Caching Behaviour in the Gray Jay and the Source-Departure Decision for Rate-Maximizing Scatterhoarders

Behaviour ◽  
1992 ◽  
Vol 120 (1-2) ◽  
pp. 51-67 ◽  
Author(s):  
Thomas A. Waite ◽  
John D. Reeve
Keyword(s):  
Average Rate ◽  
Food Sources ◽  
Single Source ◽  
Departure Point ◽  
Departure Decision ◽  
Gray Jays ◽  
Perisoreus Canadensis ◽  
Apparent Violation ◽  
Multiple Load

AbstractWe developed a model that concerns, in part, how long a scatterhoarder should persist in caching food from an ephemeral, locally abundant source ('bonanza') before moving on in search of other sources. The model assumes that an animal scattering food caches for later use behaves in a manner that maximizes the rate at which it stores recoverable (surviving) food in its habitat. It is shown theoretically that under some conditions it is better not to cache all available food but instead to move on in search of other food sources. This 'source-departure decision' for scatterhoarders is analogous to the patch-departure decision for animals that forage among food patches. It is shown that whether, and at what point, a 'moving-on threshold' is reached should depend on the size of the source, the strength of density-dependent cache theft, and the abundance of sources in the habitat. A field experiment was performed to test the qualitative prediction that gray jays, Perisoreus canadensis, should not persist as long in caching food when a day-long opportunity for caching is restricted to a single source (single-source treatment) as when such an opportunity is divided among a series of disjunct sources (multiple-source treatment). In the single-source treatment, jays tended to cache at lower overall rates, transport food items to more distant cache sites, and spend less time caching. These tendencies became more pronounced later in the day. However, although the rate of caching approached zero in the single-source treatment, the jays did not completely cease caching. This apparent violation of the model is attributed to the behaviour of recaching, a facet of gray jay scatterhoarding behaviour that was not built into the model. This retrieval and redistribution of previous caches resulted in the stabilization of the density of caches near the source. In addition, this switch from single- to multiple-load caching trips arguably would make it economical for gray jays to continue to make caching trips from a source beyond the source-departure point predicted by the model. Our theoretical and empirical results begin to show how scatterhoarders may behave in a manner that maximizes the long-term average rate of storage of recoverable food energy throughout their habitat.

Long-term data indicates that supplementary food enhances the number of breeding pairs in a Cape Vulture Gyps coprotheres colony

2016 ◽  
Vol 27 (1) ◽  
pp. 140-152 ◽  
Author(s):  
DANA G. SCHABO ◽  
SONJA HEUNER ◽  
MICHAEL V. NEETHLING ◽  
SASCHA RÖSNER ◽  
ROGER UYS ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Breeding Success ◽  
Food Sources ◽  
Breeding Colony ◽  
Supplementary Food ◽  
Adequate Food ◽  
Vulture Conservation ◽  
Positive Effect ◽  
Term Data

SummaryThe number of vultures is declining in many parts of the world due to numerous threats, such as poisoning and collisions with power-lines as well as the lack of adequate food sources. Vulture restaurants, i.e. supplementary feeding stations, have become a widespread conservation tool aimed at supporting vulture colonies. However, it is poorly understood how vulture restaurants influence population dynamics and whether they affect breeding success of vulture populations. We used a 12-year dataset from a breeding colony of the Cape Vulture Gyps coprotheres and a nearby vulture restaurant in South Africa to investigate the effect of supplementary food on population dynamics and breeding success. We found a significantly positive effect of supplementary food during the nest-building stage on the number of breeding pairs. However, breeding success, i.e. the proportion of successful nests, did not depend on supplementary food during the incubation and rearing stage. Especially during the critical rearing stage, the amount of food supplied might not have been sufficient to meet food demands of the colony. Still, our results indicate that carefully managed vulture restaurants might stabilise vulture colonies and can therefore aid vulture conservation.

scholarly journals Long-Term Projections of the Natural Expansion of the Pine Wood Nematode in the Iberian Peninsula

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 849
Author(s):  
Begoña de la Fuente ◽  
Santiago Saura
Keyword(s):  
Iberian Peninsula ◽  
Tree Species ◽  
Average Rate ◽  
Limiting Factor ◽  
Pine Wood Nematode ◽  
Individual Tree ◽  
Pine Wood ◽  
Pine Tree ◽  
Informative Content

The invasive pine wood nematode (PWN), Bursaphelenchus xylophilus, causal agent of pine wilt disease, was first reported in Europe, near Lisbon, in 1999, and has since then spread to most of Portugal. We here modelled the spatiotemporal patterns of future PNW natural spread in the Iberian Peninsula, as dispersed by the vector beetle Monochamus galloprovincialis, using a process-based and previously validated network model. We improved the accuracy, informative content, forecasted period and spatial drivers considered in previous modelling efforts for the PWN in Southern Europe. We considered the distribution and different susceptibility to the PWN of individual pine tree species and the effect of climate change projections on environmental suitability for PWN spread, as we modelled the PWN expansion dynamics over the long term (>100 years). We found that, in the absence of effective containment measures, the PWN will spread naturally to the entire Iberian Peninsula, including the Pyrenees, where it would find a gateway for spread into France. The PWN spread will be relatively gradual, with an average rate of 0.83% of the total current Iberian pine forest area infected yearly. Climate was not found to be an important limiting factor for long-term PWN spread, because (i) there is ample availability of alternative pathways for PWN dispersal through areas that are already suitable for the PWN in the current climatic conditions; and (ii) future temperatures will make most of the Iberian Peninsula suitable for the PWN before the end of this century. Unlike climate, the susceptibility of different pine tree species to the PWN was a strong determinant of PWN expansion through Spain. This finding highlights the importance of accounting for individual tree species data and of additional research on species-specific susceptibility for more accurate modelling of PWN spread and guidance of related containment efforts.

scholarly journals Hurricanes as a Major Driver of Coastal Erosion in the Mississippi River Delta: A Multi-Decadal Analysis of Shoreline Retreat Rates at Bay Champagne, Louisiana (USA)

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1480 ◽  
Author(s):  
Marianne Dietz ◽  
Kam-biu Liu ◽  
Thomas Bianchette
Keyword(s):  
Mississippi River ◽  
Average Rate ◽  
Landsat Imagery ◽  
Mississippi River Delta ◽  
Coastal Lake ◽  
Shoreline Retreat ◽  
The Past ◽  
Coastal Features ◽  
Mexico Coast

The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few decades. A section of the Louisiana (USA) coast that has one of the highest rates of shoreline retreat in North America is the Caminada-Moreau headland, located south of New Orleans. Bay Champagne is a coastal lake within the headland that provides a unique opportunity to investigate shoreline retreat and the coastal effects of hurricanes. In order to examine the influence of hurricanes on the rate of shoreline retreat, 35 years (1983–2018) of Landsat imagery was analyzed. During that period of time, the shoreline has retreated 292 m. The overall rate of shoreline retreat, prior to a beach re-nourishment project completed in 2014, was over 12 m per year. A period of high hurricane frequency (1998–2013) corresponds to an increased average shoreline retreat rate of >21 m per year. Coastal features created by multiple hurricanes that have impacted this site have persisted for several years. Bay Champagne has lost 48% of its surface area over the last 35 years as a result of long-term shoreline retreat. If shoreline retreat continues at the average rate, it is expected that Bay Champagne will disappear completely within the next 40 years.

Erroneous choice and foregone gains in hoarding gray jays ( Perisoreus canadensis )

2000 ◽  
Vol 3 (3) ◽  
pp. 127-134 ◽  
Author(s):  
T. A. Waite ◽  
K. L. Field
Keyword(s):  
Gray Jays ◽  
Perisoreus Canadensis

scholarly journals Contamination of food with cadmium and dioxins – influence on the human body

2019 ◽  
Vol 65 (3) ◽  
Author(s):  
Aleksandra Słojewska ◽  
Izabela Gutowska
Keyword(s):  
General Population ◽  
Health Effects ◽  
Human Body ◽  
Bone Mineralization ◽  
The Body ◽  
Food Sources ◽  
Hormonal Balance ◽  
Small Doses ◽  
Contaminated Food

Introduction: Food is a carrier of many pollutants nowadays. For cadmium and dioxins, it is the main source of these compounds in the general population. Hence, the aim of this work was to collect data on the health effects associated with exposure to cadmium and dioxins which get into the human body through food.Materials and methods: A literature review was conducted by searching the scientific Medline database (PubMed) and Google Scholar.Results: Health effects associated with a long-term exposure to low doses of cadmium and dioxins may be nonspecific and are rarely attributed to food sources. These may cause disorders affecting hormonal balance, kidney function, lipid metabolism, fertility, cognitive function, bone mineralization, and susceptibility to diseases and allergies. These compounds may also lead to cancer development.Conclusions: The general population faces the problem of longterm exposure to small doses of these substances due to their accumulation in the body, even if their amounts do not exceed the relevant standards. The health effects of this type of exposure may be significantly delayed and are not likely to be attributed to the consumption of contaminated food. Consumers wishing to reduce the amounts of these compounds delivered to the body should limit the consumption of grilled and smoked products, and should also opt for organic food.

scholarly journals The Life and Death of the Supermarket:  How Food Trade Infrastructure Affects the  Design of Architectural and Urban Settings

2021 ◽  
Author(s):  
◽  
Mathew Lee
Keyword(s):  
Food Supply ◽  
Motor Vehicle ◽  
Research Question ◽  
Food Culture ◽  
Food Sources ◽  
Analysis Model ◽  
Departure Point ◽  
Positive Effects ◽  
Urban Market ◽  
The City

<p>Historically food has played an important role in how cities are shaped. The modern city is no exception to this, yet it holds an abstracted relationship to the hinterlands that feed it (Steel: 2008), thus giving the perception (particularly in Western cities) that constant food supply to the city is a given right. The problem of feeding cities still remains a challenge (Diamond: 2005), one that, in combination with an ever increasing scarcity of fossil fuels, has led to a emerging tide of urbanism looking to bring localised food back to prominence in the city. More so, investigating building infrastructure to mass produce food in cities themselves: the return to a city state model. A consequence of this is also a move towards a more resource sustainable city framework. However, there is little discussion around how this new food urbanism will be structured within the city, and conversely, how it will structure the city. The most prominent architectural/urban typology which represents food in the city currently is that of the supermarket building, a type which has evolved from the urban market but has shed its civic role (Steel: 2008). This is further characterised by the common use of the private motor vehicle to access the supermarkets site. What if we were to amputate the car from the supermarket? Would we return to the urban market as the defining food space typology in the city? Or would food space be embodied in a new formal language? Primary Research Question(s): How can we track the implications of food (supply, demand, requirements) for the contemporary Western city through a supermarket typology? Secondary Research Questions: How does food culture and its resulting space enhance the urban public sphere (i.e. the vitality of the city)? Methodology Using the analysis model of design (institutionalised/autonomous design process) versus nondesign (overlapping of cultural systems in which design is one of these) laid out by Diana Agrest in 1974 as an analysis departure point; the research will investigate the historical and contemporary role of food markets in cities. The supermarket typology will form the basis for how food exchange related design affects urban fabric build-up in Western cities. Through links in the literature review, as well as empirically based evidence, I draw through extrapolations of how a food market driven city might conduct urban change. This may nurture a more direct relationship to its surrounding geography (e.g. the hinterland) and the food sources needed to feed it. Empirical analysis has been conducted on what might typify a vibrant and civically significant urban market to counteract the research into supermarket typologies. The Queen Victoria Market in Melbourne, Australia, has been selected as this case study. There is an assumption that there are qualities instilled in urban markets which have more positive effects for urban environments than that of supermarkets. Thus, through looking at these environments it may be possible to tease out new directions for solidifying the prominence of food in the city once more.</p>

scholarly journals Brucellosis morbidity in Russia and Primorsky region

2022 ◽  
pp. 50-55
Author(s):  
G. T. Dzyuba ◽  
Y. E. Skurikhina ◽  
G. A. Zakharova ◽  
A. V. Ponomareva
Keyword(s):  
Average Rate ◽  
Federal District ◽  
Epidemiological Data ◽  
Morbidity Rate ◽  
Disease Rate ◽  
Occupational Groups ◽  
Current State ◽  
Far Eastern ◽  
Epidemiological Situation

Objective: Epidemiological data analysis concerning the spread of brucellosis in Russia and Primorsky Region, study of the manifestations of the epidemic process and the current state of brucellosis issue.Methods: Descriptive epidemiological analysis of materials on infectious morbidity based on state statistical reporting forms No. 1, No. 2 “Information on infectious and parasitic morbidity”.Results: Brucellosis affects workers in the main occupational groups of livestock breeders, workers involved in the processing of livestock, who contact sick animals and other sources of brucellosis infection. Primorsky Region is a territory with an unstable epidemiological situation on brucellosis. A different morbidity rates were registered over the years. However usually it does not exceed the national average rate. In 2009, the morbidity rate counted 27.5% less than in Russian Federation (0.21 and 0.29 per 100,000 respectively), compared to previous years, the average long-term morbidity rate in the region increased by 3.5 times. The disease rate for the period from 2009 to 2019 ranged from 0.05 to 0.21%. In 2012, it exceeded the index in the Far Eastern Federal District (0.1 per 100,000 population). Brucellosis cases were detected among livestock breeders during an extraordinary medical examination due to the bad situation on brucellosis among animals.Conclusions: In recent decades, the epizootic and epidemiological situation on brucellosis remains tense due to the decrease in the number of serological and bacteriological studies among animals and humans, the weakening of veterinary-sanitary control and the formation of new private farms.

Features of the Current Epidemic Process of Infectious Mononucleosis in the Nizhny Novgorod Region

2021 ◽  
pp. 79-86
Author(s):  
MI Popkova ◽  
OV Utkin
Keyword(s):  
Infectious Mononucleosis ◽  
Average Rate ◽  
Disease Incidence ◽  
Age Groups ◽  
Incidence Rates ◽  
Epidemiological Surveillance ◽  
Epidemic Process ◽  
Tract Infections ◽  
Nizhny Novgorod Region

Introduction: Today, we are witnessing the process of forming a fundamentally new epidemiological situation on infectious mononucleosis. Over the past decade, a general increase in the incidence of infectious mononucleosis, its proportion in the structure of respiratory tract infections, and economic importance was noted in Russia. Information about the epidemic process of infectious mononucleosis in different areas is limited. Our objective was to study the features of the epidemic process of infectious mononucleosis in the Nizhny Novgorod Region in 2010–2019. Methods: We conducted a retrospective epidemiological analysis of the incidence of infectious mononucleosis in the Nizhny Novgorod Region for 2010–2019 based on official statistics using standard statistical approaches. Results and discussion: The long-term incidence rate of infectious mononucleosis in the Nizhny Novgorod Region was stable (+0.6 %) with the long-term average rate of 12.6 ± 0.6 ‰оо. An autumn-winter-spring seasonality with two distinct peaks (in November–December and May) was revealed. The majority of cases were children aged 0–14 years (72.8 ± 2.2 %). The highest incidence rates were regis�tered in the age groups of 1–2 and 3-6 years. We established a reverse trend in the disease incidence among children aged 0–6 (decrease) and 7 years and older (increase). Adolescents aged 15–17 demonstrated the most pronounced growth rate (+7.5 %). The typical annual dynamics in adults was distinguished by a clear spring-summer seasonality, the absence of a characteristic growth in the autumn months, and a low rate in December. The identified features of the epidemic process in different age groups require clarification and detailing. Conclusions: We established recent patterns and features of the epidemic process of infectious mononucleosis in the Nizhny Novgorod Region. This work is an important component of epidemiological surveillance of infection and a scientific basis for improving the existing system of preventive and anti-epidemic measures.

scholarly journals Deeper waters are changing less consistently than surface waters in a global analysis of 102 lakes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rachel M. Pilla ◽  
Craig E. Williamson ◽  
Boris V. Adamovich ◽  
Rita Adrian ◽  
Orlane Anneville ◽  
...  
Keyword(s):  
Surface Water ◽  
Average Rate ◽  
Thermal Structure ◽  
Global Analysis ◽  
Regional Climate ◽  
Data Set ◽  
Water Column Stability ◽  
Temperature Trends ◽  
Lake Characteristics

AbstractGlobally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either surface water temperatures or thermal stability within lakes, and only 8.4% was explained by lake thermal region or local lake characteristics in a random forest analysis. These findings suggest that external drivers beyond our tested lake characteristics are important in explaining long-term trends in thermal structure, such as local to regional climate patterns or additional external anthropogenic influences.

THE FIRST 12 YEARS OF A LONG-TERM CROP ROTATION STUDY IN SOUTHWESTERN SASKATCHEWAN — NITRATE-N DISTRIBUTION IN SOIL AND N UPTAKE BY THE PLANT

1983 ◽  
Vol 63 (3) ◽  
pp. 563-578 ◽  
Author(s):  
D. W. L. READ ◽  
C. A. CAMPBELL ◽  
V. O. BIEDERBECK ◽  
G. E. WINKLEMAN
Keyword(s):  
Root Zone ◽  
Average Rate ◽  
N Uptake ◽  
Mineral N ◽  
N Application ◽  
Rooting Zone ◽  
Secale Cereale L ◽  
Rotation Study ◽  
Key Words Nitrate

The distribution of NO3-N in the soil, and N uptake by the crop during the first 12 yr of a long-term rotation study at Swift Current, Saskatchewan were studied. A considerable amount of NO3-N appeared to be leached beyond the rooting zone of the cereal crop in years of above average precipitation and also in some relatively dry years with heavy spring rains. Thus, leaching of NO3-N seemed to occur even under continuous wheat rotations. At all times there was considerable NO3-N situated at the 60- to 120-cm depth. In wet years N uptake by the plants reduced the amount of NO3-N located in the subsoil, but in dry years the amount of NO3-N in the subsoil remained higher throughout the growing season. The latter could result in groundwater pollution, especially if such a soil was fallowed the next year. Fall rye (Secale cereale L.) made more efficient use of mineral N than spring-sown crops. In dry years more NO3-N persisted in the root zone of N-fertilized wheat than in the root zone of unfertilized wheat, but in wet and average years there was little difference due to N application. The average rate of net NO3-N production in fallow land from spring thaw to freeze-up (166 days) was 107 kg∙ha−1. Values ranged from about 60 to 175 kg∙ha−1 with the lowest values being obtained during very dry or very wet years. The quantity of N mineralized (kg∙ha−1) between spring thaw and freeze-up was related to precipitation (mm) by the equation Nmin = 29.0 + 0.20 precipitation for the 0- to 60-cm depth (R2 = 0.65*). Key words: Nitrate leaching, N uptake, crop rotations, N mineralization rate

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