scholarly journals Cone distribution and visual resolution of the yellow‐legged gull, Larus michahellis (Naumann, 1840)

2021 ◽  
Author(s):  
Noemi Victory ◽  
Yolanda Segovia ◽  
Magdalena García
Keyword(s):  
Visual Resolution ◽  
Larus Michahellis

Yellow-legged Gull (Larus michahellis)

2020 ◽  
Author(s):  
Josep del Hoyo ◽  
Nigel Collar ◽  
Guy M. Kirwan ◽  
Chris Sharpe ◽  
Ernest Garcia
Keyword(s):  
Larus Michahellis

scholarly journals The relationship between visual resolution and cone spacing in the human fovea

2009 ◽  
Vol 13 (2) ◽  
pp. 156-157 ◽  
Author(s):  
Ethan A Rossi ◽  
Austin Roorda
Keyword(s):  
Visual Resolution ◽  
The Relationship

scholarly journals Yellow-legged Gull Larus michahellis captures and drowns a Feral Pigeon Columba livia

2016 ◽  
Vol 86 (1) ◽  
pp. 69 ◽  
Author(s):  
Alessandro Canestrelli ◽  
Fulvio Fraticelli
Keyword(s):  
Cognitive Ability ◽  
Columba Livia ◽  
Feral Pigeon ◽  
New Techniques ◽  
Small Lake ◽  
Innovative Methods ◽  
Larus Michahellis

A Yellow-legged Gull catching a Feral Pigeon, flies to a nearby small lake and kills him drowning. This behaviour can be explained or with higher cognitive ability, related with the use of innovative methods, or with a generalist behaviour that offers the opportunity to use new techniques.

DIFFRACTION AND VISUAL RESOLUTION

2009 ◽  
Vol 51 (2) ◽  
pp. 226-234
Author(s):  
ULF HALLDÉN
Keyword(s):  
Visual Resolution

The yellow-legged gull as a predator of lizards in Balearic Islands

2014 ◽  
Vol 35 (2) ◽  
pp. 207-213 ◽  
Author(s):  
Valentín Pérez-Mellado ◽  
Mario Garrido ◽  
Zaida Ortega ◽  
Ana Pérez-Cembranos ◽  
Abraham Mencía
Keyword(s):  
Balearic Islands ◽  
Predation Pressure ◽  
Vertebrate Species ◽  
Sources Of Information ◽  
Mediterranean Islands ◽  
Lizard Species ◽  
Podarcis Lilfordi ◽  
Larus Michahellis ◽  
Plasticine Models ◽  
Different Sources

Lizards and gulls cohabit in several Mediterranean islands. The yellow-legged gull, Larus michahellis, was found to prey several vertebrate species. However, precise information about the interaction between gulls and other vertebrates, particularly with lizards is still scarce. The Balearic lizard, Podarcis lilfordi, shares several coastal islets with the yellow-legged gull. Using two different sources of information, we studied the interaction of both species in Colom Island (Menorca, Balearic Islands, Spain). We studied the diet of the yellow-legged gull and learnt that the Balearic lizard is not a common prey of the yellow-legged gull. On the other hand, we studied the potential predation pressure of gulls on lizards, using plasticine models of lizards. We did two different experiments from which we can conclude that yellow-legged gulls rarely attack lizards and, consequently, cannot be considered a major threat for this endemic lizard species, at least in the population under study. Finally, we obtained evidence that plasticine models can only be employed with caution to assess predation pressure of opportunistic scavengers, much as gulls are. The majority of marks on models were not the consequence of true attacks by gulls, but the result of ground exploratory behaviour of gulls in search of any edible matter. Therefore, contrary to popular belief, in the case of the yellow-legged gull, the proportion of marked models would be an indication of ground-based wandering activity, rather than a result of its predation pressure on lizards.

scholarly journals Size-related Change in the Visual Resolution of Sunfish (Lepomis spp.)

1994 ◽  
Vol 51 (9) ◽  
pp. 2017-2026 ◽  
Author(s):  
William E. Walton ◽  
Stephen S. Easter Jr. ◽  
Celeste Malinoski ◽  
Nelson G. Hairston Jr.
Keyword(s):  
Body Size ◽  
Standard Length ◽  
Resolving Power ◽  
Pelagic Zone ◽  
Volume Increase ◽  
Fish Size ◽  
Visual Resolution ◽  
Search Volume ◽  
The Mean

Visual resolution of juvenile sunfish (Lepomis spp.) (8–33 mm standard length (SL)), although extremely poor in comparison with the larger individuals (38–160 mm SL) used in previous studies, improves rapidly as they grow. Histologically and behaviorally determined (mean reaction angle) visual angles of fish between 10 and 33 mm SL decrease by approximately 50 and 100 minutes of arc, respectively, and decline non-linearly with increasing fish size. Behaviorally determined visual resolution of juvenile sunfish based on maximum location distance (MLD) is equivalent to that calculated from intercone spacing. The mean reaction angle used in previous studies may have underestimated behavioral visual resolution of larger (> 38 mm SL) sunfish by approximately 30%. Visual volume and search volume increase by nearly three orders of magnitude in sunfish between 8 and 50 mm SL. After sunfish exceed 50 mm SL (when they can safely return to the pelagic zone), visual resolution increases comparatively slowly as body size increases. Our results suggest that the size-related change in behavioral visual resolution in sunfish is influenced by other factors in addition to the growth-related changes in the resolving power of the retina.

Diet of Yellow-legged Gull (Larus michahellis) chicks along the Spanish Western Mediterranean coast: the relevance of refuse dumps

2008 ◽  
Vol 150 (1) ◽  
pp. 265-272 ◽  
Author(s):  
Raül Ramos ◽  
Francisco Ramírez ◽  
Carolina Sanpera ◽  
Lluís Jover ◽  
Xavier Ruiz
Keyword(s):  
Western Mediterranean ◽  
Mediterranean Coast ◽  
Larus Michahellis ◽  
Refuse Dumps
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