Group Foraging in Patchy Environments: The Importance of Coarse-Level Local Enhancement

1992 ◽  
Vol 23 (2) ◽  
pp. 159 ◽  
Author(s):  
Hannu Poysa
Keyword(s):  
Local Enhancement ◽  
Group Foraging ◽  
Patchy Environments ◽  
Coarse Level

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.

The effect of diffusion on giant pandas that live in complex patchy environments

2015 ◽  
Vol 20 (1) ◽  
pp. 56-71 ◽  
Author(s):  
Xiangyun Shi ◽  
◽  
Guohua Song ◽  
Zeyu Li ◽  
◽  
...  
Keyword(s):  
Giant Pandas ◽  
Patchy Environments

scholarly journals Global-Local Enhancement Network for NMF-Aware Sign Language Recognition

2021 ◽  
Vol 17 (3) ◽  
pp. 1-19
Author(s):  
Hezhen Hu ◽  
Wengang Zhou ◽  
Junfu Pu ◽  
Houqiang Li
Keyword(s):  
Sign Language ◽  
Daily Life ◽  
The Other ◽  
Challenging Problem ◽  
Language Recognition ◽  
Local Enhancement ◽  
Sign Language Recognition ◽  
Vocabulary Size ◽  
Hand Gestures ◽  
Fine Grained

Sign language recognition (SLR) is a challenging problem, involving complex manual features (i.e., hand gestures) and fine-grained non-manual features (NMFs) (i.e., facial expression, mouth shapes, etc .). Although manual features are dominant, non-manual features also play an important role in the expression of a sign word. Specifically, many sign words convey different meanings due to non-manual features, even though they share the same hand gestures. This ambiguity introduces great challenges in the recognition of sign words. To tackle the above issue, we propose a simple yet effective architecture called Global-Local Enhancement Network (GLE-Net), including two mutually promoted streams toward different crucial aspects of SLR. Of the two streams, one captures the global contextual relationship, while the other stream captures the discriminative fine-grained cues. Moreover, due to the lack of datasets explicitly focusing on this kind of feature, we introduce the first non-manual-feature-aware isolated Chinese sign language dataset (NMFs-CSL) with a total vocabulary size of 1,067 sign words in daily life. Extensive experiments on NMFs-CSL and SLR500 datasets demonstrate the effectiveness of our method.

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.

Sign in / Sign up

Export Citation Format

Share Document