Feeding ecology and behavior of postbreeding male Blue-winged Teal and Northern Shovelers

1985 ◽  
Vol 63 (6) ◽  
pp. 1292-1297 ◽  
Author(s):  
Paul J. DuBowy
Keyword(s):  
Foraging Strategies ◽  
Feeding Behaviors ◽  
Foraging Mode ◽  
Time Activity ◽  
Anas Discors ◽  
Food Items ◽  
Anas Clypeata ◽  
Foraging Method ◽  
And Behavior ◽  
Foraging Specialization

This study examined foraging strategies in male Northern Shovelers (Anas clypeata) and Blue-winged Teal (Anas discors). Differences in time–activity budgets and esophageal contents between the two species indicated major differences in the degree of foraging specialization. Preflightless male Northern Shovelers spent 84.2% of time foraging, with dabbling in the water column as the principal foraging mode (83.4%), while postflightless male shovelers spent 81.6% of time foraging (78.7% dabbling). Preflightless male Blue-winged Teal spent 68.6% of time foraging, with dabbling in mud (32.5%) and picking in vegetation (29.4%) as the two principal modes, whereas postflightless male bluewings spent 85.9% of time foraging (dabbling in mud 40.6%, and picking 34.2%). Most male Northern Shoveler food items were cladocerans (85.5%) or chironomid pupae (12.9%); this was related to the specialized foraging method employed by shovelers. Male Blue-winged Teal food items were principally gastropods (44.3%), culicids (29.2%), seeds and vegetation (15.5%), and chironomids (5.6%), which corresponded to the plastic feeding behaviors of bluewings. Examination of esophageal items revealed that male Northern Shovelers did little feeding during the summer flightless period, while male Blue-winged Teal fed throughout the period.

scholarly journals More than Meets the Eye: Functionally Salient Changes in Internal Bone Architecture Accompany Divergence in Cichlid Feeding Mode

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
R. Craig Albertson ◽  
W. James Cooper ◽  
Kenneth A. Mann
Keyword(s):  
Genetic Basis ◽  
Dominant Mode ◽  
Bone Architecture ◽  
Foraging Strategies ◽  
Craniofacial Skeleton ◽  
Suction Feeding ◽  
Foraging Mode ◽  
Feeding Mode ◽  
Adaptive Radiations ◽  
African Cichlids

African cichlids have undergone extensive and repeated adaptive radiations in foraging habitat. While the external morphology of the cichlid craniofacial skeleton has been studied extensively, biomechanically relevant changes to internal bone architecture have been largely overlooked. Here we explore two fundamental questions: (1) Do changes in the internal architecture of bone accompany shifts in foraging mode? (2) What is the genetic basis for this trait? We focus on the maxilla, which is an integral part of the feeding apparatus and an element that should be subjected to significant bending forces during biting. Analyses of μCT scans revealed clear differences between the maxilla of two species that employ alternative foraging strategies (i.e., biting versus suction feeding). Hybrids between the two species exhibit maxillary geometries that closely resemble those of the suction feeding species, consistent with a dominant mode of inheritance. This was supported by the results of a genetic mapping experiment, where suction feeding alleles were dominant to biting alleles at two loci that affect bone architecture. Overall, these data suggest that the internal structure of the cichlid maxilla has a tractable genetic basis and that discrete shifts in this trait have accompanied the evolution of alternate feeding modes.

Food abundance and diet variation in freshwater turtles from the mid-Murray River, Australia

2018 ◽  
Vol 66 (1) ◽  
pp. 67 ◽  
Author(s):  
Kristen Petrov ◽  
Jessica Lewis ◽  
Natasha Malkiewicz ◽  
James U. Van Dyke ◽  
Ricky-John Spencer
Keyword(s):  
Green Algae ◽  
Prey Availability ◽  
Foraging Strategies ◽  
Freshwater Turtles ◽  
Food Items ◽  
Filamentous Green Algae ◽  
Invertebrate Diversity ◽  
Murray River ◽  
Specialist Species ◽  
Chelodina Longicollis

Consumers usually respond to variations in prey availability by altering their foraging strategies. Generalist consumers forage on a diversity of resources and have greater potential to ‘switch’ their diet in response to fluctuations in prey availability, in comparison to specialist consumers. We aimed to determine how the diets of two specialist species (the eastern long-necked turtle (Chelodina longicollis) and the broad-shelled turtle (Chelodina expansa) and the more generalist Murray River short-necked turtle (Emydura macquarii) respond to variation in habitat and prey availability. We trapped and stomach-flushed turtles, and compared their diets along with environmental variables (turbidity, macrophyte and filamentous green algae cover, and aquatic invertebrate diversity and abundance) at four wetlands in north-central Victoria. Diets of E. macquarii differed from those of both Chelodina species, which overlapped, across all four sites. However, samples sizes for the two Chelodina species were too small to compare among-wetland variation in diet. Dietary composition of E. macquarii was variable but did not differ statistically among sites. Emydura macquarii preferentially selected filamentous green algae at three of the four sites. Where filamentous green algae were rare, total food bolus volume was reduced and E. macquarii only partially replaced it with other food items, including other vegetation, wood, and animal prey. Many turtles at these sites also had empty stomachs. Thus, filamentous green algae may be a limiting food for E. macquarii. Although E. macquarii has previously been described as a generalist, it appears to have limited ability to replace filamentous green algae with other food items when filamentous green algae are rare.

scholarly journals A flyway perspective of foraging activity in Eurasian Green-winged Teal, Anas crecca crecca

2007 ◽  
Vol 85 (1) ◽  
pp. 81-91 ◽  
Author(s):  
C. Arzel ◽  
J. Elmberg ◽  
M. Guillemain
Keyword(s):  
Early Spring ◽  
Breeding Strategy ◽  
Foraging Activity ◽  
Long Distance ◽  
Time Activity ◽  
Anas Crecca ◽  
Income Breeding ◽  
Nocturnal Foraging ◽  
Anas Clypeata ◽  
Foraging Time

Time–activity budgets in the family Anatidae are available for the wintering and breeding periods. We present the first flyway-level study of foraging time in a long-distance migrant, the Eurasian Green-winged Teal, Anas crecca crecca L., 1758 (“Teal”). Behavioral data from early and late spring staging, breeding, and molting sites were collected with standardized protocols to explore differences between the sexes, seasons, and diel patterns. Teal foraging activity was compared with that of the Mallard, Anas platyrhynchos L., 1758 and Northern Shoveler, Anas clypeata L., 1758, and the potential effects of duck density and predator-caused disturbance were explored. In early spring, foraging time was moderate (50.5%) and mostly nocturnal (45%). It increased dramatically in all three species at migration stopovers and during molt, mostly because of increased diurnal foraging, while nocturnal foraging remained fairly constant along the flyway. These patterns adhere to the “income breeding” strategy expected for this species. No differences between the sexes were recorded in either species studied. Teal foraging time was positively correlated with density of Teal and all ducks present, but negatively correlated with predator disturbance. Our study suggests that Teal, in addition to being income breeders, may also be considered as income migrants; they find the energy necessary to migrate at staging sites along the flyway.

Prey Selection by Freshwater Predators with Different Foraging Strategies

1985 ◽  
Vol 42 (11) ◽  
pp. 1720-1732 ◽  
Author(s):  
Scott D. Cooper ◽  
Daniel W. Smith ◽  
James R. Bence
Keyword(s):  
Prey Selection ◽  
Foraging Strategies ◽  
Foraging Mode ◽  
Encounter Rates ◽  
Predator Prey ◽  
Anax Junius ◽  
Odonate Larvae ◽  
Selection For ◽  
Predator Foraging ◽  
Pachydiplax Longipennis

We observed several freshwater predators, including the odonate larvae Pachydiplax longipennis and Anax junius, the hemipterans Notonecta unifasciata and Buenoa scimitra, the dytiscid larva Acilius semisulcatus, and juvenile Gambusia affinis, feeding on a variety of microcrustacean prey and determined the frequency of the component parts of predator–prey interactions (encounter, attack, capture, ingestion). Encounter rates were the most important determinant of predator selectivity when predators were presented with a variety of microcrustacean prey. When only copepod species were used as prey, however, both encounter rates and capture success were important in determining predator diets. We used our data to test hypotheses concerning relationships between predator foraging mode and patterns of prey selection: mobile predators exhibited stronger selection for sedentary prey than did sit-and-wait predators; our own and literature data also indicated that macroinvertebrate sit-and-wait predators are better able to capture, and have higher selectivity for evasive prey than do mobile predators. A predator's attack acceleration, however, may be a better predictor of its selectivity for evasive versus nonevasive prey than its mean swimming speed.

scholarly journals Diet and Activity Budget in Colobus angolensis ruwenzorii at Nabugabo, Uganda: Are They Energy Maximizers?

2020 ◽  
pp. 1-20
Author(s):  
T. Jean M. Arseneau-Robar ◽  
Amtul H. Changasi ◽  
Evan Turner ◽  
Julie A. Teichroeb
Keyword(s):  
Food Availability ◽  
Activity Budget ◽  
Foraging Strategies ◽  
High Quality ◽  
Black And White ◽  
Food Items ◽  
Leaf Consumption ◽  
Young Leaves ◽  
Quality Diet ◽  
Colobus Angolensis

<b><i>Introduction:</i></b> Colobine monkeys are specialized folivores that use foregut fermentation to digest leaves. The slow process of fermentation forces them to spend a lot of time resting and to minimize their energy expenditure to subsist on a lower-quality diet. <b><i>Methods:</i></b> We recorded the diet and activity budget of <i>Colobus angolensis ruwenzorii</i>, which form a three-tiered multi-level society, at Lake Nabugabo, Uganda, over 12 months using scan sampling on adults and subadults, to determine whether they utilize the energy minimization strategy typical of colobines. <b><i>Results:</i></b> We found that the annual diet was primarily comprised of high-quality food resources (young leaves 65% and fruit 31%), and fruits were the only plant part the monkeys<i></i>selected when available. Both the fruits and young leaves of some species were preferred food items in some months, and mature leaf consumption correlated negatively with preferred food availability. Mature leaves appear to be a fallback food for this population but are rarely relied upon (3%). The <i>C. a. ruwenzorii</i>at Nabugabo spent less time resting (40%) and more time moving (25%) than is typical for other species of black-and-white colobus. <b><i>Discussion/Conclusion:</i></b> The high-quality diet of this population appears to allow them to utilize an energy maximization strategy. Their reliance on food items that tend to be clumped in space and time likely explains the frequent fission-fusion behaviour that we observe between core units. Our findings demonstrate that the foraging strategies of colobines may be more flexible than was previously thought and illustrate how food availability and distribution can impact primate social organization.

scholarly journals Temporal Flexibility of Reproduction in Temperate-Breeding Dabbling Ducks

The Auk ◽  
2000 ◽  
Vol 117 (3) ◽  
pp. 640-650 ◽  
Author(s):  
Gary L. Krapu
Keyword(s):  
Late Summer ◽  
The United States ◽  
Dabbling Ducks ◽  
Anas Discors ◽  
Interspecific Differences ◽  
Temporal Flexibility ◽  
Anas Clypeata ◽  
Northern Pintails ◽  
Anas Strepera

AbstractI compared nesting intervals during three consecutive years in five species of temperate-nesting dabbling ducks (Mallard [Anas platyrhynchos], Northern Pintail [Anas acuta], Northern Shoveler [Anas clypeata], Blue-winged Teal [Anas discors], Gadwall [Anas strepera]) and assessed whether differences existed in timing of refractoriness. Most nesting by females of all five species ended by the summer solstice. Nesting ended earliest for Northern Shovelers and Northern Pintails and latest for Gadwalls. Some Mallards, Blue-winged Teal, and Gadwalls continued to nest into mid- and late summer, whereas Northern Shovelers and Northern Pintails did not. Mallards, Blue-winged Teal, and Gadwalls accounted for 99% (81 of 82) of flightless broods resulting from nests initiated during mid- or late summer in North Dakota and 98% (58 of 59) of flightless juveniles shot on or after 1 October by a random sample of duck hunters from across the United States. Early cessation of breeding by Northern Shovelers may have evolved in response to the species' limited flexibility in diet. Photorefractory mechanisms that limit most breeding to spring presumably evolved in response to severe constraints on reproductive success when nesting continued through summer (e.g. mortality of late-hatched young and molting females due to low temperatures). Interspecific differences in photosensitivity may account for variation in timing of cessation of nesting in late spring, but controlled experiments are needed to assess the possible role of non-photic influences. My results suggest that the refractory mechanisms controlling length of the breeding season in temperate-nesting dabbling ducks are more varied and complex than previously thought, with non-photic influences (e.g. water conditions, food availability, food quality) having a larger role than indicated by earlier research.

scholarly journals Effects of age and reproductive status on individual foraging site fidelity in a long-lived marine predator

2017 ◽  
Vol 284 (1859) ◽  
pp. 20171068 ◽  
Author(s):  
Stephen C. Votier ◽  
Annette L. Fayet ◽  
Stuart Bearhop ◽  
Thomas W. Bodey ◽  
Bethany L. Clark ◽  
...  
Keyword(s):  
Site Fidelity ◽  
Foraging Strategies ◽  
Common Component ◽  
Small Component ◽  
Phenotypic Differences ◽  
Marine Predator ◽  
Global Positioning ◽  
Foraging Site ◽  
Foraging Ability ◽  
Foraging Specialization

Individual foraging specializations, where individuals use a small component of the population niche width, are widespread in nature with important ecological and evolutionary implications. In long-lived animals, foraging ability develops with age, but we know little about the ontogeny of individuality in foraging. Here we use precision global positioning system (GPS) loggers to examine how individual foraging site fidelity (IFSF), a common component of foraging specialization, varies between breeders, failed breeders and immatures in a long-lived marine predator—the northern gannet Morus bassanus . Breeders (aged 5+) showed strong IFSF: they had similar routes and were faithful to distal points during successive trips. However, centrally placed immatures (aged 2–3) were far more exploratory and lacked route or foraging site fidelity. Failed breeders were intermediate: some with strong fidelity, others being more exploratory. Individual foraging specializations were previously thought to arise as a function of heritable phenotypic differences or via social transmission. Our results instead suggest a third alternative—in long-lived species foraging sites are learned during exploratory behaviours early in life, which become canalized with age and experience, and refined where possible—the exploration-refinement foraging hypothesis. We speculate similar patterns may be present in other long-lived species and moreover that long periods of immaturity may be a consequence of such memory-based individual foraging strategies.

Augerinoichnus Helicoidalis, a new helical trace fossil from the nonmarine Permian of New Mexico

2008 ◽  
Vol 82 (6) ◽  
pp. 1201-1206 ◽  
Author(s):  
Nicholas J. Minter ◽  
Spencer G. Lucas ◽  
Allan J. Lerner ◽  
Simon J. Braddy
Keyword(s):  
New Mexico ◽  
Trace Fossil ◽  
Foraging Strategies ◽  
Lower Permian ◽  
Recent Proposal ◽  
National Monument ◽  
Depositional Settings ◽  
Fossil Assemblages ◽  
Dona Ana County ◽  
And Behavior

New Mexico contains a significant record of trace fossil assemblages, in terms of both abundance and ichnodiversity, from Lower Permian nonmarine depositional settings. Most notable amongst these are the trace fossil assemblages in the Robledo Mountains Formation of the Robledo Mountains in Doña Ana County, southern New Mexico, as recognized by the recent proposal to designate this area as a national monument. These trace fossil assemblages formed on a tidal flat under largely non-marine conditions (Mack and James, 1986; Hunt et al., 1993; Lucas et al., 1995a, 1998) and are dominated by the trackways of tetrapods and arthropods, yielding important information on the paleoecology, diversity and behavior of late Paleozoic arthropods (Braddy and Briggs, 2002; Minter and Braddy, 2006a), as well as evidence of specialized foraging strategies (Minter et al., 2006). Additional Lower Permian trace fossil assemblages occur at a number of localities in New Mexico and represent a variety of nonmarine depositional settings.

scholarly journals In polytocous mammals, weakling neonates, but not their stronger littermates, benefit from specialized foraging

2019 ◽  
Vol 65 (6) ◽  
pp. 675-683 ◽  
Author(s):  
Janko Skok ◽  
Maja Prevolnik Povše
Keyword(s):  
Game Theory ◽  
Growth Rate ◽  
Random Sampling ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Lactation Period ◽  
Common Phenomenon ◽  
Theoretical Predictions ◽  
Foraging Environment ◽  
Foraging Specialization

Abstract Adjusting foraging strategies is a common phenomenon within groups of animals competing for the same resource. In polytocous mammals, neonates concurrently compete for limited milk and alternate between two foraging (suckling) strategies: adaptable exploratory foraging with random sampling of teats, and ordered foraging with a tendency towards exploiting a particular suckling position. Some theoretical (game theory) models have shown that weaker siblings in particular benefit from foraging specialization (suckling order). Neonate piglets establish a well-defined suckling order that develops gradually and fluctuates throughout the lactation period, implying the existence of inter-individual differences in foraging strategies. We therefore analyzed suckling behavior in pigs to determine whether one foraging strategy was more beneficial to neonates in terms of their body weight and foraging environment. We found that intermediate and heavy littermates tended to adjust their suckling strategy according to the foraging environment; however, the selected foraging strategy did not affect their overall growth performance. Lighter individuals that consumed significantly less milk did not greatly alternate their foraging strategy according to the foraging environment, but their growth rate was significantly higher whenever they performed less-exploratory foraging behavior. Although suckling order appeared to be a relatively stable behavioral phenotype, it was beneficial exclusively for weaklings. These results confirm theoretical predictions and indicate that specializing in a suckling position is a beneficial strategy for weaker, light neonates. These findings suggest that physically weaker neonates might have driven the evolution of neonatal foraging specialization.

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