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opencc-zeroDec 2021View details →

Seasonal strategies differ between tropical and extratropical herbivores

Seasonal diet shifts and migration are key components of large herbivore population dynamics, but we lack a systematic understanding of how these behaviors are distributed on a macroecological scale. The prevalence of seasonal strategies is likely related to herbivore body size and feeding guild, and may also be influenced by properties of the environment, such as soil nutrient availability and climate seasonality. We evaluated the distribution of seasonal dietary shifts and migration across large-bodied mammalian herbivores and determined how these behaviors related to diet, body size, and environment. We found that herbivore strategies were consistently correlated with their traits: seasonal diet shifts were most prevalent among mixed feeding herbivores and migration among grazers and larger herbivores. Seasonality also played a role, particularly for migration, which was more common at higher latitudes. Both dietary shifts and migration were more widespread among extratropical herbivores, which also exhibited more intermediate diets and body sizes. Our findings suggest that strong seasonality in extratropical systems imposes pressure on herbivores, necessitating widespread behavioral responses to navigate seasonal resource bottlenecks. It follows that tropical and extratropical herbivores may have divergent responses to global change, with intensifying herbivore pressure in extratropical systems contrasting with diminishing herbivore pressure in tropical systems.

opencc-by-4.0Jan 2022View details →

Human recreation impacts seasonal activity and occupancy of American black bears (Ursus americanus) across the urban-wildlife interface

The datasets used for all analyses throughout the study that are downloaded from the Yooper Wildlife Watch Project found on Zooniverse.

opencc-zeroJan 2022View details →

Dry season intensity has equivocal effects on the nutritional condition of understory birds in a Neotropical forest

Rainfall regime, the amount and timing of annual precipitation, can influence the breeding phenology, individual fitness, and population dynamics of tropical birds. In Neotropical regions with rainfall seasonality (i.e., wet and dry seasons), the warm phase of the El Niño Southern Oscillation (ENSO) can exacerbate seasonal drought and negatively impact avian survival and reproduction. However, the mechanisms underlying associations between seasonal drought conditions and avian demography are largely unexplored. One hypothesis is that nutritional condition mediates demographic responses to seasonal drought– individuals in poor condition may be less capable of balancing their energy budgets and consequently suffer reduced survival, lower reproductive output, or both. We estimated nutritional condition (i.e., scaled mass index, percent hematocrit, plasma lipid metabolites) as a proxy of energy balance in understory forest birds with contrasting population-level responses to dry season length. This study took place across two dry seasons of differing intensity in central Panama– an El Niño dry season (2016, severe drought) and a more typical dry season (2017). Scaled mass index remained relatively constant throughout both dry seasons and across years for five common focal species and among four foraging guilds (22 additional species, 27 species total). Three of five focal species did exhibit reduced nutritional condition (i.e., lower hematocrit and/or higher β-hydroxybutyrate) during the El Niño dry season but not during the more typical dry season. However, foraging guilds did not show consistent nutritional responses to seasonal drought and we found little evidence of reduced nutritional condition at the guild level, suggesting that many Neotropical forest bird species are capable of tolerating seasonal drought.

opencc-zeroJan 2022View details →

Influence of habitat quality and resource density on breeding-season female monarch butterfly (Danaus plexippus) movement and space use in north-central USA agroecosystem landscapes

<ol> <li> The eastern North American monarch butterfly is at risk of quasi-extinction due, in part, to the loss of breeding habitat in agricultural landscapes of the USA Midwest. Because adult females are not patch residents, egg abundance and distribution across the landscape are a function of their perceptual range, flight directionality, and flight step lengths. Conservation actions that account for habitat use in agricultural landscapes can enhance functional connectivity.</li> <li>Field-captured females (n=114) were released in a 64-ha area containing restored prairies, grass-dominated fields, and crop fields in Floyd County, Iowa, USA, and two 1,000 m linear north-south sections of grass-dominated roadside along secondary roads (~ 35 ha) with different proximity to prairie habitat in rural Story County, Iowa. Radio-tagged or untagged monarchs were released in areas with high-density, low-density, and zero density of forage and oviposition resources, as well as on habitat edges between high and zero-density habitats. Monarchs were observed for one hour. Radio-tagged individuals that flew beyond visual detection were relocated using handheld radio telemetry.</li> <li>Monarchs moved within and between habitat classes and typically performed up-wind search behavior. Monarchs successfully located resources, with some flying over 500 m to find high-density areas, providing evidence that the monarch's perceptual distance is > 100 m. Regardless of habitat class or field site, most step lengths were < 50 m, and turn angles were directional. Large steps (≥ 50 m) crossing habitat boundaries occurred with approximately half of the monarchs, which may indicate initiation of long-range searches for suitable habitat, consistent with their vagile behavior. Establishing habitat patches 50 m apart in agricultural landscapes would facilitate efficient movement.</li> <li>This study provides an extensive dataset of directly observed breeding-season monarch butterflies to assess the utilization of agricultural landscapes. Documentation of step lengths > 50 m in complex, agricultural landscapes would not have been possible without the aid of radio telemetry. Results provide improved estimates of perceptual range and flight patterns within and between habitat patches that support models that simulate natural population dynamics to enable conservation planning at a landscape scale.</li> </ol>

opencc-by-4.0Jan 2022View details →

Code and data for "Seasonal Surface Eddy Mixing in the Kuroshio Extension: Estimation and Machine Learning Prediction" By Guan et al. Submitted to JGR Oceans.

This repository contains the code and data for the machine learning analysis of "Seasonal Surface Eddy Mixing in the Kuroshio Extension: Estimation and Machine Learning Prediction”By Guan et al. Submitted to JGR Oceans. Specifically, this repository contains the following items: (1) Codes for assessing the representation skill of the machine learning and linear regression (LR) methods. Three machine learning methods are considered: random forest (RF), back-propagation neural network (BP), and convolutional neural network (CNN). (2) Codes for assessing the prediction skill of the machine learning and LR methods.   (3) Seasonal-mean and annual-mean input data to run these codes.   (4) The package needed to run the random forest code, i.e. the RF_MexStandalone-v0.02 program package from https://code.google.com/archive/p/randomforest-matlab/downloads .

opencc-by-4.0Jan 2022View details →

Opportunities for seasonal forecasting to support water management outside the tropics: Supplementary information

Supporting information for Jackson-Blake et al. (2022), 'Opportunities for seasonal forecasting to support water management outside the tropics', HESS Contents (section numbers refer to sections in the HESS paper): <ul> <li>SI1_CatchmentMaps.pdf: Catchment maps for each of the five case study sites.</li> <li>SI2_FirstSurvey_HistoricEvent.pdf: Questions asked as part of the first assessment exercise described in Section 3. In this exercise, stakeholders were asked to pick a historic season when there were problems in their catchment/lake, and then seasonal forecasts were produced for that season. Stakeholders were then asked a set of questions designed to assess: (1) their interpretation of the forecasts, and (2) to what extent they thought forecasts would have been useful for them. Full questions and answers are provided in this pdf.</li> <li>SI3_WindowsOfOpportunity_Responses.xlsx: Full responses to the questionnaire described in Sections 2.2 and 3.2.</li> </ul>

opencc-by-4.0Feb 2022View details →

Tracks for "Attribution of 2020 hurricane season extreme rainfall to human-induced climate change"

TempestExtremes track files for CAM5 analysis presented in "Attribution of 2020 hurricane season extreme rainfall to human-induced climate change"

FIGURE 3 in Influence of seasonality on wing morphological variability in populations of Mansonia amazonensis (Theobald) (Diptera: Culicidae)

FIGURE 3. Diagrams of conformation variation between landmarks for Principal Component 1 (PC1) and 2 (PC2). Light blue lines represent consensus conformations and dark blue lines correspond to the conformation trends.

FIGURE 2 in Influence of seasonality on wing morphological variability in populations of Mansonia amazonensis (Theobald) (Diptera: Culicidae)

FIGURE 2. Dorsal view of the right wing of a female of Mansonia amazonensis captured in the area of the Amazon Hydroelectric Development Unit of Jirau (UHE-Jirau), Rondônia State, Brazil. The numbers represent the position of the landmarks. Scale = 1 mm.

FIGURE 1 in Influence of seasonality on wing morphological variability in populations of Mansonia amazonensis (Theobald) (Diptera: Culicidae)

FIGURE 1. Sampling point for populations of Mansonia amazonensis in the area of the Amazon Hydroelectric Development Unit of Jirau (UHE-Jirau), Rondônia State, Brazil, during the dry, rainy and transition periods of 2018 and 2019.

FIGURE 4 in Influence of seasonality on wing morphological variability in populations of Mansonia amazonensis (Theobald) (Diptera: Culicidae)

FIGURE 4. Canonical analysis of shape variables of 181 specimens of Mansonia amazonensis according to dry, rainy and transition periods of 2018 and 2019 in the area of the Amazon Hydroelectric Development Unit of Jirau (UHE-Jirau), Rondônia State, Brazil. Each point indicates an individual, and the ellipses indicate the confidence interval (90%). Numbers identify groups of specimens collected during different periods: (2) July/18, dry season; (3) October/18, rainy season; (4) December/18, rainy season; (5) April/19, rainy season; (6) July/19, dry season; (7) September/19, transition period; (8) December/19, rainy season.

opencc-zeroFeb 2022View details →

Patterns of Testosterone in Male White-tailed Deer (Odocoileus virginianus): Seasonal and Lifetime Variation

Testosterone is strongly associated with the annual development of antlers in cervids, but. endocrine research on wild, freely breeding ungulates is often done without repeated capture of known-aged individuals. As a result, our knowledge on how testosterone fluctuates over the course of a lifetime and variation in lifetime patterns among individuals is limited. We investigated patterns of testosterone in a freely breeding population of white-tailed deer (Odocoileus virginianus) in Alabama, USA that breeds in January. Testosterone peaked during the height of the breeding season, despite this period occurring approximately two months later than in most temperate-region, white-tailed deer populations. Age-related differences in testosterone were only prevalent during the breeding season, with bucks ≥3.5 years old having greater testosterone (853 ng/dl ±96 SE; P = 0.012) than bucks 1.5–2.5 years old (364 ng/dl ±100 SE). Additionally, an individual's testosterone level as a yearling was not positively associated with their lifetime maximum testosterone level (P = 0.583), and an individual's mean testosterone level was positively associated with lifetime testosterone variation (P < 0.001). To our knowledge our study is one of the first to assess how testosterone early in life might relate to individual testosterone later in life. We believe these data provide insight into lifetime hormonal patterns in cervids, and that these patterns may indicate intraspecific variation of lifetime reproductive strategies.

opencc-by-4.0Feb 2022View details →

Derived products from "Beyond glacier wide mass balances: parsing seasonal elevation change into spatially-resolved patterns of accumulation and ablation at Wolverine Glacier, Alaska"

Distributed mass balances, emergence velocities, firn compaction rates, and co-registered 10 m resolution DEMs from "Beyond glacier wide mass balances: parsing seasonal elevation change into spatially-resolved patterns of accumulation and ablation at Wolverine Glacier, Alaska" (in review) (Zeller et al., 2022).

Coping with seasonality: dynamics of adult body mass and survival in an alpine hibernator

Alpine mammals are highly vulnerable to current and projected climate change because they are confined to a certain elevation range. Physiological and behavioural adaptations in burrowing species, such as finding shelter in burrows when the summer conditions are unfavorable and hibernating in winter during the stressful period of resource shortage, could partly buffer the negative impacts of these forecasted changes. We studied the links between environmental factors and annual variations in adult mass and survival over 14 years in hoary marmots. We hypothesized that annual variation in seasonal environmental factors determines individual mass and survival through direct effects on food quality and availability, expecting greater survival when marmots reach higher mass before hibernation. We found that harsh winters decreased mass at emergence from hibernation by 47% compared with mild winters. Nonetheless, adult marmots had a greater mass gain in summers following harsh winters and reached a similar mass at the end of the summer compared with summers following mild winters. This result suggests individuals can adopt a resource allocation strategy that allows maximizing summer mass gain to survive hibernation. Earlier springs also increased summer mass gain by 15 g/day, and tended to increase apparent adult survival by 23%, compared with late springs. While these findings suggest a warming climate could have positive effects on summer mass gain and survival, survival also tended to decrease by 24% in summers with more precipitation. This result suggests the forecasted changes in precipitation extremes could also trigger considerable negative effects on the demography of burrowing species in the long term. Our study shows that, although burrowing and hibernating behaviours could buffer responses to environmental changes, these behaviours are not an indefectible shield against climate change.

Responses to natural gas development differ by season for two migratory ungulates

While migrating, animals make directionally persistent movements and may only respond to human-induced rapid environmental change (HIREC), such as climate and land-use change, once a threshold of HIREC is surpassed. In contrast, animals on other seasonal ranges (e.g., winter range) make more localized and tortuous movements while foraging and may have the flexibility to adjust the location of their range and the intensity of use within it to minimize interactions with HIREC. Because of these seasonal differences in movement, animals on seasonal ranges should avoid areas that contain any level of HIREC, however, during migration, animals should use areas that contain low levels of HIREC, avoiding it only once a threshold of HIREC has been surpassed. We tested this hypothesis using a decade of GPS collar data collected from migratory mule deer (Odocoileus hemionus; n = 56 migration, 143 winter) and pronghorn (Antilocapra americana; n = 70 migration, 89 winter) that winter on and migrate through a natural gas field in western Wyoming. Using surface disturbance caused by well pads and roads as an index of HIREC, we evaluated behavioral responses across three spatial scales during winter and migration seasons. During migration, both species tolerated low levels of disturbance. Once a disturbance threshold was surpassed, however, they avoided HIREC. For mule deer, thresholds were consistently ~3%, whereas thresholds for pronghorn ranged from 1-9.25% surface disturbance. In contrast to migration, both species generally avoided all levels of HIREC while on winter range. Our study suggests that animal responses to HIREC are mediated by season-specific movement patterns. Our results provide further evidence of ungulates avoiding human disturbance on winter range and reveal disturbance thresholds that trigger mule deer and pronghorn responses during migration – information that managers can use to maintain the ecological function of migration routes and winter ranges.

Pastures and climate extremes: Impacts of cool season warming and drought on the productivity of key pasture species in a field experiment

Shifts in the timing, intensity and/or frequency of climate extremes, such as severe drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in Southeast Australia was designed to investigate the impacts of a severe winter/spring drought (60% rainfall reduction) and, for a subset of species, a factorial combination of drought and elevated temperature (ambient +3 °C) on pasture productivity. The experiment included nine common pasture and Australian rangeland species from three plant functional groups (C3 grasses, C4 grasses and legumes) planted in monoculture. Winter/spring drought resulted in productivity declines of 45% on average and up to 74% for the most affected species (Digitaria eriantha) during the 6-month treatment period, with eight of the nine species exhibiting significant yield reductions. Despite considerable variation in species' sensitivity to drought, C4 grasses were more strongly affected by this treatment than C3 grasses or legumes. Warming also had negative effects on cool-season productivity, associated at least partially with exceedance of optimum growth temperatures in spring and indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in the greatest yield reductions. We identified responses that were either additive such that there was only as significant warming effect under drought (Festuca), or less-than-additive, where there was no drought effect under warming (Medicago), compared to ambient plots. Results from this study highlight the sensitivity of diverse pasture species to increases in winter and spring drought severity similar to those predicted for this region, and that anticipated benefits of cool-season warming are unlikely to be realised. Overall, the substantial negative impacts on productivity suggest that future, warmer, drier climates will result in shortfalls in cool-season forage availability, with profound implications for the livestock industry and natural grazer communities.

A tail of plumage colouration: disentangling geographic, seasonal, and dietary effects on plumage colour in a migratory songbird

Plumage ornamentation in birds serves critical inter- and intra-sexual signaling functions. While carotenoid-based plumage colouration is often viewed as a classic condition dependent sexually selected trait, plumage colouration can be influenced by a wide array of both intrinsic and extrinsic factors. Understanding the mechanisms underlying variation in colouration is especially important for species where the signaling function of ornamental traits is complex or the literature conflicting. Here, we examined variation in the yellow/orange tail feathers of American redstarts (Setophaga ruticilla) passing through two migratory stopover sites in eastern North America during both spring and fall migration to assess the role of geographic variation and seasonality in influencing feather colouration. In addition, we investigated whether diet during moult (inferred via stable isotope analysis of feather δ15N and δ13C) influenced plumage colouration. Our findings indicate that geographic variation, season, and diet all influence individual differences in American redstart colouration, represented by both traditional and tetrahedral colour variables. The extent to which these factors influence colour expression however is largely dependent on the colour metric under study, likely because different colour metrics reflect different attributes of the feather (e.g., structural components vs. pigment deposition). The effects of diet (δ15N) and season were pronounced for brightness, suggesting a strong effect of diet and feather wear/degradation on feather structure. Though hue, a metric that should strongly reflect pigment deposition, also changed from spring to fall, that effect was dependent on age, with only adults experiencing a reduction in ornamentation. Taken together, our results highlight the numerous sources of variation behind plumage coloration and underscores the difficulty of unraveling complex visual signaling systems, such as those in American redstarts.

Low-coverage whole-genome sequencing reveals molecular markers for spawning season and sex identification in Gulf of Maine Atlantic cod (Gadus morhua, Linnaeus 1758)

Atlantic cod (Gadus morhua, Linnaeus 1758) in the western Gulf of Maine are managed as a single stock despite several lines of evidence supporting two spawning groups (spring and winter) that overlap spatially, while exhibiting seasonal spawning isolation. Low-coverage whole genome sequencing was used to evaluate the genomic population structure of Atlantic cod spawning groups in the western Gulf of Maine and Georges Bank using 222 individuals collected over multiple years. Results indicated low total genomic differentiation, while also showing strong differentiation between spring and winter spawning groups at specific regions of the genome. Guided regularized random forest and ranked FST methods were used to select panels of single nucleotide polymorphisms (SNPs) that could reliably distinguish spring and winter-spawning Atlantic cod (88.5% assignment rate), as well as males and females (95.0% assignment rate) collected in the western Gulf of Maine. These SNP panels represent a valuable tool for fisheries research and management of Atlantic cod in the western Gulf of Maine that will aid investigations of stock production and support accuracy of future assessments.

Data from: Seasonal and functional variation in the trophic base of intermittent Alpine streams

In high-altitude Alpine streams, seasonal cycles of snowmelt, glacial melt, and rainfall drive variation in the availability of algal food resources. Yet high-altitude streams also exhibit varying degrees of flow intermittency, from solely winter-drying streams to others that dry periodically throughout summer and autumn. These environmental drivers may interact in different ways to determine the functional trophic base of macroinvertebrates inhabiting high-altitude streams. Here, we estimated the proportional contribution of autochthonous resources to the assimilated diets of benthic macroinvertebrates in 26 headwater streams of Val Roseg, a high Alpine glacial catchment, using stable isotope analysis (δ13C and δ15N) of different macroinvertebrate families and their potential food sources. We compared dietary estimates along a gradient of flow intermittency and across 3 seasons (Alpine spring, summer and autumn). Assimilation from autochthonous sources was highest for collector-gatherers and filter feeders in spring, and for grazers in summer. Grazers had higher estimated assimilation from autochthonous sources in intermittent streams than in perennial streams, particularly in summer, while collector-gatherers showed little effect of flow intermittency on dietary estimates. However, responses were highly taxon-specific, with different responses to variation in flow intermittency and season across families within functional groups. Our results suggest that frequent summer drying events represent trade-offs between greater access to algal food resources and a higher risk of desiccation, but that differing life-history and functional feeding traits across macroinvertebrate taxa drive marked variation in the risks or benefits associated with inhabitants of drying streams.

Data from: Prairie dogs, cattle subsidies, and alternative prey: Seasonal and spatial variation in coyote diet in a temperate grassland

As the dominant predator on North America's grasslands, coyotes (Canis latrans) have a large influence on biodiversity, both on working ranches and in protected parks. Ground squirrel (sciurid) species and livestock carrion are often abundant on grasslands worldwide and have the potential to influence a predator's consumption of alternative prey. We collected 1321 scats in four seasons over two years in and adjacent to Grasslands National Park, Saskatchewan, to test the hypothesis that seasonal and spatial variation in consumption of sciurid prey and cattle (Bos taurus) carrion influenced coyote consumption of alternative prey. Sciurid (black-tailed prairie dog Cynomys ludovicianus and Richardson's ground squirrel Urocitellus richardsonii) remains were common from spring to fall and had a strong inverse relationship with deer (mule deer Odocoileus hemionus and white-tailed deer O. virginianus), which were most common in winter scats. Cattle remains were most common during spring, fall and winter, occurring in 10.6% of scats annually. Biomass estimates indicated that cattle was the highest ranked food on cattle grazing land year-round, and the 2nd ranked food, after deer, during winter on the portion of the park from which cattle were excluded. Closer proximity of scats to a prairie dog colony increased the likelihood of prairie dog remains throughout the year and reduced the likelihood of cattle remains in scats from spring to fall, but not during winter. Individual differences in foraging and ranging behavior may explain the spatial distribution of prairie dog versus cattle in scats. Further work is needed to determine whether sciurid prey, deer, or livestock carrion support large predator populations on grassland habitats to a level that may negatively affect coexisting prey species, including species at risk.