Predation on simulated duck nests in relation to nest density and landscape structure

2010 ◽  
Vol 37 (7) ◽  
pp. 597 ◽  
Author(s):  
Eliška Padyšáková ◽  
Martin Šálek ◽  
Lukáš Poledník ◽  
František Sedláček ◽  
Tomáš Albrecht
Keyword(s):  
Survival Rates ◽  
Predation Rate ◽  
High Density ◽  
Nest Density ◽  
Predator Species ◽  
Density Dependent ◽  
Landscape Type ◽  
Mammalian Predators ◽  
Littoral Vegetation ◽  
Nest Predator

Context Density-dependent predation has been recently discussed as a contributing cause of duck nest failure. Aims We tested whether nest density increases the nest predation rate (density-dependent predation) in patches of littoral vegetation surrounding fishponds in two contrasting landscape types, the first dominated by forest and the other dominated by agricultural fields. Methods In total, 576 simulated ground nests were deployed in 48 littoral patches in South Bohemia, Czech Republic, in two replicates (June and July), for two consecutive years (2005 and 2006). Nests were deployed either solitarily (low-density plots) or in groups of five nests (high-density plots). Key results Despite differences in local predator communities, we found no evidence of different survival rates of solitary nests and nests placed in high-density patches in either habitat. Mammalian predators were the most common nest predators, followed by birds. The composition of nest predator community depended on landscape type, with mammals predominating in forest landscape and birds in agricultural areas. Our data thus do not support the theory of density-dependent predation of duck nests in littoral patches, regardless of predominant nest predator type. Conclusions Based on our results, we conclude that nest predator responses to different habitats are complex, taxon specific, and context dependent. Implications Conservation efforts for waterfowl may need to be customised according to the nest-predator species primarily responsible for local nest mortality and the nature of the landscape mosaic.

scholarly journals Do Repugnant Scents Increase Survival of Ground Nests? A Test with Artificial and Natural Duck Nests

2007 ◽  
Vol 121 (2) ◽  
pp. 150
Author(s):  
Vanessa B. Harriman ◽  
Justin A. Pitt ◽  
Serge Larivière
Keyword(s):  
Human Hair ◽  
Nest Predation ◽  
Survival Rates ◽  
Olfactory Cues ◽  
Artificial Nests ◽  
Treatment Groups ◽  
Mammalian Predators ◽  
High Predation ◽  
Ground Nesting ◽  
Predation Rates

Ground-nesting birds typically experience high predation rates on their nests, often by mammalian predators. As such, researchers and wildlife managers have employed numerous techniques to mitigate nest predation. We investigated the use of scents as repellents to deter predators from both artificial and natural ground nests. Survival rates of artificial nests did not differ among six groups of substances (Wald ?2 df = 5 = 4.53, P < 0.48); however the chronology of predation among groups differed. A commercial Coyote urine based deterrent (DEER-D-TERTM), human hair, and Worcestershire sauce were depredated faster than the control (F4,5 = 40.3, P < 0.001). Nest survival of natural nests differed among those groups tested (Wald ?2 df = 2 = 11.8, P < 0.005); the eight mothball treatment decreased survival (Wald ?2 df = 1 = 11.5, P < 0.005), which indicated that novel smells may attract predators or result in duck nest abandonment when coupled with natural duck scent. Chronologies of predation events among treatment groups were not different for natural nests (F2,3 = 1.9, P = 0.22). These findings indicate an interaction between novel scents and predator olfactory cues.

scholarly journals DENSITY-DEPENDENT PHONORITON STATES IN HIGHLY EXCITED SEMICONDUCTORS

1995 ◽  
Vol 09 (28) ◽  
pp. 3725-3733
Author(s):  
NGUYEN HONG QUANG ◽  
NGUYEN MINH KHUE
Keyword(s):  
Green's Function ◽  
Random Phase Approximation ◽  
Function Method ◽  
Random Phase ◽  
High Density ◽  
Phase Approximation ◽  
Green’S Function Method ◽  
Exciton Density ◽  
Density Dependent ◽  
Exciton Interaction

The dynamical aspects of the phonoriton state in highly-photoexcited semiconductors is studied theoretically. The effect of the exciton–exciton interaction and nonbosonic character of high-density excitons are taken into account. Using Green's function method and within the Random Phase Approximation it is shown that the phonoriton dispersion and damping are very sensitive to the exciton density, characterizing the excitation degree of semiconductors.

scholarly journals Transgenerational effects modulate density-dependent prophylactic resistance to viral infection in a lepidopteran pest

2015 ◽  
Vol 11 (3) ◽  
pp. 20150012 ◽  
Author(s):  
Kenneth Wilson ◽  
Robert I. Graham
Keyword(s):  
Disease Resistance ◽  
Survival Rates ◽  
Post Challenge ◽  
Transgenerational Effects ◽  
Density Dependent ◽  
Offspring Fitness ◽  
Rearing Density ◽  
Lepidopteran Pest ◽  
The Impact ◽  
Resistance To Viral Infection

There is an increasing appreciation of the importance of transgenerational effects on offspring fitness, including in relation to immune function and disease resistance. Here, we assess the impact of parental rearing density on offspring resistance to viral challenge in an insect species expressing density-dependent prophylaxis (DDP); i.e. the adaptive increase in resistance or tolerance to pathogen infection in response to crowding. We quantified survival rates in larvae of the cotton leafworm ( Spodoptera littoralis ) from either gregarious- or solitary-reared parents following challenge with the baculovirus S. littoralis nucleopolyhedrovirus. Larvae from both the parental and offspring generations exhibited DDP, with gregarious-reared larvae having higher survival rates post-challenge than solitary-reared larvae. Within each of these categories, however, survival following infection was lower in those larvae from gregarious-reared parents than those from solitary-reared, consistent with a transgenerational cost of DDP immune upregulation. This observation demonstrates that crowding influences lepidopteran disease resistance over multiple generations, with potential implications for the dynamics of host–pathogen interactions.

DENSITY-DEPENDENT FERTILITY SELECTION IN EXPERIMENTAL POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1981 ◽  
Vol 98 (4) ◽  
pp. 849B-869
Author(s):  
Andrew G Clark ◽  
Marcus W Feldman
Keyword(s):  
Drosophila Melanogaster ◽  
Development Time ◽  
Wing Length ◽  
Larval Density ◽  
High Density ◽  
Density Dependent ◽  
Resource Limited ◽  
Adult Body ◽  
Adult Body Weight ◽  
Mutant Lines

ABSTRACT The effects of larval density on components of fertility fitness were investigated with two mutant lines of Drosophila melanogaster. The differences in adult body weight, wing length, larval survivorship and development time verified that flies reared at high density were resource limited. Experimental results indicate that: (1) relative fecundities of both sexes show density-dependent effects, (2) there is a strong density effect on male and female mating success, and (3) in general, there is a reduction in fecundity differences between genotypes at high density. These results imply that it may be important to consider fertility in models of density-dependent natural selection.

scholarly journals Arboreal aperitifs: Space use and activity of a major songbird nest predator in a tropical Thailand forest

2021 ◽  
Author(s):  
Anji D’souza ◽  
George Gale ◽  
Benjamin Michael Marshall ◽  
Daphawan Khamcha ◽  
Surachit Waengsothorn ◽  
...  
Keyword(s):  
Brownian Bridge ◽  
Radio Telemetry ◽  
Space Use ◽  
Evergreen Forest ◽  
Boiga Irregularis ◽  
Forest Fragment ◽  
Predator Species ◽  
Avian Nest ◽  
Nest Predator ◽  
Nesting Season

ABSTRACTPredator-prey interactions are fundamental drivers of population dynamics, yet rarely are both predator and prey species simultaneously studied. Despite being significant, widespread avian nest predators, research on the ecology of Southeast Asian snakes in relation to birds remains scarce. The green cat snake (Boiga cyanea) is a primary nest predator, responsible for ≈24% of forest songbird depredation in Northeast Thailand. We explored both diurnal and nocturnal movements of 14 (5 male, 9 female) adult B. cyanea with radio-telemetry for an average of 68 ± 16 days per individual, between 21 October 2017 and 8 June 2019 in the dry evergreen forest of the Sakaerat Biosphere Reserve (SBR). We quantified area of space use (ha) and activity through motion variance (Ϭm2) during the study period using dynamic Brownian bridge movement models, and linked our findings to a simultaneously-run avian nest monitoring study, initiated in 2013 within the same forest fragment. On average, movements, space use and activity differed between males and females, and between the avian nesting and non-nesting seasons. Males moved 51.37 m/day farther than females. They used areas 15.09 ha larger than females, and their activity was 3.91 Ϭm2 higher than that of females. In general, individuals moved 50.30 m/day farther during the nesting season than the non-nesting season. The snakes used areas 9.84 ha larger during the nesting season than the non-nesting season, and their activity during the nesting season was 3.24 Ϭm2 higher than that during the non-nesting season. All individuals were exclusively nocturnal, moving throughout the night, and often descending from higher diurnal refugia (>2 m) to forage closer to the ground after sunset. Boiga cyanea activity followed a similar trend to that of the recorded nest depredations at SBR. Our study links snake activity to nest depredations in SBR. Our openly-available data may yield further insight when combined with other major avian nest predator species like the congeneric invasive brown tree snake (Boiga irregularis) on the island of Guam.

Burrow occupancy and productivity at coastal sooty shearwater (Puffinus griseus) breeding colonies, South Island, New Zealand: can mark - recapture be used to estimate burrowscope accuracy?

2003 ◽  
Vol 30 (4) ◽  
pp. 377 ◽  
Author(s):  
Chris Jones ◽  
Susan Bettany ◽  
Henrik Moller ◽  
David Fletcher ◽  
Justine de Cruz
Keyword(s):  
New Zealand ◽  
Survival Rates ◽  
Species Abundance ◽  
Adult Survival ◽  
Egg Survival ◽  
Global Pattern ◽  
Data Set ◽  
Mark Recapture ◽  
Mammalian Predators ◽  
Occupancy Rates

Breeding colonies of sooty shearwaters ('muttonbird', tïtï, Puffinus griseus) on mainland New Zealand have declined in recent years. New data on burrow occupancy and colony productivity for seven sooty shearwater breeding colonies on the coast of Otago, New Zealand for the 1996–97 and 1997–98 breeding seasons are presented and analysed as part of a five-year data set. Detection of a burrow's occupants using a fibre-optic burrowscope may underestimate absolute occupancy rates, but is still of value in the analysis of trends. Detection probabilities estimated by the novel use of mark–recapture models corresponded with those of previous studies of the technique's accuracy. Mainland declines are associated with a lack of control of introduced mammalian predators at most mainland colonies superimposed on a global pattern of decline in the species' abundance. Large numbers of recovered carcasses and an absence of burrow activity at two small mainland colonies show the decline to extinction of these colonies over the five years of collecting data. At one mainland colony with intensive predator control, survival rates and parameter variances are comparable with those found on a predator-free offshore island. All other mainland colonies showed negligible breeding success. There was a significant positive relationship between egg survival and an index of relative adult survival, with an apparent threshold below which few eggs hatch. Adult survival during the breeding season is likely to be the most important parameter in maintaining a colony's viability.

scholarly journals Intra-guild vs extra-guild prey: effect on predator fitness and preference of Amblyseius swirskii (Athias-Henriot) and Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae)

2009 ◽  
Vol 100 (2) ◽  
pp. 167-173 ◽  
Author(s):  
R. Buitenhuis ◽  
L. Shipp ◽  
C. Scott-Dupree
Keyword(s):  
Frankliniella Occidentalis ◽  
Western Flower Thrips ◽  
Predation Rate ◽  
Predatory Mites ◽  
Amblyseius Swirskii ◽  
Neoseiulus Cucumeris ◽  
Predator Species ◽  
Flower Thrips ◽  
Fast Development ◽  
High Predation Rate

AbstractThe relationships between the predatory mites, Amblyseius swirskii (Athias-Henriot) and Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), and their prey, western flower thrips (Frankliniella occidentalis Pergande) (Thysanoptera: Thripidae), were investigated to determine the effects of predation on intra-guild or extra-guild prey and predator preference. Life history characteristics of both predatory mites were measured when fed eggs and larvae of the other predator species and compared to data obtained when the predators were fed thrips larvae. In addition, choice tests were conducted to determine if the predators had a preference for different prey or if they were indiscriminate predators. Amblyseius swirskii appears to be an important intra-guild predator of N. cucumeris juveniles because of a high predation rate and a preference for N. cucumeris juveniles over thrips. Neoseiulus cucumeris is also an intra-guild predator of A. swirskii juveniles; however, it has a lower predation rate than A. swirskii. Contrary to intra-guild predation theory, intra-guild prey was an equally good or better food source than thrips (extra-guild prey) for both predators, based on high oviposition rates and fast development times. The results of this study indicate a high potential for negative interactions between A. swirskii and N. cucumeris when used together in biological control of thrips.

Bounds on the Optimal Age-at-First-Capture for Stochastic, Age-Structured Fisheries

1986 ◽  
Vol 43 (1) ◽  
pp. 101-107 ◽  
Author(s):  
William S. Lovejoy
Keyword(s):  
Lower Bound ◽  
Stochastic Dynamics ◽  
Survival Rates ◽  
Sufficient Conditions ◽  
Optimal Management ◽  
Density Dependent ◽  
Management Regime ◽  
Dependent Model ◽  
Critical Age ◽  
Age Structured

This paper addresses the problem of optimally exploiting an age-structured fishery with stochastic, density-dependent recruitment; stochastic dynamics; and cohort-dependent prices, costs, catchabilities, and survival rates. Sufficient conditions are derived for an age-at-first-capture to be a necessary component of the optimal management regime, and a lower bound on this critical age is calculated. The method consists of replacing the stochastic, density-dependent model with more traditional (stochastic, density-independent and deterministic, density-independent) models which yield lower bounds on the optimal escapement. A numerical example demonstrates the practical applicability of the results.

scholarly journals Interspecific density-dependent model of predator–prey relationship in the chemostat

2020 ◽  
pp. 2050086
Author(s):  
Tahani Mtar ◽  
Radhouane Fekih-Salem ◽  
Tewfik Sari
Keyword(s):  
Three Dimensional ◽  
Steady States ◽  
Dimensional System ◽  
Planar System ◽  
Predator Species ◽  
Predator Prey ◽  
Density Dependent ◽  
Existence And Stability ◽  
Dependent Growth ◽  
Transcritical Bifurcations

The objective of this study is to analyze a model of competition for one resource in the chemostat with general interspecific density-dependent growth rates, taking into account the predator–prey relationship. This relationship is characterized by the fact that the prey species promotes the growth of the predator species which in turn inhibits the growth of the first species. The model is a three-dimensional system of ordinary differential equations. With the same dilution rates, the model can be reduced to a planar system where the two models have the same local and even global behavior. The existence and stability conditions of all steady states of the reduced model in the plane are determined according to the operating parameters. Using the nullcline method, we present a geometric characterization of the existence and stability of all equilibria showing the multiplicity of coexistence steady states. The bifurcation diagrams illustrate that the steady states can appear or disappear only through saddle-node or transcritical bifurcations. Moreover, the operating diagrams describe the asymptotic behavior of this system by varying the control parameters and show the effect of the inhibition of predation on the emergence of the bistability region and the reduction until the disappearance of the coexistence region by increasing this inhibition parameter.

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