Flock formation in white pelicans

1982 ◽  
Vol 60 (5) ◽  
pp. 1024-1031 ◽  
Author(s):  
J. Brian E. O'Malley ◽  
Roger M. Evans
Keyword(s):  
Alternative Interpretation ◽  
Flock Size ◽  
Functional Information ◽  
Local Enhancement ◽  
Group Foraging ◽  
Gliding Flight ◽  
Effective Use

White pelicans travel between breeding colonies and distant foraging sites in flocks. We described the process of flock formation during departures from colonies at East Shoal Lake, Manitoba. Interdeparture intervals in 1978 and 1979 were significantly clumped, which suggests individual white pelicans follow one another when initiating foraging trips.Flocks increased in size and made increasing use of air thermals as they travelled toward foraging areas. Flocks were most common and most variable in size between 1145 and 1345. Flock size was stable over the season, while the number commuting each day increased geometrically to a maximum by the end of the nestling period.Flocks observed near the colonies were characterized by low, horizontal, flap-gliding flight. Further enroute they flew higher and showed greater frequencies of gliding and ascending flight associated with increasing use of thermals.Our results provide no support for the view that colonies and flocks represent manifestations of functional information centers. The results are in agreement with the alternative interpretation that colonies and flocks facilitate group foraging and permit effective use of local enhancement as a means of locating thermals.

Flock size and formation in black-billed gulls

1982 ◽  
Vol 60 (8) ◽  
pp. 1806-1811 ◽  
Author(s):  
Roger M. Evans
Keyword(s):  
Size Distribution ◽  
Causal Model ◽  
Causal Explanation ◽  
Flock Size ◽  
Group Foraging ◽  
Foraging Site ◽  
Site Tenacity

Black-billed gulls (Larus bulleri) depart form breeding colonies and foraging sites in nonrandom, clumped formations (flocks). Flocks leaving colonies were significantly smaller than those leaving foraging sites, in part owing to more "upflights" at foraging sites. When more birds left a colony per unit time, flocks were both larger and more frequent.A causal model was developed based on the assumptions that flock departures from a colony or foraging site result from the effects of social attractions superimposed on otherwise random departure intervals. This model successfully predicted the size distribution of flocks departing from four colonies and foraging sites. In conjunction with the concepts of site tenacity and habituation, the model also permits a causal explanation of differences in the size of flocks departing colonies compared with foraging sites, and of size differences in flocks arising from "upflights" as opposed to the more common "straggling" columnar formations. The model and results are consistent with the hypothesis that colonies function as assembly points that facilitate group foraging.

scholarly journals Patch Choice and Foraging Behavior of Nonbreeding American Flamingos in Yucatán, Mexico

The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 452-457 ◽  
Author(s):  
Felicity Arengo ◽  
Guy A. Baldassarre
Keyword(s):  
Flock Size ◽  
Ruppia Maritima ◽  
Patch Quality ◽  
Local Enhancement ◽  
Patch Choice ◽  
Plant Foods ◽  
Food Items ◽  
Phoenicopterus Ruber ◽  
Los Grupos ◽  
Potential Food

Abstract We studied nonbreeding American Flamingos (Phoenicopterus ruber ruber) using the Celestún Lagoon, Yucatán, Mexico, to characterize feeding patches and to describe factors influencing patch choice. Four invertebrate taxa (polychaetes, molluscs, chironomids, crustaceans) and two plant foods (seeds of widgeongrass [Ruppia maritima] and tubercles of muskgrass [Chara fibrosa]) comprised 99% of potential food items in 76 patches we sampled. Patches tended to be dominated either by invertebrates or plant foods; only 12% of patches had 50:50 ratios of plant and invertebrate foods. Food was more abundant in invertebrate versus plant-dominated patches (157 vs. 67 items patch−1), but flamingo flock size was smaller in invertebrate-dominated patches (60 vs. 147 birds patch−1). More individuals walk-fed as invertebrates increased in the patch, and more birds stamp-fed as plant foods increased. We argue that groups of foraging flamingos apparently indicate location of food for conspecifics (local enhancement), and may also provide information about patch quality through feeding behavior. Selección de Parches y Comportamiento de Forrajeo en Phoenicopterus ruber ruber en la Época No-Reproductiva en Yucatán, México Resumen. Estudiamos el comportamiento de forrajeo en un grupo de flamencos (Phoenicopterus ruber ruber) durante la época no-reproductiva en la Laguna de Celestún, Yucatán, México, para caracterizar a los parches de forrajeo y describir los factores que influyen en la selección del parche. Cuatro taxa de invertebrados (poliquetos, moluscos, quironómidos y crustáceos) y dos alimentos vegetales (semillas de Ruppia maritima y tubérculos de Chara fibrosa) conformaron el 99% de los elementos alimenticios potenciales para los flamencos en los 76 parches que muestreamos. Los parches tendieron a ser dominados por invertebrados o por alimento vegetal. Sólo el 8% de los parches tuvieron proporciones de 50:50% de invertebrados y alimentos vegetales. El alimento fue más abundante en parches dominados por invertebrados que en los dominados por alimentos vegetales (157 vs. 67 elementos por parche), pero el tamaño del grupo de flamencos fue más pequeño en parches dominados por invertebrados (60 vs. 147 individuos). La cantidad de individuos que se alimentaban caminando aumentó a medida que aumentaban los invertebrados en el parche, y la cantidad de individuos que se alimentaban parados aumentó a medida que aumentaban los alimentos vegetales. Sugerimos que los grupos de flamencos que forrajean aparentemente no sólo indican a los coespecíficos la ubicación del alimento (mejoramiento local), sino que también podrían proveen información sobre la calidad del parche a través del comportamiento de alimentación.

Flock Size and Behaviour in Captive Red-Billed Weaverbirds (Quelea Quelea): Implications for Social Facilitation and the Functions of Flocking

Behaviour ◽  
1979 ◽  
Vol 71 (1-2) ◽  
pp. 127-144 ◽  
Author(s):  
John Lazarus
Keyword(s):  
Social Facilitation ◽  
Feeding Behaviour ◽  
Alternative Interpretation ◽  
Flock Size ◽  
Weak Effect ◽  
Head Turning ◽  
The Social ◽  
Feeding Habitat ◽  
Normal Feeding ◽  
Escape Responses

AbstractAs a consequence of the anti-predator functions of flocking it is predicted that as flock size increases individual birds will (i) spend less time vigilant for predators and more time feeding, and (2) show fewer escape responses. These predictions are corroborated here in experiments with captive flocks of the red-billed weaverbird Quelea quelea varying in size from I to 32 individuals. In Experiment i the presence of companions reduced feeding latency and increased the rate of pecking. Feeding behaviour by the companion(s) was not necessary to produce these effects and did not produce additional facilitation of the rate of pecking, but feeding companions were more potent facilitators of the onset of pecking than non-feeding companions. The number of companions influenced different measures of feeding in different ways but facilitation reached a ceiling with three companions. These and other findings in the social facilitation literature are interpreted in the light of various propositions concerning the functions of flocking behaviour. In Experiment 2 undisturbed birds with companions made less frequent head-turns (possibly vigilant responses), wing-flicks (flight intention movements), hops and flights than birds on their own but the number of companions had no effect on the frequency of these responses. All responses correlated significantly and positively across individuals. Solitary individuals were more often perched, and less often on the ground, than those in flocks, a finding compatible with greater safety in flocks in the normal feeding habitat of the species. These (undisturbed) birds, in flocks of 1, 2 and 4, had lower rates of head-turning than those in another experiment (LAZARUS, 1979), which had been subjected to 10 alarm stimuli; in larger flocks there was no difference in the rate of head-turning. An alternative interpretation of the experimental results is evaluated and a possible reason for the weak effect of flock size considered.

Where and When To Feed: Sex and Experience Affect Access To Food in Wintering Snow Buntings

Behaviour ◽  
1997 ◽  
Vol 134 (1-2) ◽  
pp. 143-160 ◽  
Author(s):  
Richard D. Smith ◽  
Neil B. Metcalfe
Keyword(s):  
Flock Size ◽  
Foraging Success ◽  
Group Foraging ◽  
Feeding Station ◽  
Plectrophenax Nivalis ◽  
Access To Food ◽  
Winter Flocks ◽  
Differential Access

AbstractIn group-foraging species an individual's ability to feed in the most beneficial situations could influence its overall foraging success more than its ability to find and handle food. Here we examined whether sex, age or site experience of individual snow buntings Plectrophenax nivalis in winter flocks could help explain how frequently they were found in advantageous foraging situations. We found that inexperienced females were scarcer than expected in large flocks, that females fed less often in the early parts of flock feeding bouts, and that older and more experienced birds were more likely to feed in central flock positions. In addition, the likelihood of moving around the feeding station increased more with flock-size in females, while older birds were better at retaining access to the feeding patch. Previously reported differences in peck-rate between sex and age/experience categories of this species are therefore likely to be magnified by differential access to sources of food. We suggest that experience may help individuals to integrate within the feeding flock, but aggression from larger males may cause females to delay feeding or to feed in smaller flocks.

Wind Patterns affect Migration Flyways and Flock Size of a Soaring Bird over Sea

2016 ◽  
Vol 9 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Nicolantonio Agostini ◽  
Marco Gustin ◽  
Jost von Hardenberg ◽  
Michele Panuccio
Keyword(s):  
Large Data ◽  
Tyrrhenian Sea ◽  
Flock Size ◽  
Mediterranean Islands ◽  
Data Set ◽  
Gliding Flight ◽  
Water Surfaces ◽  
Straits Of Messina ◽  
Migration Pathways ◽  
Wind Patterns

Water surfaces are natural barriers for raptors mostly using soaring–gliding flight over land during migration. Among these, the European Honey Buzzard ( Pernis apivorus) is a total migrant, breeding in Europe and wintering in central western Africa. Each spring thousands of buzzards undertake long sea crossings between Tunisia and southern Italy, concentrating over small islands en route to central eastern Europe. The aim of this research is to investigate the influence of wind patterns on the flyways used by these raptors during this critical phase of migration through field observations at four small Mediterranean islands (Pantelleria, Marettimo, Ustica and Panarea) and at the Straits of Messina between 20 April and 20 May 2006–2013. In our analyses, peak days were considered for each site. This eight year multisite study allowed the collection of a large data set. While crossing the Channel of Sicily, migrants concentrated over Pantelleria (southern side of the Channel) during moderate NW winds, and over Marettimo (northern side) during weaker southerly winds. Over the island of Ustica (north-western Sicily, Tyrrhenian Sea) raptors were observed mostly with weak southerly winds. Over the island of Panarea (northeastern Sicily) and at the Straits of Messina, European Honey Buzzards passed with weak winds from W and NW, respectively. The average flock size during the peak days was significantly higher over the island of Pantelleria, where birds migrated during the stronger winds. The results of this study show that wind patterns affect both migration pathways and flocking behaviour of this species while crossing large water surfaces.

Analysis of 3-d molecular distribution with the digital imaging microscope

1988 ◽  
Vol 46 ◽  
pp. 40-41
Author(s):  
W.A. Carrington ◽  
F.S. Fay ◽  
K.E. Fogarty ◽  
L. Lifshitz
Keyword(s):  
Image Restoration ◽  
Digital Imaging ◽  
Fluorescent Dyes ◽  
Optical Axis ◽  
Computer Hardware ◽  
Computer Algorithms ◽  
Low Contrast ◽  
Specific Proteins ◽  
Effective Use ◽  
Single Living Cells

Advances in digital imaging microscopy and in the synthesis of fluorescent dyes allow the determination of 3D distribution of specific proteins, ions, GNA or DNA in single living cells. Effective use of this technology requires a combination of optical and computer hardware and software for image restoration, feature extraction and computer graphics.The digital imaging microscope consists of a conventional epifluorescence microscope with computer controlled focus, excitation and emission wavelength and duration of excitation. Images are recorded with a cooled (-80°C) CCD. 3D images are obtained as a series of optical sections at .25 - .5 μm intervals.A conventional microscope has substantial blurring along its optical axis. Out of focus contributions to a single optical section cause low contrast and flare; details are poorly resolved along the optical axis. We have developed new computer algorithms for reversing these distortions. These image restoration techniques and scanning confocal microscopes yield significantly better images; the results from the two are comparable.

Functional information from magnetic resonance imaging

1995 ◽  
Vol 53 ◽  
pp. 84-85
Author(s):  
Alan P. Koretsky ◽  
Afonso Costa e Silva ◽  
Yi-Jen Lin
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Cancer Biology ◽  
Imaging Modality ◽  
Magnetic Resonance Images ◽  
Great Success ◽  
Functional Information ◽  
Resonance Imaging ◽  
High Resolution Mri

Magnetic resonance imaging (MRI) has become established as an important imaging modality for the clinical management of disease. This is primarily due to the great tissue contrast inherent in magnetic resonance images of normal and diseased organs. Due to the wide availability of high field magnets and the ability to generate large and rapidly switched magnetic field gradients there is growing interest in applying high resolution MRI to obtain microscopic information. This symposium on MRI microscopy highlights new developments that are leading to increased resolution. The application of high resolution MRI to significant problems in developmental biology and cancer biology will illustrate the potential of these techniques.In combination with a growing interest in obtaining high resolution MRI there is also a growing interest in obtaining functional information from MRI. The great success of MRI in clinical applications is due to the inherent contrast obtained from different tissues leading to anatomical information.

Leadership in Teaching: Using Student Perspectives on Administration, Supervision and Private Practice

2011 ◽  
Vol 14 (1) ◽  
pp. 21-28
Author(s):  
Mary J. Emm ◽  
Christine P. Cecconi
Keyword(s):  
Student Perceptions ◽  
Clinical Supervision ◽  
Private Practice ◽  
Universal Design ◽  
Professional Preparation ◽  
Learning Activities ◽  
Functional Information ◽  
Course Content ◽  
Group Activities ◽  
Assessment Procedures

Clinical supervision is recognized as a distinctive area of practice and expertise, yet professional preparation in this area remains inadequate. This paper presents functional information describing the development and implementation of an experimental course on administration, supervision, and private practice, based on graduate student perceptions and preferences for course content and types of learning activities. Current pedagogical trends for universal design in learning and fostering student engagement were emphasized, including problem-based and collaborative learning. Results suggest that students were highly pleased with course content, interactive and group activities, as well as with assessment procedures used.

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