scholarly journals Variation in Human Disturbance Differentially Affects Predation Risk Assessment in Western Gulls

The Condor ◽  
2005 ◽  
Vol 107 (1) ◽  
pp. 178-181 ◽  
Author(s):  
Nicolaas V. Webb ◽  
Daniel T. Blumstein
Keyword(s):  
Human Disturbance ◽  
Anthropogenic Impacts ◽  
Important Goal ◽  
Larus Occidentalis ◽  
Predation Risk Assessment ◽  
Santa Monica ◽  
Low Levels ◽  
A Site ◽  
Different Levels ◽  
Flight Initiation

Abstract Many studies have demonstrated that birds behave differently in areas with different levels of human disturbance. Studies frequently characterize sites as having an overall level of human disturbance, and compare how birds respond at sites with high and low levels of disturbance. Doing so assumes that disturbance has a fairly constant effect on animals throughout a site. We measured the distance at which individual Western Gulls (Larus occidentalis) moved away from an approaching observer along a stretch of beach on both sides of the Santa Monica Pier, a heavily visited tourist attraction in southern California. We found that these flight initiation distances decreased in areas where more people visited the beach, and specifically in a small area near the pier. We found that flight initiation distance changed very rapidly within a short distance from the pier. Our results indicate that anthropogenic features may leave a “behavioral footprint.” Identifying the scale of such behavioral footprints should be an important goal of studies that seek to reduce anthropogenic impacts on birds. La Variación del Disturbio Humano Afecta Diferencialmente la Percepción del Riesgo de Depredación en Gaviotas Larus occidentalis Resumen. Muchos estudios han demostrado que las aves se comportan de modo diferente en áreas con distintos niveles de disturbio humano. Los estudios frecuentemente caracterizan sitios con base en su nivel general de disturbio y comparan las respuestas de las aves entre lugares con niveles altos y bajos de disturbio. Al hacer esto, se supone que el disturbio tiene un efecto aproximadamente constante sobre los animales a través de un sitio dado. En este estudio medimos la distancia a la cual gaviotas de la especie Larus occidentalis se desplazaron alejándose de un observador a lo largo de un tramo de playa en ambos lados del embarcadero de Santa Monica, una atracción turística muy visitada ubicada en el sur de California. Encontramos que las distancias al observador a las que las aves iniciaron el vuelo disminuyeron en áreas donde más personas visitaron la playa, y específicamente en un área cercana al embarcadero. Las distancias a las que las gaviotas iniciaron el vuelo cambiaron muy rá pidamente en una distancia muy corta desde el puerto, hasta alcanzar una distancia constante. Nuestros resultados indican que las estructuras antropogénicas podrian dejar una “huella comportamental”. Identificar la escala de dichas huellas debería ser un objetivo importante de estudios que tengan como fin reducir el impacto antrópico sobre las aves.

scholarly journals Disturbances to the Ground and to the Stand in Beech Forests Due to Thinning Treatments Performed by Different Levels of Mechanization

2020 ◽  
Vol 3 (1) ◽  
pp. 58
Author(s):  
Rachele Venanzi ◽  
Loredana Barbona ◽  
Francesco Latterini ◽  
Rodolfo Picchio
Keyword(s):  
Soil Moisture ◽  
Forest Soil ◽  
Anthropogenic Impacts ◽  
Tree Canopy ◽  
Forest Operations ◽  
Beech Forests ◽  
High Soil Moisture ◽  
Forest Logging ◽  
Fagus Sylvatica L ◽  
Different Levels

The aim of this work was to assess the possible impacts on the forest soil and stand due to silvicultural treatment and forest operations in a beech high forest. Even aged beech forests (Fagus sylvatica L.) in the Municipality of Cappadocia (L’Aquila) and in the Municipality of Vallepietra (Roma) were analyzed. The analysis of the soil and stand were performed in order to assess the effects attributable to applied silviculture and forest logging. Two different logging methodologies (in particular for the extraction) were applied: mules were used in the areas with greater slopes and with obstacles, while for the areas with better accessibility, mechanical means were used, in this case tractors. In detail, the main objective was to assess the disturbance on the ground and on the stand, generated by the two different levels of mechanization. In addition, it was also interesting to understand the possible effect on the soil and specifically on the partial uncovering where part of the tree canopy was removed. Only through an accurate cross-analysis of the studied parameters and indices could the anthropogenic impacts on the soil and stand due to forest operations be highlighted according to the different logging methodologies applied. The main results showed that the disturbances caused to the soil and stand were essentially caused in the bunching and extraction operations. The importance of avoiding or limiting the continuous passage of vehicles and animals on forest soil clearly emerges, especially in conditions of high soil moisture. It is also important to use correct technologies that are adequate for the specific environmental characteristics and the work plan. Finally, it can be said that there was no difference in the disturbance caused by the two logging methods when compared. Substantial differences in terms of improvement can be defined when comparing the findings of this study with other research studies. This can be done by applying a different type of mechanization with a different logging system.

Time-Dependent Changes in Excitability After One-Trial Conditioning of Hermissenda

1997 ◽  
Vol 78 (6) ◽  
pp. 3460-3464 ◽  
Author(s):  
Terry Crow ◽  
Vilma Siddiqi
Keyword(s):  
Time Dependent ◽  
Control Group ◽  
Type B ◽  
Control Groups ◽  
Phototactic Behavior ◽  
Parallel Processes ◽  
Short And Long Term ◽  
A Site ◽  
Different Levels

Crow, Terry and Vilma Siddiqi. Time-dependent changes in excitability after one-trial conditioning of Hermissenda. J. Neurophysiol. 78: 3460–3464, 1997. The visual system of Hermissenda has been studied extensively as a site of cellular plasticity produced by classical conditioning. A one-trial conditioning procedure consisting of light paired with the application of serotonin (5-HT) to the exposed, but otherwise intact, nervous system produces suppression of phototactic behavior tested 24 h after conditioning. Short- and long-term enhancement (STE and LTE) of excitability in identified type B photoreceptors is a cellular correlate of one-trial conditioning. LTE can be expressed in the absence of STE suggesting that STE and LTE may be parallel processes. To examine the development of enhancement, we studied its time-dependent alterations after one-trial conditioning. Intracellular recordings from identified type B photoreceptors of independent groups collected at different times after conditioning revealed that enhanced excitability follows a biphasic pattern in its development. The analysis of spikes elicited by 2 and 30 s extrinsic current pulses at different levels of depolarization showed that enhancement reached a peak 3 h after conditioning. From its peak, excitability decreased toward baseline control levels 5–6 h after conditioning followed by an increase to a stable plateau at 16 to 24 h postconditioning. Excitability changes measured in cells from unpaired control groups showed maximal changes 1 h posttreatment that rapidly decremented within 2 h. The conditioned stimulus (CS) elicited significantly more spikes 24 h postconditioning for the conditioned group as compared with the unpaired control group. The analysis of the time-dependent development of enhancement may reveal the processes underlying different stages of memory for this associative experience.

scholarly journals Increasing corvid tolerance to humans in urban ecosystems with increasing latitude

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Nadezhda Poddubnaya ◽  
Tatyana Korotkova ◽  
Polina Vanicheva
Keyword(s):  
Environmental Factors ◽  
Human Disturbance ◽  
Urban Ecosystems ◽  
Flight Initiation Distance ◽  
Protection Measures ◽  
Non Invasive ◽  
Alert Distance ◽  
Behaviour Changes ◽  
Hooded Crows ◽  
Flight Initiation

The rapid growth of cities causes behaviour changes in birds in response to urban environmental factors. The avian response to human disturbance has recently been studied by a non-invasive research tool as an alert distance (AD) and a flight initiation distance (FID) assessment. The tolerance of hooded crows (n = 395), jackdaws (n = 394) and rooks (n = 169) to humans was assessed by AD and FID. It was shown that the FID of all species is maximal during the summer, when the parents send clear “danger—fly away” signals to the young and the birds fly away. The AD and FID of the three species reliably correlates with the season. Rooks showed FID species-specificity in seven cities of Eastern Europe. Comparison of the attitude of birds to people in cities that have similarities in human culture showed that tolerance increases with increasing latitude in all species and is statistically significant only in the jackdaw. This should be taken into account in environmental protection measures.

Changes in escape behaviour of black iguanas (Ctenosaura similis) over an anthropogenic disturbance gradient

Behaviour ◽  
2021 ◽  
pp. 1-21
Author(s):  
Pooja Panwar ◽  
Pilar Angélica Gómez-Ruiz ◽  
Matthew N. Zipple ◽  
Luis Sandoval
Keyword(s):  
Human Disturbance ◽  
Protected Area ◽  
Anthropogenic Disturbance ◽  
Escape Behaviour ◽  
Human Presence ◽  
Disturbed Areas ◽  
Disturbance Gradient ◽  
The Impact ◽  
Ctenosaura Similis ◽  
Flight Initiation

Abstract Studies on the impact of human activity on animal behaviour are critical for understanding the extent to which humans affect ecological dynamics. Previous studies have found that human presence alters antipredator behaviours, which can be measured by flight initiation distance (FID). We investigated escape behaviour of 96 black iguanas (Ctenosaura similis) across a gradient of human disturbance in six sites inside a protected area in Costa Rica. We used a field experiment to test for effect of human disturbance on FID. We found that individuals from higher disturbance sites had shorter FIDs, meaning that black iguanas from disturbed areas allow closer approaches. This finding is consistent with the prediction that some animals become more habituated to human presence as the degree of human disturbance increases. We propose that black iguanas’ ability to alter their behaviour in response to humans’ presence could make them especially adept at invading new environments.

Technosocial Space

2010 ◽  
pp. 54-69 ◽  
Author(s):  
Anne Sofie Laegran
Keyword(s):  
Rural Communities ◽  
Theory And Practice ◽  
Space And Place ◽  
The Internet ◽  
Place And Space ◽  
Identity Markers ◽  
A Site ◽  
Different Levels ◽  
The Way ◽  
Internet Cafes

The chapter is based on a study of Internet cafés in Norway, and interrogates the way space and place is produced in interconnections between people and technology in the Internet café. Drawing on actornetwork theory and practice-oriented theories of place and space, the Internet café is understood as technosocial spaces producing connections between people and places at different levels. Firstly, the Internet café can be understood as a hybrid, a site where users and technologies as well as space are coconstructed in entwined processes where gender, as well as other identity markers, are central in the way the technology, as well as the cafés, develop and are understood. The next level looks at the production of Internet cafés as technosocial spaces. Despite being perceived as an “urban” and “global” phenomenon, Internet cafés are configured based on local circumstances, in urban as well as rural communities. Differing images of what the cafés want to achieve, as well as material constrains, are at play in this process. Finally, the chapter shows how Internet cafés are places of connections, producing space beyond the walls of the café, linking the local into a translocal sphere.

scholarly journals Observations on microthermal fluctuations

1963 ◽  
Vol 19 ◽  
pp. 126-131
Author(s):  
C. R. Lynds
Keyword(s):  
Thermal Structure ◽  
Image Motion ◽  
Visual Images ◽  
Image Size ◽  
Large Telescope ◽  
Small Aperture ◽  
Large Aperture ◽  
Low Levels ◽  
A Site

The concern has been expressed many times by Dr. Bowen and others that a significant portion of the seeing deterioration may occur in levels of the atmosphere very near the ground, within a few tenths of meters of the ground. When I refer to the quality of seeing I am refering to the image size one observes in a telescope of very large aperture and I will assume that this is equivalent to image motion as observed in telescopes of very small aperture. I will not attempt a further justification for this concern; however this is the basis for the studies we are just beginning at Kitt Peak, where we will attempt to quantitatively show whether or not there is need for concern about the very low levels of the atmosphere. So we begin with the thesis that much of the poor seeing observed at a site, the enlargement of photographic or visual images as observed through a large telescope, is due to refractive inhomogeneities in the lower levels of the atmosphere, within less than 100 m above the telescope. We presume that these inhomogeneities are of local origin and that their distribution and motion is determined primarily by site topography, wind direction and velocity. The few experiments we have made thus far at Kitt Peak have been designed to ascertain quantitatively the importance of these factors. Our approach has been to make observations of the large-aperture seeing with simultaneous observations of the thermal structure of the air accessible to us immediately above the telescope.

scholarly journals Oak Regeneration in the Southern Appalachians: Potential, Problems, and Possible Solutions

1998 ◽  
Vol 22 (1) ◽  
pp. 11-18 ◽  
Author(s):  
James E. Cook ◽  
Terry L. Sharik ◽  
David Wm. Smith
Keyword(s):  
Review Article ◽  
Oak Forests ◽  
Southern Appalachians ◽  
Limiting Factor ◽  
Oak Regeneration ◽  
Advance Regeneration ◽  
Southern Appalachian ◽  
Stump Sprouting ◽  
Low Levels ◽  
A Site

Abstract Despite the large volumes written about "oak regeneration problems" on mesic sites, very little has been presented on the extent of regional variation in oak regeneration. In this review article, we examine several important facets of oak regeneration for the Southern Appalachian region. We conclude that: (1) the amount of reproduction (seedlings and/or sprouts) is seldom a limiting factor because these oak forests have an average advance regeneration density of more than 9000/ha; (2) about 75% of all oak stems sprout after harvesting, which; (3) makes stump sprouts a major source of oak regeneration and a more important component than in the Midwest; (4) harvesting usually leads to an increase in the number of oak seedlings on a site (mean density for the first 3 yr equals 15,750/ha); (5) on sites of SI50 = 17-19m, oaks typically make up 25-40% of the canopy 2-3 decades after a harvest; (6) on sites of SI > 20m, clearcutting leads to very low levels (~10%) of oak representation in the subsequent forest, whereas a shelterwood harvest will result in 25-30% oak abundance; and (7) a harvest of an oak-dominated forest, without any other treatments, will lead to a 50-70% decline in oak. These results suggest that there is ample potential to regenerate current oak forests to oak, but new trials are needed with more species and on a greater range of sites. Increasing the size of the advance regeneration and maximizing stump sprouting are two ways to increase the amount of oak after harvest. However, regeneration cuts by themselves will not assure maintenance of the oak component; several treatments that have shown promise—midstory manipulation, fire, and weeding—are recommended for further study. South. J. Appl. For. 22(1):11-18.

scholarly journals Productive and Economic Viability of Raising Beef Cattle in the Savanna of the Brazilian State of Goiás

2018 ◽  
Vol 56 (3) ◽  
pp. 395-410 ◽  
Author(s):  
Elis Regina de Oliveira ◽  
Victor Rezende Moreira Couto
Keyword(s):  
Beef Cattle ◽  
Economic Viability ◽  
Economic Sustainability ◽  
Grazing System ◽  
Technical Specifications ◽  
Beef Cattle Production ◽  
Low Levels ◽  
Start Ups ◽  
Different Levels ◽  
Dry And Rainy Seasons

Abstract: The present study evaluates the economic viability of four different models of beef cattle production in the rio Vermelho hydrographic basin. The study focuses on the traditional extensive ranching system, which was compared to three intensive systems, one based on low levels of concentrated supplementation, a second with low levels of concentrated supplementation and confinement for fattening and an intensive grazing system, with supplementation during the dry and rainy seasons. The investments were estimated for the different levels of technical specifications of each system. The net present values and internal return rate were used for the assessment of the economic viability of the project, considering the minimum rate of attractiveness, equivalent to the inflation-adjusted savings interest rate (6.17%). The continuity of the sector was evaluated based on the gross and net margins, and profitability rates, where the system is already installed. All four systems had gross and net margins and profitability consistent with their economic sustainability over both the short and long terms. However, only two systems (reduced consumption of concentrated supplements and the intensive grazing system) were economically viable as start-ups.

scholarly journals TMJ Dysfunction and Systemic Correlation

2020 ◽  
Vol 5 (1) ◽  
pp. 20 ◽  
Author(s):  
Luca Fiorillo ◽  
Giuseppe Musumeci
Keyword(s):  
The Body ◽  
Mixed Dentition ◽  
Dental Occlusion ◽  
Sports Performance ◽  
Muscular System ◽  
Medical Field ◽  
Starting Point ◽  
A Site ◽  
The Relationship ◽  
Different Levels

In recent years it has been conclusively shown how the position of the mouth in relation to the body affects the way of walking and standing. In particular, occlusion, the relationship between skull and jaw, swallowing and convergence of the eyes are in neuro-muscular relationship with the control and maintenance system of posture, integrating at different levels. This manuscript aims to be a summary of all the oral, occlusal and articular dysfunctions of TMJ with systemic and postural–muscular repercussions. Recent articles found in the literature that are taken into consideration and briefly analyzed represent an important starting point for these correlations, which are still unclear in the medical field. Posturology, occlusal and oral influences on posture, spine and muscular system are still much debated today. In the literature, there are articles concerning sports performance and dental occlusion or even the postural characteristics of adolescents or children in deciduous and mixed dentition. The temporomandibular joint, as the only joint of the skull, could therefore represent a site to pay particular attention to, and in some cases an ATM dysfunction could be a clue for the diagnosis of systemic pathologies, or it could be the repercussion.

Baroreceptor control of the cutaneous active vasodilator system

1996 ◽  
Vol 81 (5) ◽  
pp. 2192-2198 ◽  
Author(s):  
C. G. Crandall ◽  
J. M. Johnson ◽  
W. A. Kosiba ◽  
D. L. Kellogg
Keyword(s):  
Lower Body Negative Pressure ◽  
Thermal Conditions ◽  
External Pressure ◽  
Vascular Conductance ◽  
Carotid Baroreceptor ◽  
Vasodilator Activity ◽  
Forearm Vascular Conductance ◽  
Low Levels ◽  
A Site ◽  
Cardiopulmonary Baroreceptors

Crandall, C. G., J. M. Johnson, W. A. Kosiba, and D. L. Kellogg, Jr. Baroreceptor control of the cutaneous active vasodilator system. J. Appl. Physiol.81(5): 2192–2198, 1996.—We sought to identify whether reductions in cutaneous active vasodilation during simulated orthostasis could be assigned solely to cardiopulmonary or to carotid baroreflexes by unloading cardiopulmonary baroreceptors with low levels of lower body negative pressure (LBNP) or unloading carotid baroreceptors with external pressure applied over the carotid sinus area [carotid pressure (CP)]. Skin blood flow was measured at a site at which adrenergic function was blocked via bretylium tosylate iontophoresis and at an unblocked site. During LBNP of −5 and −10 mmHg in hyperthermia, neither heart rate (HR) nor cutaneous vascular conductance (CVC) at either site changed ( P > 0.05 for both), whereas forearm vascular conductance (FVC) was reduced (−5 mmHg: from 21.6 ± 4.8 to 19.8 ± 4.1 FVC units, P = 0.05; −10 mmHg: from 22.3 ± 4.0 to 19.3 ± 3.7 FVC units, P = 0.002). LBNP of −30 mmHg in hyperthermia reduced CVC at both sites (untreated: from 51.9 ± 5.7 to 43.2 ± 5.1% maximum, P = 0.02; bretylium tosylate: from 60.9 ± 5.4 to 53.2 ± 4.4% maximum, P = 0.02), reduced FVC (from 23.2 ± 3.6 to 18.1 ± 3.3 FVC units; P = 0.002), and increased HR (from 83 ± 4 to 101 ± 3 beats/min; P = 0.003). Pulsatile CP (45 mmHg) did not affect FVC or CVC during normothermia or hyperthermia ( P > 0.05). However, HR and mean arterial pressure were elevated during CP in both thermal conditions (both P < 0.05). These results suggest that neither selective low levels of cardiopulmonary baroreceptor unloading nor selective carotid baroreceptor unloading can account for the inhibition of cutaneous active vasodilator activity seen with simulated orthostasis.

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