, varieties and vegetation seasons, etc. In order to develop more reliable calibration models for prediction of forage chemical composition, calibrations are developed for individual plant species, cultivars, harvest during the vegetation season, as well as for individual microclimates of cultivation. NIR spectroscopy has high potential for predicting the content of DM, CP, NDF, ADF, ash and pH value in forage.

Stable isotope records of sei whale baleens from Chilean Patagonia as archives for feeding and migration behavior.

Carbon (δ13C) and nitrogen (δ15N) stable isotope variations in baleen plates of sei whales (Balaenoptera borealis) stranded after a mass mortality event in Chilean Patagonia were investigated to assess potential dietary and migratory patterns. Carbon and nitrogen isotope ratios of seven baleens from six individuals were analyzed. The δ13C values ranged from − 19.1 to − 15.9‰ and the δ15N values from 8.7 to 15.4‰. Variations of up to 2.9‰ for δ13C and 5.3‰ for δ15N were observed within one baleen. Carbon and nitrogen isotope records of each baleen were significantly correlated and showed recurring oscillations confirmed by wavelet analyses. Oscillations slightly differed in periodicity indicating variable baleen growth rates between 10.0 and 16.5 cm/year. Food sources of the whales are discussed in terms of available isotope data for potential prey taxa and potential migratory behavior on the basis of latitudinal isotope gradients of particulate organic matter. Cyclicity could be explained by regular migrations of the sei whales from subtropical calving areas to high‐latitude foraging grounds. δ15N records of baleens differed between individuals eventually pointing to diverse feeding and migratory preferences among sei whale individuals.

Explaining variation in Colorado songbird blood mercury using migratory behavior, foraging guild, and diet.

Methylmercury is a contaminant of growing global concern that has been shown to accumulate in a variety of taxa, including songbirds. Birds in the same area can accumulate mercury to strikingly different levels. While diet and trophic level clearly play an important role in mercury bioaccumulation and biomagnification, other factors including foraging guilds and migratory behavior may influence mercury levels as well. Here we examine interspecific variation in blood mercury levels in songbirds living in the Fountain Creek watershed on the Front Range of Colorado. We found that the species with the highest mercury had blood mercury concentrations over 75 times higher than the species with the lowest levels. Carnivores had the highest blood mercury levels, but ground foraging and long distance migration also were correlated with higher mercury concentrations. This information may shed light on what species are most at risk from mercury pollution and help to target conservation resources at contaminated sites.

New insights into prime Southern Ocean forage grounds for thriving Western Australian humpback whales

Humpback whale populations migrate extensively between winter breeding grounds and summer feeding grounds, however known links to remote Antarctic feeding grounds remain limited in many cases. New satellite tracks detail humpback whale migration pathways from Western Australia into the Southern Ocean. These highlight a focal feeding area during austral spring and early summer at the southern Kerguelen plateau, in a western boundary current where a sharp northward turn and retroflection of ocean fronts occurs along the eastern plateau edge. The topographic steering of oceanographic features here likely supports a predictable, productive and persistent forage ground. The spatial distribution of whaling catches and Discovery era mark-recaptures confirms the importance of this region to Western Australian humpback whales since at least historical times. Movement modelling discriminates sex-related behaviours, with females moving faster during both transit and resident periods, which may be a consequence of size or indicate differential energetic requirements. Relatively short and directed migratory pathways overall, together with high-quality, reliable forage resources may provide a partial explanation for the ongoing strong recovery demonstrated by this population. The combination of new oceanographic information and movement data provides enhanced understanding of important biological processes, which are relevant within the context of the current spatial management and conservation efforts in the Southern Ocean.

Contrasting Habitat Use and Population Dynamics of Reef Manta Rays Within the Nusa Penida Marine Protected Area, Indonesia

Manta rays (Mobula spp.) are highly valued in nature-based tourism globally. In Indonesia, although manta rays are protected, critical information is lacking on their habitat use, population dynamics and movements. We investigate the population structure and residency patterns of reef manta rays (Mobula alfredi) in the Nusa Penida Marine Protected Area (MPA). From photo-identification data logged by citizen scientists and trained observers (mantamatcher.org), we identified 624 reef manta rays from 5,913 sightings (January 2012–April 2018) based on their unique ventral coloration patterns. Year-round records were collected from two shallow (<20 m) reefs – Manta Bay (MB; n = 3,029 sightings) and Manta Point (MP; n = 3,058) – that are used frequently by tourism operators. Maximum likelihood techniques and a Markov movement analysis were used to model residency patterns and movement between these sites within the MPA. Manta rays at MB were predominantly male (64%, n = 261 individuals), with immature males (14%, n = 59) being sighted most frequently (39%, n = 1,170). In contrast, few immature individuals were sighted at MP (6%, n = 28), and they were sighted on few occasions (2%, n = 45), while mature female manta rays comprised 26% (n = 127) of the MP community and were the most frequently sighted (48%, n = 1,413). Lagged identification rates indicated high site fidelity at each location. However, 44% (n = 278) of individuals moved between the two sites and cumulative discovery curves showed a continued recruitment of individuals over the 6 years of the study. In addition, the behaviors displayed by the manta rays differed markedly between the two sites: MB appears to be a foraging ground, especially for juveniles, and potentially a nursery, while MP is used mainly for cleaning and courtship, indicating a social and reproductive site. Reproductive behavior coincided with the peak annual sightings in May. To prevent disturbance to this threatened species by tourism, regulations for the number of boats and interactions, especially during key reproductive times should be considered. Further, strict fishing regulation in the area is recommended as fishing gear entanglement was identified as a threat to this population.

Genetic analysis and satellite tracking reveal origin of the green turtles in San Diego Bay

Understanding population structure and migration patterns is critical for conservation of marine species that undertake seasonal migrations, often spanning entire oceans, between breeding grounds and distant feeding areas. To examine the stock origin of the green turtle foraging aggregation in San Diego Bay, California, USA (32.6°N, 117.1°W) and evaluate current life history hypotheses, 770 bp sequences of the mitochondrial DNA control region from 121 green turtles captured in San Diego Bay were compared to potential source (nesting) populations across the Pacific. Mixed stock analysis indicated that the San Diego Bay foraging population originates from eastern Pacific nesting sites, primarily the Revillagigedo Archipelago and the coast of Michoacan, Mexico. To further understand migratory pathways and breeding destinations, three mature female turtles were satellite tracked from the San Diego Bay foraging ground (FG), including one turtle tracked for 364 days that nested at Socorro Island in Revillagigedo and returned to San Diego Bay (total distance approx. 3200 km), one of the first continuous satellite tracks of a sea turtle from a FG to its nesting site and back. Tracks from another turtle indicated possible nesting at Tres Marias Islands, approximately 100 km off the Mexican mainland coast. All three turtles have subsequently been recaptured in San Diego Bay, indicating a high degree of FG philopatry. These results rule out previous speculation that Hawaiian green turtles were also using San Diego Bay, provide insights into the distribution of the Revillagigedo Islands and Michoacan breeding populations and draw attention to the Tres Marias Islands as a potential source of green turtles in the temperate North Pacific.

Inter-rater Reliability of Participatory Evaluation Data - &lt;i&gt;Brachiaria&lt;/i&gt; Grasses in Nyandarua

This study investigates the place of various physical attributes of 8 different Brachiaria grasses and two common grass species used by farmer — Napier and Rhodes grass. A list of 5 attributes including the ability of the grass to cover the ground, hairiness, harvesting height, pest and disease resistance and forage amount were used to evaluate these grasses in order to choose the best performers. Using this list of attributes, farmers were asked to evaluate these grasses replicated in 4 plots at the KALRO DRI Sub Centre; Ol Joro Orok. The data generated from the evaluation was subjected to a consistency check by use of the intraclass correlation coefficient. Results imply that for some less visible traits such as resistance to biotic stresses (pests and diseases), the evaluators can fail the consistency test. On the other hand, ratings for traits such as plant cover and height, which are easily observable were consistent. The discussion points to the need for careful use of methods and the need to perform reliability checks when using such participatory evaluation approaches. Whereas the paper does not provide a clinical prognosis, it provides a reminder to procedures which we think are rarely reported of are largely ignored in such participatory evaluations.

Grazing improves habitat suitability for many ground foraging birds in Mediterranean wooded grasslands

Wooded grasslands, usually grazed, cover vast areas in Southern Europe and Northern Africa. They host rich resident bird communities and, in winter, receive large numbers of migrants from Central and Northern European woodlands. Many species are partly or entirely dependent on ground foraging and, since in winter food is often the most limiting factor for birds, maintaining suitable ground habitat is crucial.To study how grazing influences suitability of winter ground habitat for birds, we carried out an experiment in a wooded grassland in Southern Iberia, whereby grazing was controlled in 12 purposely fenced two-hectare plots (4 × 15 sheep/ha, 4 × 3 sheep/ha and 4 × no grazing). We quantified ground habitat features, food abundance and intensity of use by ground-foraging birds in each of these 12 plots. In addition, we made focal observations of birds feeding on the ground and compared the habitat of 1m2 foraging patches with those of nearby control patches.We found that virtually all birds prefer to forage in patches with short ground vegetation and high food abundance. Measurements of these parameters in the experimental plots showed that while grazing shortens vegetation it decreases food availability, and thus has opposing effects on important determinants of habitat suitability. Nevertheless, the numbers of birds foraging in the plots indicate that, overall, grazing benefits the assemblage of ground-feeding birds, presumably because for most species the advantages of foraging in less cluttered habitats more than compensate the lower abundance of prey. However, arboreal bird species that make short foraging forays to the ground had lower numbers in grazed plots.Most bird species that forage on the ground benefited from grazing, and although they can forage under a broad range of grazing levels, some showed clear preferences along the gradient of grazing intensity. Such preferences should be taken into consideration by managers. In general, grazing should be maintained at a level sufficient to open up ground vegetation, increasing the area occupied by patches of short vegetation, in which almost all bird species prefer to forage. At moderate levels, grazing is thus a valuable management tool to promote winter bird habitat quality in Mediterranean wooded grasslands, while increasing the economic value of these threatened landscapes.

Navigating snowscapes: scale-dependent responses of mountain sheep to snowpack properties.

Winters are limiting for many terrestrial animals due to energy deficits brought on by resource scarcity and the increased metabolic costs of thermoregulation and traveling through snow. A better understanding of how animals respond to snow conditions is needed to predict the impacts of climate change on wildlife. We compared the performance of remotely sensed and modeled snow products as predictors of winter movements at multiple spatial and temporal scales using a data set of 20,544 locations from 30 GPS-collared Dall sheep (Ovis dalli dalli) in Lake Clark National Park and Preserve, Alaska, USA from 2005 to 2008. We used daily 500-m MODIS normalized difference snow index (NDSI), and multi-resolution snow depth and density outputs from a snowpack evolution model (SnowModel), as covariates in step selection functions. We predicted that modeled snow depth would perform best across all scales of selection due to more informative spatiotemporal variation and relevance to animal movement. Our results indicated that adding any of the evaluated snow metrics substantially improved model performance and helped characterize winter Dall sheep movements. As expected, SnowModel-simulated snow depth outperformed NDSI at fine-to-moderate scales of selection (step scales < 112 h). At the finest scale, Dall sheep selected for snow depths below mean chest height (<54 cm) when in low-density snows (100kg/m3 ), which may have facilitated access to ground forage and reduced energy expenditure while traveling. However, sheep selected for higher snow densities (>300kg/m3 ) at snow depths above chest height, which likely further reduced energy expenditure by limiting hoof penetration in deeper snows. At moderate-to-coarse scales (112-896 h step scales), however, NDSI was the best-performing snow covariate. Thus, the use of publicly available, remotely sensed, snow cover products can substantially improve models of animal movement, particularly in cases where movement distances exceed the MODIS 500-m grid threshold. However, remote sensing products may require substantial data thinning due to cloud cover, potentially limiting its power in cases where complex models are necessary. Snowpack evolution models such as SnowModel offer users increased flexibility at the expense of added complexity, but can provide critical insights into fine-scale responses to rapidly changing snow properties.

Source levels of foraging humpback whale calls.

Humpback whales produce a wide range of low- to mid-frequency vocalizations throughout their migratory range. Non-song "calls" dominate this species' vocal repertoire while on high-latitude foraging grounds. The source levels of 426 humpback whale calls in four vocal classes were estimated using a four-element planar array deployed in Glacier Bay National Park and Preserve, Southeast Alaska. There was no significant difference in source levels between humpback whale vocal classes. The mean call source level was 137 dBRMS re 1 μPa @ 1 m in the bandwidth of the call (range 113-157 dBRMS re 1 μPa @ 1 m), where bandwidth is defined as the frequency range from the lowest to the highest frequency component of the call. These values represent a robust estimate of humpback whale source levels on foraging grounds and should append earlier estimates.

Sporadic nesting reveals long distance colonisation in the philopatric loggerhead sea turtle (Caretta caretta)

The colonisation of new suitable habitats is crucial for species survival at evolutionary scale under changing environmental conditions. However, colonisation potential may be limited by philopatry that facilitates exploiting successful habitats across generations. We examine the mechanisms of long distance dispersal of the philopatric loggerhead sea turtle (Caretta caretta) by analysing 40 sporadic nesting events in the western Mediterranean. The analysis of a fragment of the mitochondrial DNA and 7 microsatellites of 121 samples from 18 of these nesting events revealed that these nests were colonising events associated with juveniles from distant populations feeding in nearby foraging grounds. Considering the temperature-dependent sex determination of the species, we simulated the effect of the incubation temperature and propagule pressure on a potential colonisation scenario. Our results indicated that colonisation will succeed if warm temperature conditions, already existing in some of the beaches in the area, extend to the whole western Mediterranean. We hypothesize that the sporadic nesting events in developmental foraging grounds may be a mechanism to overcome philopatry limitations thus increasing the dispersal capabilities of the species and the adaptability to changing environments. Sporadic nesting in the western Mediterranean can be viewed as potential new populations in a scenario of rising temperatures.