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opencc-zeroApr 2020View details →

Seasonal survival and reversible state effects in a long-distance migratory shorebird

1. Events during one stage of the annual cycle can reversibly affect an individual's condition and performance not only within that stage, but also in subsequent stages (i.e., reversible state effects). Despite strong conceptual links, however, few studies have been able to empirically link individual-level reversible state effects with larger-scale demographic processes. 2. We studied both survival and potential reversible state effects in a long-distance migratory shorebird, the Hudsonian Godwit (Limosa haemastica). Specifically, we estimated period-specific survival probabilities across the annual cycle and examined the extent to which an individual's body condition, foraging success, and habitat quality during the nonbreeding season affected its subsequent survival and reproductive performance. 3. Godwit survival rates were high throughout the annual cycle, but lowest during the breeding season, only slightly higher during southbound migration, and highest during the stationary nonbreeding season. Our results indicate that overwintering godwits foraging in high-quality habitats had comparably better nutritional status and pre-migratory body condition, which in turn improved their return rates and the likelihood that their nests and chicks survived during the subsequent breeding season. 4. Reversible state effects thus appeared to link events between nonbreeding and breeding seasons via an individual's condition, in turn affecting their survival and subsequent reproductive performance. Our study thus provides one of the few empirical demonstrations of theoretical predictions that reversible state effects have the potential to influence population dynamics.

opencc-zeroDec 2017View details →

Data from: Habitat-mediated effects of diurnal and seasonal migration strategies on juvenile salmon survival

Behavioral decisions during periods of vulnerability to predation risk, such as migrations during the juvenile life-history stage, may strongly affect the probability of survival. Habitats through which animals migrate are heterogeneous, and risk-reducing behaviors may be more important in some habitats than others. Using biotelemetry data, diurnal and seasonal riverine migration patterns of >3800 juvenile salmon across four species, 12 watersheds, and five years were quantified to evaluate possible effects of migration timing on survival from lower river reaches to coastal waters. In small, clear rivers most salmon avoided migrating during daylight hours, and average survival of fish migrating at night (55%; 95% confidence limits 50–61%) was twice that of fish migrating in daylight (24%; CL 17-31%). Conversely, in the large, heavily silted Fraser River neither preference for nocturnal travel nor effects of diurnal timing on survival were observed. Early ocean survival was also influenced by the timing of ocean entry, but in opposite directions for fish from the Fraser River and smaller rivers. In the Fraser River, average survival for later migrants (69%; CL 60–77%) was nearly twice that of earlier migrants (38%; CL 33–44%), likely related to seasonal increases in river flow. In contrast, in smaller rivers, average survival for earlier migrants (70%; CL 65–74%) was 3-fold greater than survival for later migrants (19%; 95% CL 14–25%). Together these results demonstrate that timing decisions affecting survival of juvenile salmon during their migration are likely mediated by landscape characteristics that plausibly influence the risk of predation.

opencc-zeroDec 2015View details →

Data from: Seed set variation in wild Clarkia populations: teasing apart the effects of seasonal resource depletion, pollen quality, and pollen quantity

In habitats where resource availability declines during the growing season, selection may favor early-flowering individuals. Under such ephemerally favorable conditions, late-blooming species (and individuals) may be particularly vulnerable to resource limitation of seed production. In California, a region prone to seasonal drought, members of the annual genus Clarkia are among the last to flower in the spring. We compared pollen limitation (PL) of seed set and outcrossing rates between early- and late-flowering individuals in two mixed-mating Clarkia taxa to detect whether flowering time is associated with changes in seed set due to resource depletion, PL, or increased selfing. In 2008–2010, we hand-pollinated one flower on a total of 1855 individual plants either Early (near the onset of flowering) or Late (near the end of flowering) in the flowering season and compared seed set to adjacent, open-pollinated flowers on the same stem. To assess the contribution of pollen quality to reproduction, we first (2008) used allozymes to estimate outcrossing rates of seeds produced by Early and Late open-pollinated flowers. Second (2009), we conducted an anther-removal experiment to estimate self-pollen deposition. Seed set in Clarkia unguiculata was not pollen-limited. Clarkia xantiana ssp. xantiana was pollen-limited in 2008 and 2010, but not 2009. PL did not differ between Early and Late treatments. In both taxa, seed set of Early flowers was greater than Late flowers, but not due to PL in the latter. Reproduction was generally pollinator-dependent. Most pollen deposition was xenogamous, and outcrossing rates were >0.7 – and similar between Early and Late periods. These results suggest that pollen receipt and pollen quality remain seasonally consistent. By contrast, the resources necessary to provision seeds decline, reducing the fitness benefits associated with resource allocation to ovules.

opennotspecifiedMar 2003View details →

Fig. 1 in Abundance and Seasonal Distribution of Predatory Coprophilous Argentine Rove Beetles (Coleoptera: Staphylinidae), and Their Effects on Dung Breeding Flies

Fig. 1. Predatory Staphylinidae collected in Castelar, Buenos Aires province: comparative numbers of the most common species per sampling 80 kg of cow dung.

opennotspecifiedMar 2003View details →

Fig. 2 in Abundance and Seasonal Distribution of Predatory Coprophilous Argentine Rove Beetles (Coleoptera: Staphylinidae), and Their Effects on Dung Breeding Flies

Fig. 2. Predatory Staphylinidae collected in El Cadillal, Tucuman province: comparative numbers of the most common species per sampling date in 80 kg of cow dung.

opencc-by-4.0Mar 2024View details →

Disentangling the seasonal effects of agricultural intensification on birds and bats in Mediterranean olive groves

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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-zeroMar 2022View details →

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.

opencc-zeroOct 2022View details →

Effects of El Niño drought on seedling dynamics in a seasonally dry tropical forest in northern Thailand

As El Niño is predicted to become stronger and more frequent in the future, it is crucial to understand how El Niño-induced droughts will affect tropical forests. Although many studies have focused on tropical rainforests, there is a paucity of studies on them, particularly in Asia, and few studies have focused on seedling dynamics, which are expected to be strongly affected by drought. Seedlings in seasonally dry tropical forests (SDTFs) are generally more drought-tolerant than those in the rainforests, and the effects of El Niño-induced droughts may differ between SDTF and tropical rainforests. In this study, we explored the impact of El Niño-induced drought at an SDTF in northern Thailand by monitoring the seedling dynamics at monthly intervals for seven years, including a period of strong El Niño. The effects were compared between two forest types in an SDTF: a deciduous dipterocarp forest (DDF), dominated by deciduous species, and an adjacent lower montane forest (LMF) with more evergreen species. El Niño-induced drought increased seedling mortality in both forest types. The effect of drought was stronger in evergreen than in the deciduous species, resulting in higher mortality in the LMF during El Niño. However, El Niño increased seedling recruitment only in the DDF, mainly because of the massive recruitment of the deciduous oak, Quercus brandisiana (Fagaceae), which compensated for the mortality of seedlings in the DDF. As a result, El Niño increased seedling density in the DDF and decreased it in the LMF. This is the first long-term study to identify the differences in the impacts of El Niño on seedlings between the two forest types, DDF and LMF, and two leaf habits, evergreen and deciduous, in Southeast Asia. Our findings suggest that future climate change may alter the species composition and spatial distribution of seedlings in Asian SDTFs.

opencc-by-4.0Dec 2016View details →

Dataset Disruptive effects of light pollution on sleep in free-living birds: season and/or light intensity-dependent?

Dataset belonging to the article Disruptive effects of light pollution on sleep in free-living birds: season and/or light intensity-dependent?

opencc-by-4.0May 2024View details →

Dataset to paper "The effects of solar radiation on daily and seasonal stem increment of canopy trees in European temperate old-growth forests."

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opencc-by-4.0Jun 2021View details →

Supporting Data for Hahn et al. J. Climate: Seasonality in Arctic Warming Driven By Sea Ice Effective Heat Capacity

This dataset includes CESM model experiment output for Hahn et al.: “Seasonality in Arctic Warming Driven By Sea Ice Effective Heat Capacity” submitted to Journal of Climate. Here we provide monthly climatologies averaged over the last thirty years for the Ice, No ice, and No ice, set albedo experiments with preindustrial and doubled CO2 forcing. The variables hyam, hybm, and P0, useful for interpolating to pressure levels, are included in the FlatSOM1850.Q.nc file.

opencc-zeroMar 2023View details →

Legacy effects of canopy gaps on liana abundance 25 years later in a seasonal tropical evergreen forest in northeastern Thailand

Lianas require host trees to reach and stay in the forest canopy, but as seedlings and juveniles, they benefit from canopy gaps created by treefalls. Here, we evaluated the relative importance of these two aspects, i.e., the availability of potential hosts vs. the legacy effect of past treefall gaps, on the local abundance of liana stems in a seasonal tropical evergreen forest in the Sakaerat Biosphere Reserve in northeastern Thailand. Within a 2.5-ha plot for forest dynamics monitoring, canopy height was measured in 1993 and 2018 at 5-m intervals to distinguish areas of mature (canopy height ≥ 20 m), building (10-20 m), and gap phases (< 10 m). In 2017–2018, we surveyed all liana stems ≥ 1 cm in diameter at breast height within 50 subplots (10 m × 10 m each) and recorded their diameter and the diameter of the host tree. Of a total of 445 liana individuals, 242 could be identified at least to the family level, while the others had clear morphological traits of climbing mechanisms. The number of liana stems was higher in areas that had been at the building/gap phase than those at the mature phase in 1993. When this 25-year-old legacy of past gap locations was considered, there was a positive association of local abundance between lianas and trees in areas at the mature phase in 2018. In conclusion, liana abundance reflected a long-term legacy of past treefall gaps more than 25 years earlier in this seasonal evergreen forest.

FIG. 1 in Effect of Season on Analysis of Growth in a Population of the Western Lesser Siren, Siren intermedia nettingi, in Northwestern Louisiana

FIG. 1. First season capture SVL (mm) frequency (n ¼ 881) for all individuals of Siren intermedia over the seven years of the study (1992– 1998).

FIG. 2 in Effect of Season on Analysis of Growth in a Population of the Western Lesser Siren, Siren intermedia nettingi, in Northwestern Louisiana

FIG. 2. Graph of interaction among years, seasons, and sex on growth in mass of Siren intermedia as calculated by increase in g per day. See Table 3 for statistics.

FIG. 4 in Effect of Season on Analysis of Growth in a Population of the Western Lesser Siren, Siren intermedia nettingi, in Northwestern Louisiana

FIG. 4. Number of Siren intermedia captured per season and year over the five years of the study that sampled all four seasons.

FIG. 3 in Effect of Season on Analysis of Growth in a Population of the Western Lesser Siren, Siren intermedia nettingi, in Northwestern Louisiana

FIG. 3. Graph of interaction among years, seasons, and sex on growth in SVL of Siren intermedia as calculated by increase in mm per day. See Table 4 for statistics.