The effect of cover and food on space use by wintering Song Sparrows and Field Sparrows

1997 ◽  
Vol 75 (10) ◽  
pp. 1636-1641 ◽  
Author(s):  
Christopher W. Beck ◽  
Bryan D. Watts
Keyword(s):  
Predation Risk ◽  
Positive Response ◽  
Distribution Patterns ◽  
Microhabitat Use ◽  
Vegetative Cover ◽  
Song Sparrows ◽  
Trade Offs ◽  
Resource Requirements ◽  
Woody Cover ◽  
Species Specific

The distribution of birds among microhabitats may reflect species-specific resource requirements. Both food availability and predation risk have been shown to influence patterns of microhabitat use by sparrows during winter. We investigated the influence of vegetative cover and food on microhabitat use using a 2 × 2 factorial design. Both woody cover and food were manipulated at the plot level. The presence of screening cover (weed stems) was manipulated within plots. Sparrows showed a positive response to the presence of both cover and food. Within plots, sparrows selected areas with screening cover. The distribution of birds between areas with and without screening cover was influenced by the presence of woody cover and food. Conversely, the presence of screening cover reduced the influence of woody cover on the distribution of birds within patches. Song Sparrows (Melospiza melodia) and Field Sparrows (Spizella pusilla) differed in their response to treatments both within and across plots, suggesting that trade-offs between foraging and predation risk may be important in the structuring of winter sparrow assemblages. Additionally, screening cover appears to moderate predation risk and therefore to affect distribution patterns.

scholarly journals Microhabitat Use Affects Brain Size and Structure in Intertidal Gobies

2015 ◽  
Vol 85 (2) ◽  
pp. 107-116 ◽  
Author(s):  
Gemma E. White ◽  
Culum Brown
Keyword(s):  
Spatial Learning ◽  
Brain Size ◽  
Microhabitat Use ◽  
Rocky Shores ◽  
Rock Pool ◽  
Environmental Complexity ◽  
Learning Abilities ◽  
Trade Offs ◽  
Species Specific ◽  
Dorsal Medulla

The ecological cognition hypothesis poses that the brains and behaviours of individuals are largely shaped by the environments in which they live and the associated challenges they must overcome during their lives. Here we examine the effect of environmental complexity on relative brain size in 4 species of intertidal gobies from differing habitats. Two species were rock pool specialists that lived on spatially complex rocky shores, while the remainder lived on dynamic, but structurally simple, sandy shores. We found that rock pool-dwelling species had relatively larger brains and telencephalons in particular, while sand-dwelling species had a larger optic tectum and hypothalamus. In general, it appears that various fish species trade off neural investment in specific brain lobes depending on the environment in which they live. Our previous research suggests that rock pool species have greater spatial learning abilities, enabling them to navigate their spatially complex environment, which may account for their enlarged telencephalon, while sand-dwelling species likely have a reduced need for spatial learning, due to their spatially simple habitat, and a greater need for visual acuity. The dorsal medulla and cerebellum size was unaffected by the habitat in which the fish lived, but there were differences between species indicative of species-specific trade-offs in neural investment.

Co-occurring Notonecta (Hemiptera: Heteroptera: Notonectidae) Species Differ in Their Behavioral Response to Cues of Belostoma (Hemiptera: Heteroptera: Belostomatidae) Predation Risk

2019 ◽  
Vol 112 (4) ◽  
pp. 402-408
Author(s):  
Ilia Maria C Ferzoco ◽  
Celina B Baines ◽  
Shannon J McCauley
Keyword(s):  
Predation Risk ◽  
Chemical Cues ◽  
Habitat Specialization ◽  
Life History Strategies ◽  
Generalist Species ◽  
Ephemeral Ponds ◽  
Trade Offs ◽  
Specialist Species ◽  
Species Specific ◽  
Shared Predator

Abstract Predators affect prey through direct consumption as well as by inducing prey to defensively alter their phenotypes, including behavioral phenotypes, to maximize survival under predation risk. Closely related sympatric prey species with shared natural enemies may resolve behavioral trade-offs under predation risk differently. In a laboratory experiment, we investigated two co-occurring semiaquatic backswimmer congeners, which exhibit differences in their degree of habitat specialization across a gradient of habitat permanence. Notonecta irrorata Uhler primarily occur in ephemeral ponds, whereas Notonecta undulata Say are habitat generalists that are commonly found in both permanent and ephemeral ponds. We tested whether the two species differed in antipredator responses to both visual and chemical cues of a shared predator, the giant water bug, in a fully factorial design. The generalist species, N. undulata, exhibited reductions in activity in the presence of predator chemical cues only, whereas the specialist species, N. irrorata, remained consistently active across predator cue treatments. Our work shows that there are species-specific differences in how prey assess or respond to predation risk. The varying propensities of these backswimmer congeners to behaviorally respond to a shared predator, and differences in their behavior when exposed to different predation risk cues may be linked to underlying divergence in their life-history strategies.

scholarly journals Biomass and nitrogen distribution ratios reveal a reduced root investment in temperate lianas vs. self-supporting plants

2019 ◽  
Vol 124 (5) ◽  
pp. 777-790 ◽  
Author(s):  
Tomasz P Wyka ◽  
Marcin Zadworny ◽  
Joanna Mucha ◽  
Roma Żytkowiak ◽  
Kinga Nowak ◽  
...  
Keyword(s):  
Plant Biomass ◽  
Unit Length ◽  
Resource Distribution ◽  
Distribution Patterns ◽  
External Support ◽  
Life Strategy ◽  
Unit Leaf ◽  
Trade Offs ◽  
Ontogenetic Drift ◽  
Species Specific

Abstract Background and Aims The reliance on external support by lianas has been hypothesized to imply a reduction in the biomass cost of stem construction and root anchorage, and an increased investment in leaves, relative to self-supporting plants. These evolutionary trade-offs have not been adequately tested in an ontogenetic context and on the whole-plant scale. Moreover, the hypothesis may be extended to other potentially limiting resources, such as nitrogen (N.) Methods Plants belonging to five con-familiar pairs of temperate liana/shrub species were cultivated in 120 L barrels and sequentially harvested over up to three growing seasons. To account for the ontogenetic drift, organ biomass and nitrogen fractions were adjusted for plant biomass and N pool, respectively. Key Results Lianas invested, on average, relatively less biomass in the root fraction in comparison with shrubs. This was offset by only insignificant increases in leaf or stem investment. Even though liana stems and roots showed higher N concentration in comparison with shrubs, plant N distribution was mostly driven by, and largely matched, the pattern of biomass distribution. Lianas also showed a greater relative growth rate than shrubs. The differences between the growth forms became apparent only when ontogenetic drift was controlled for. These results were confirmed regardless of whether reproductive biomass was included in the analysis. Conclusions Our results suggest that temperate lianas, in spite of their diverse, species-specific resource distribution patterns, preferentially allocate resources to above-ground organs at the expense of roots. By identifying this trade-off and demonstrating the lack of a general trend for reduction in stem investment in lianas, we significantly modify the prevailing view of liana allocation strategies and evolutionary advantages. Such a resource distribution pattern, along with the cheap unit leaf area and stem unit length construction, situates lianas as a group close to the fast acquisition/rapid growth end of the life strategy spectrum.

scholarly journals Microhabitat of small mammals at ground and understorey levels in a deciduous, southern Atlantic Forest

2013 ◽  
Vol 85 (2) ◽  
pp. 727-736 ◽  
Author(s):  
GERUZA L. MELO ◽  
BARBARA MIOTTO ◽  
BRISA PERES ◽  
NILTON C. CACERES
Keyword(s):  
Habitat Selection ◽  
Small Mammals ◽  
Strong Evidence ◽  
Animal Species ◽  
Deciduous Forest ◽  
Distribution Patterns ◽  
Microhabitat Use ◽  
Southern Brazil ◽  
Different Types ◽  
Didelphis Albiventris

Each animal species selects specific microhabitats for protection, foraging, or micro-climate. To understand the distribution patterns of small mammals on the ground and in the understorey, we investigated the use of microhabitats by small mammals in a deciduous forest of southern Brazil. Ten trap stations with seven capture points were used to sample the following microhabitats: liana, fallen log, ground litter, terrestrial ferns, simple-trunk tree, forked tree, and Piper sp. shrubs. Seven field phases were conducted, each for eight consecutive days, from September 2006 through January 2008. Four species of rodents (Akodon montensis, Sooretamys angouya, Oligoryzomys nigripes and Mus musculus) and two species of marsupials (Didelphis albiventris and Gracilinanus microtarsus) were captured. Captured species presented significant differences on their microhabitat use (ANOVA, p = 0.003), particularly between ground and understorey sites. Akodon montensis selected positively terrestrial ferns and trunks, S. angouya selected lianas, D. albiventris selected fallen trunks and Piper sp., and G. microtarsus choose tree trunks and lianas. We demonstrated that the local small-mammal assemblage does select microhabitats, with different types of associations between species and habitats. Besides, there is a strong evidence of habitat selection in order to diminish predation.

scholarly journals Living in mixed species groups promotes predator learning in degraded habitats

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Douglas P. Chivers ◽  
Mark I. McCormick ◽  
Eric P. Fakan ◽  
Randall P. Barry ◽  
Maud C. O. Ferrari
Keyword(s):  
Predation Risk ◽  
Abiotic Factors ◽  
Alarm Cues ◽  
Learning Mechanisms ◽  
Trade Offs ◽  
Chemical Alarm Cues ◽  
Pomacentrus Amboinensis ◽  
Predator Foraging ◽  
Predator Learning ◽  
Predator Odour

AbstractLiving in mix-species aggregations provides animals with substantive anti-predator, foraging and locomotory advantages while simultaneously exposing them to costs, including increased competition and pathogen exposure. Given each species possess unique morphology, competitive ability, parasite vulnerability and predator defences, we can surmise that each species in mixed groups will experience a unique set of trade-offs. In addition to this unique balance, each species must also contend with anthropogenic changes, a relatively new, and rapidly increasing phenomenon, that adds further complexity to any system. This complex balance of biotic and abiotic factors is on full display in the exceptionally diverse, yet anthropogenically degraded, Great Barrier Reef of Australia. One such example within this intricate ecosystem is the inability of some damselfish to utilize their own chemical alarm cues within degraded habitats, leaving them exposed to increased predation risk. These cues, which are released when the skin is damaged, warn nearby individuals of increased predation risk and act as a crucial associative learning tool. Normally, a single exposure of alarm cues paired with an unknown predator odour facilitates learning of that new odour as dangerous. Here, we show that Ambon damselfish, Pomacentrus amboinensis, a species with impaired alarm responses in degraded habitats, failed to learn a novel predator odour as risky when associated with chemical alarm cues. However, in the same degraded habitats, the same species learned to recognize a novel predator as risky when the predator odour was paired with alarm cues of the closely related, and co-occurring, whitetail damselfish, Pomacentrus chrysurus. The importance of this learning opportunity was underscored in a survival experiment which demonstrated that fish in degraded habitats trained with heterospecific alarm cues, had higher survival than those we tried to train with conspecific alarm cues. From these data, we conclude that redundancy in learning mechanisms among prey guild members may lead to increased stability in rapidly changing environments.

scholarly journals MULTI-CLASS RESOURCE SHARING WITH BATCH ARRIVALS

2018 ◽  
Vol 33 (3) ◽  
pp. 348-366
Author(s):  
Paul Ezhilchelvan ◽  
Isi Mitrani
Keyword(s):  
Resource Sharing ◽  
Large Scale ◽  
Virtual Machines ◽  
Cloud Provider ◽  
Batch Arrivals ◽  
Large Scale Systems ◽  
Trade Offs ◽  
Resource Requirements ◽  
Partial Blocking ◽  
Fixed Point Iterations

A cloud provider hosts virtual machines (VMs) of different types, with different resource requirements. There are bounds on the total amounts of each kind of resource that are available. Requests arrive in batches of different sizes. Under the ‘complete blocking’ policy, a request is accepted only if all the VMs in its batch can be accommodated. The ‘partial blocking’ policy would accept a request if there is room for at least one of the VMs in the batch. Blocked requests are lost, with an associated loss of revenue. The trade-offs between costs and benefits are evaluated by means of appropriate models, for which novel solutions based on fixed-point iterations are proposed. The applicability of those solutions is extended, by means of simplifications, to very large-scale systems. Numerical examples and comparisons with simulations are presented.

Grenadiers of the World Oceans: Biology, Stock Assessment, and Fisheries

2008 ◽  
Keyword(s):  
Stock Assessment ◽  
Distribution Patterns ◽  
Abundant Species ◽  
Trawl Survey ◽  
Bathymetric Range ◽  
Main Species ◽  
The World ◽  
Species Specific ◽  
Depth Ranges ◽  
Preanal Length

<em>Abstract</em>.—The objective of this study is to describe the distribution patterns of abundance and biomass, on a geographic and bathymetric basis, of the main macrourid species of Mozambique waters. Catch data from a demersal trawl survey (<EM>MOZAMBIQUE 07</EM>) were analyzed. The survey covered the continental shelf and upper-middle slope from 17°00’S to 26°50’S and from 100–700 m depth. Fourteen macrourid species were collected from 200 m and deeper. The most abundant species and the highest in biomass were <em>Coelorinchus braueri</em>, <em>C. trunovi, C. denticulatus</em>, <em>Ventrifossa nasuta</em>, and <em>Malacocephalus laevis</em>. Only those five species were analyzed in detail. The occurrence and yields by geographic and bathymetric range of these main species seem to reveal the existence of some species-specific preference for determinate depth ranges and/or geographic areas. Preanal length-weight relationships were estimated for <em>C. braueri, C. trunovi, </em>and <em>V. nasuta</em>: <em>a</em>= 0.00071; 0.00020; 0.00080; <em>b</em>= 2.50; 2.80; 2.76 and <em>r</em><sup>2</sup>= 0.93; 0.97; 0.78, respectively.

Evaluating trade-offs between forage, biting flies, and footing on habitat selection by wood bison (Bison bison athabascae)

2020 ◽  
Vol 98 (4) ◽  
pp. 254-261
Author(s):  
R.J. Belanger ◽  
M.A. Edwards ◽  
L.N. Carbyn ◽  
S.E. Nielsen
Keyword(s):  
Habitat Selection ◽  
Environmental Factors ◽  
Predation Risk ◽  
Bison Bison ◽  
Winter Habitat ◽  
Forage Availability ◽  
Trade Offs ◽  
Wood Bison ◽  
Insect Harassment ◽  
Biting Fly

Habitat selection is a behavioural process that ultimately affects animal fitness. Forage availability and predation risk are often studied in the context of habitat selection for large ungulates, while other biological and environmental factors such as insect harassment and footing are less studied. Here we examine trade-offs in summer habitat selection between forage availability for wood bison (Bison bison athabascae Rhoads, 1898) with that of biting-fly harassment and soil firmness, which affects activity budgets and predation risk, respectively, and contrast this to winter when flies are absent and soils frozen. Using path analysis, we demonstrate that graminoid availability was not related to habitat selection in summer, but was positively related to habitat selection in winter. Habitat selection in summer was negatively related to biting-fly abundance and positively related to firmer footing. Our results suggest that bison observe trade-offs in summer between maximizing forage intake and minimizing harassment from that of biting flies, while avoiding areas of soft substrates that affect locomotion and vulnerability to predators. In contrast, during the winter, bison focus on areas with greater graminoid availability. Although forage is a key aspect of habitat selection, our results illustrate the importance of considering direct and indirect effects of multiple biological and environmental factors related to ungulate habitat selection.

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