scholarly journals Fine-scale biophysical interactions drive prey availability at a migratory stopover site for Phalaropus spp. in the Bay of Fundy, Canada

2013 ◽  
Vol 487 ◽  
pp. 261-273 ◽  
Author(s):  
LH Thorne ◽  
AJ Read
Keyword(s):  
Prey Availability ◽  
Bay Of Fundy ◽  
Fine Scale ◽  
Stopover Site ◽  
Biophysical Interactions ◽  
Migratory Stopover

Variation in diet of Semipalmated Sandpipers (Calidris pusilla) during stopover in the upper Bay of Fundy, Canada

2012 ◽  
Vol 90 (9) ◽  
pp. 1181-1190 ◽  
Author(s):  
J.T. Quinn ◽  
D.J. Hamilton
Keyword(s):  
Diet Composition ◽  
Prey Availability ◽  
Prey Selection ◽  
Bay Of Fundy ◽  
Corophium Volutator ◽  
Stopover Site ◽  
Semipalmated Sandpiper ◽  
Calidris Pusilla ◽  
Isotope Analyses ◽  
Semipalmated Sandpipers

Semipalmated Sandpipers ( Calidris pusilla (L., 1766)) use the upper Bay of Fundy, Canada, as a critical stopover site during their annual fall migration to wintering grounds in South America. While in the area, they feed extensively on mudflat invertebrates. Historically the amphipod Corophium volutator (Pallas, 1766) has been thought to make up the majority of their diet. However, we have recently observed flexibility in foraging behaviour and prey selection by sandpipers. The extent of this flexibility and the current diet composition is unknown. To address these knowledge gaps, we assessed Semipalmated Sandpiper diets using stable isotope analyses of blood plasma and available prey items. Data were collected in two arms of the Bay of Fundy during summer 2009 and 2010. Diets fluctuated between years and sites, but in all cases the diet was much more diverse than previously thought. Polychaetes and biofilm made substantial contributions, and C. volutator was still present in the diet, but at much reduced levels than previously noted. This previously unrecognized inclusion of biofilm in the diet is consistent with recent observations of other calidrid shorebirds. Based on measures of prey availability, there is little evidence of preference for C. volutator.

scholarly journals Fine-scale dietary changes between the breeding and non-breeding diet of a resident seabird

2015 ◽  
Vol 2 (4) ◽  
pp. 140291 ◽  
Author(s):  
Nicole D. Kowalczyk ◽  
André Chiaradia ◽  
Tiana J. Preston ◽  
Richard D. Reina
Keyword(s):  
Prey Availability ◽  
Juvenile Fish ◽  
Fish Communities ◽  
Small Range ◽  
Isotopic Niche ◽  
Fine Scale ◽  
Close Proximity ◽  
Isotope Analyses ◽  
Little Penguin ◽  
Foraging Ranges

Unlike migratory seabirds with wide foraging ranges, resident seabirds forage in a relatively small range year-round and are thus particularly vulnerable to local shifts in prey availability. In order to manage their populations effectively, it is necessary to identify their key prey across and within years. Here, stomach content and stable isotope analyses were used to reconstruct the diet and isotopic niche of the little penguin ( Eudyptula minor ). Across years, the diet of penguins was dominated by anchovy ( Engraulis australis ). Within years, during winter, penguins were consistently enriched in δ 15 N and δ 13 C levels relative to pre-moult penguins. This was probably due to their increased reliance on juvenile anchovies, which dominate prey biomass in winter months. Following winter and during breeding, the δ 13 C values of penguins declined. We suggest this subtle shift was in response to the increased consumption of prey that enter the bay from offshore regions to spawn. Our findings highlight that penguins have access to both juvenile fish communities and spawning migrants across the year, enabling these seabirds to remain in close proximity to their colony. However, annual fluctuations in penguin isotopic niche suggest that the recruitment success and abundance of fish communities fluctuate dramatically between years. As such, the continued monitoring of penguin diet will be central to their ongoing management.

Changes in Growth and Reproduction of Harbour Porpoises, Phocoena phocoena, from the Bay of Fundy

1990 ◽  
Vol 47 (11) ◽  
pp. 2158-2163 ◽  
Author(s):  
Andrew j. Read ◽  
David E. Gaskin
Keyword(s):  
Sexual Maturity ◽  
Prey Availability ◽  
Simultaneous Increase ◽  
Bay Of Fundy ◽  
Commercial Fisheries ◽  
Phocoena Phocoena ◽  
Pronounced Change ◽  
Younger Age ◽  
Incidental Mortality ◽  
Growth And Reproduction

Changes in the growth and reproduction of harbour porpoises from the Bay of Fundy are described by comparing samples collected in 1969–73 and 1985–88. The most pronounced change was an increase in the length of calves, from 92.1 cm (SE 1.6) in 1969–73 to 108 cm (SE 1.3) in 1985–88. Females in 1985–88 attained sexual maturity at a significantly younger age (3.44 yr) and shorter length (143 cm) than females from the older sample (3.97 yr and 147 cm). These changes may be attributable to an increase in prey availability to individual porpoises. This presumed increase in prey availability may have resulted from a decrease in porpoise density caused by incidental mortality in commercial fisheries, a simultaneous increase in prey abundance, or a combination of these factors.

scholarly journals Prey-Driven Behavioral Habitat Use in a Low-Energy Ambush Predator

2020 ◽  
Author(s):  
Annalee M. Tutterow ◽  
Andrew S. Hoffman ◽  
John L. Buffington ◽  
Zachary T. Truelock ◽  
William E. Peterman
Keyword(s):  
Spatial Distribution ◽  
Habitat Selection ◽  
Small Mammal ◽  
Optimal Foraging ◽  
Prey Availability ◽  
Low Energy ◽  
List Type ◽  
Fine Scale ◽  
Timber Rattlesnake ◽  
Ambush Predator

AbstractFood acquisition is an important modulator of animal behavior and habitat selection that can affect fitness. Optimal foraging theory predicts that predators should select habitat patches to maximize their foraging success and net energy gain, which predators can achieve by targeting spaces with high prey availability. However, it is debated whether prey availability drives fine-scale habitat selection for predators.We assessed whether an ambush predator, the timber rattlesnake (Crotalus horridus), exhibits optimal foraging site selection based on the spatial distribution and availability of prey.We evaluated the spatial concordance of radio-telemetered timber rattlesnake foraging locations and passive infrared game camera trap detections of potential small mammal prey (Peromyscus spp., Tamias striatus, and Sciurus spp.) in a mixed-use forest in southeastern Ohio from 2016–2019. We replicated a characteristic timber rattlesnake ambush position by focusing cameras over logs and modeled small mammal encounters across the landscape in relation to remotely-sensed forest and landscape structural features. To determine whether snakes selectively forage in areas with higher prey availability, we projected the estimated prey spatial relationships across the landscape and modeled their overlap of occurrence with observed timber rattlesnake foraging locations.We broadly predicted that prey availability was greatest in mature deciduous forests, but T. striatus and Sciurus spp. exhibited greater spatial heterogeneity compared to Peromyscus spp. We also combined predicted species encounter rates to encompass a body size gradient in potential prey. The spatial distribution of cumulative small mammal encounters (i.e. overall prey availability), rather than the distribution of any one species, was highly predictive of snake foraging.Timber rattlesnakes appear to select foraging locations where the probability of encountering prey is greatest. Our study provides evidence for fine-scale optimal foraging in a low-energy, ambush predator and offers new insights into drivers of snake foraging and habitat selection.

Food web constraints on larval growth in subtropical coral reef and pelagic fishes

2020 ◽  
Vol 650 ◽  
pp. 19-36 ◽  
Author(s):  
MR Gleiber ◽  
S Sponaugle ◽  
KL Robinson ◽  
RK Cowen
Keyword(s):  
Coral Reef ◽  
Prey Availability ◽  
Interactive Effect ◽  
Larval Growth ◽  
Additive Models ◽  
Fish Growth ◽  
Effect Of Temperature ◽  
Fine Scale ◽  
Recent Growth ◽  
Background Density

Prey availability and predation pressure are thought to be key constraints on larval growth, especially in low-productivity, subtropical environments. Yet, measuring their effects on larval fishes has been challenging, given the dynamic biophysical drivers of plankton distributions and small scales of interactions. We integrated fine-scale net tows (10s of meters) with in situ imaging to explore how predator-prey interactions influence larval fish growth in the Straits of Florida. Otolith-derived recent growth was analyzed for 3 ecologically important fishes: 2 coral reef labrids (Thalassoma bifasciatum and Xyrichtys novacula) and 1 tuna (Katsuwonus pelamis), with differing mean growth rates (labrids 0.25 mm d-1, K. pelamis 0.44 mm d-1) and prey (labrids-copepods; tuna-appendicularians). We used generalized additive models to examine the interactive effect of background density and frequency of elevated (>2 SD above background) prey and predators on recent (last 3 d) larval growth. For all taxa, recent growth increased with prey background density. Recent growth of labrids was also higher when copepod densities were more often elevated (14% of transect >20 ind. m-3) above otherwise low background densities (2 ind. m-3). Predators (chaetognaths and hydromedusae) had a growth-selective effect: stronger selection in transects with high-density predator patches, although the direction of the effect was species-specific. The effect of temperature was taxa-specific: growth increased with temperature for the labrids and peaked at an optimum (28°C) for the rapidly growing tuna. Integration of these fine-scale sampling methods improves our understanding of the variable influence of prey and predators on larval growth and, consequently, larval survival.

scholarly journals Assessing Migratory Stopover Site Quality for Birds During Fall Migration Along Two California Rivers

2013 ◽  
Vol 73 (1) ◽  
pp. 72-79 ◽  
Author(s):  
Renée L. Cormier ◽  
Thomas Gardali ◽  
Julian K. Wood
Keyword(s):  
Site Quality ◽  
Stopover Site ◽  
Migratory Stopover

Rusty Blackbirds select areas of greater habitat complexity during stopover

The Condor ◽  
2020 ◽  
Author(s):  
James R Wright ◽  
Luke L Powell ◽  
Stephen N Matthews ◽  
Christopher M Tonra
Keyword(s):  
Habitat Selection ◽  
Shallow Water ◽  
Leaf Litter ◽  
Habitat Complexity ◽  
Radio Telemetry ◽  
Fine Scale ◽  
Patch Selection ◽  
Population Declines ◽  
Stopover Site ◽  
Patch Scale

Abstract The Rusty Blackbird (Euphagus carolinus) is a widespread, uncommon migrant that has experienced heavy population declines over the last century. This species can spend over a quarter of their annual cycle on migration, so it is important to determine their habitat requirements during stopover events to inform effective conservation planning. We assessed their habitat selection at an important stopover site in northern Ohio during both fall and spring migration. Since stopover habitat selection is scale-dependent, we investigated both patch-scale (between patches) and fine-scale (within a patch) selection using radio telemetry to locate foraging and roosting flocks, and compared habitat variables between used and available points across the study site. At the patch scale, we found that birds preferred dogwood–willow swamp, low-lying forest patches, and areas of greater habitat complexity for foraging in both seasons. At the fine scale, spring migrants foraged closer to habitat edges than random, and preferred areas with more wet leaf litter and shallow water, and less grass cover. Fall migrants also preferred shallow water and leaf litter cover, and avoided areas with dense grass, forbs, and herbaceous shrub cover. By contrast, birds consistently roosted in dense stands of emergent Phragmites or Typha marsh, suggesting that the best stopover or staging sites are those with a matrix of different wetland habitats. Although the migratory range of Rusty Blackbirds is currently dominated by agricultural development, our results suggest that fragmented landscapes can still provide adequate habitat for migrants if the available land is managed for a variety of wet habitat types.

Changing with the tides: fine-scale larval fish prey availability and predation pressure near a tidally modulated river plume

2020 ◽  
Vol 650 ◽  
pp. 217-238 ◽  
Author(s):  
K Swieca ◽  
S Sponaugle ◽  
C Briseño-Avena ◽  
MS Schmid ◽  
RD Brodeur ◽  
...  
Keyword(s):  
Imaging System ◽  
Prey Availability ◽  
Fish Larvae ◽  
River Plume ◽  
Fine Scale ◽  
River Plumes ◽  
Temporal Scales ◽  
Spatial Overlap ◽  
Larval Fishes ◽  
Spatio Temporal

Tidally controlled river plumes form distinct frontal boundaries that can alter the spatial distributions of larval fishes and their planktonic prey and predators. Variable in nature, they may expose larval fishes to different trophic environments over small spatio-temporal scales, with unknown consequences for survival and recruitment. In the northern California Current, the Columbia River Plume is strongly influenced by twice-daily freshwater injections that create a highly dynamic coastal environment. Using the In situ Ichthyoplankton Imaging System, we examined changes in the fine-scale horizontal and vertical distributions of larval fishes, their prey, and their predators over space and time (ebb/flood tide). In total, 6095 fish larvae and ~1.5 million prey/predator zooplankton were imaged and measured. Plume regions provided substantially higher concentrations of prey and enhanced spatial overlap between larval fishes and their prey relative to oceanic waters. The functionality of river plumes as a refuge from predators was less clear. Predator concentrations were also higher in plume regions, but overlap with larval fishes was taxon-specific and varied with the tide. Notably, regions of high zooplankton concentrations did not necessarily confer high spatial overlap on small scales (meters vertical, kms horizontal) relevant to trophic interactions. Surface salinity and chlorophyll a were the most important factors influencing the spatial overlap of zooplankton with larval fishes. In the vicinity of river plumes, larval fishes experience a diversity of unique prey and predator fields over short spatio-temporal scales, which likely contribute to variable growth and mortality patterns at much finer scales than previously thought.

Distinct diel and seasonal behaviours in rainbow trout detected by fine-scale acoustic telemetry in a lake environment

2019 ◽  
Vol 76 (8) ◽  
pp. 1432-1445 ◽  
Author(s):  
Breanna M. Watson ◽  
Carlo A. Biagi ◽  
Sara L. Northrup ◽  
Michael L.A. Ohata ◽  
Colin Charles ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Acoustic Telemetry ◽  
Prey Availability ◽  
Time Of Day ◽  
Site Preference ◽  
Activity Levels ◽  
Fine Scale ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Winter Activity ◽  
Diel Movement

The fine-scale behavioural activities of rainbow trout (Oncorhynchus mykiss) in nature are not well understood, but are of importance for identifying interactions with the ecosystem and of interest to conservationists and recreational anglers. We have undertaken a high-resolution acoustic telemetry study to identify the distinct movement patterns of 30 rainbow trout in a freshwater lake, specifically examining swim speed, area of movement, and site preference in both summer and winter. Activity levels were reduced in winter compared with summer across all fish, but ranking of individuals was consistent. In summer, 16/30 fish displayed diel movement, in which they travelled to a different area of the lake at dawn and returned at dusk, while other fish maintained their site preference regardless of the time of day or swam more randomly throughout the lake. These patterns were minimized in winter, where there was a reduction in cross-lake movement under ice and only 4/30 fish displayed diel movement. Winter conditions may limit the capability (physiological limitations) and (or) motivation (prey availability) for diel behaviours observed in summer.

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