Changes in habitat use patterns by bottlenose dolphins over a 10-year period render static management boundaries ineffective

2014 ◽  
Vol 25 (5) ◽  
pp. 701-711 ◽  
Author(s):  
Elizabeth F. Hartel ◽  
Rochelle Constantine ◽  
Leigh G. Torres
Behaviour ◽  
2013 ◽  
Vol 150 (6) ◽  
pp. 635-657 ◽  
Author(s):  
J.S. Lewis ◽  
D. Wartzok ◽  
M.R. Heithaus

In dynamic fission–fusion societies, following specific individuals consistently would not be expected in the absence of benefits to followers. Followers in groups may benefit if leaders have greater knowledge about habitats that are available for foraging and how to access these areas efficiently. A small residential population of bottlenose dolphins (Tursiops truncatus) in the Lower Florida Keys (LFK) demonstrates such specific individual leadership, but why others choose to follow is unknown. To determine whether consistent leaders demonstrated greater knowledge of resources and habitat we (1) compared habitat use patterns across areas that varied in prey abundance for groups led by consistent leaders and groups led by individuals that did not consistently lead, (2) compared directness of travel along with number of lead animal switches when traveling for these same two group types and (3) compared home range size and home range complexity between animals that consistently led and those that did not. Foraging groups led by consistent leaders were sighted more frequently over habitat with higher fish biomass, while those led by non-consistent leaders were sighted most often over habitat with lower fish biomass. Groups with consistent leaders had less frequent lead animal switches and took more direct paths when traveling than groups led by those that did not consistently lead. Home ranges of consistent leaders did not differ in size from other individuals, but were more complex. Our results indicate that followers in LFK dolphin groups could potentially benefit from those that consistently lead due to use of profitable habitat, ability to navigate efficiently and potentially the number of areas consistent leaders are familiar with.


10.5597/00215 ◽  
2017 ◽  
Vol 11 (1-2) ◽  
pp. 47-61 ◽  
Author(s):  
Paula Laporta ◽  
Cristiane C.A. Martins ◽  
Liliane Lodi ◽  
Camila Domit ◽  
Els Vermeulen ◽  
...  

The review compiles available information about the habitat use patterns of bottlenose dolphins within the SWAO, including temporal analysis of survey effort allocation, and spatial analysis indicating areas of resident or seasonally resident populations. 


2017 ◽  
Vol 23 (10) ◽  
pp. 4045-4057 ◽  
Author(s):  
Ross E. Boucek ◽  
Michael R. Heithaus ◽  
Rolando Santos ◽  
Philip Stevens ◽  
Jennifer S. Rehage

Author(s):  
Daniel Danilewicz ◽  
Eduardo R. Secchi ◽  
Paulo H. Ott ◽  
Ignacio B. Moreno ◽  
Manuela Bassoi ◽  
...  

The patterns of habitat use by the franciscana dolphins (Pontoporia blainvillei) along its distribution are poorly known. This study investigates the patterns of habitat use with respect to depth for 181 individuals of different age, size, gender and reproductive condition off Rio Grande do Sul, southern Brazil. The results reveal that franciscanas are very homogeneously distributed according to depth. Individuals from all lengths utilize nearly the entire range of depths of the surveyed area. Larger or older animals do not use deeper waters than younger animals, indicating that body size and age are not limiting factors for franciscanas that occupy deeper or offshore waters. Gestation seems to not cause a change in the distribution of females. Although the sex-ratio of the overall data did not vary from 1:1 in different depth intervals, a small-scale comparison between the northern and southern coast demonstrated the existence of some kind of sexual segregation. Franciscana by-catch in Rio Grande do Sul is not sustainable and it is agreed that management procedures are needed. Nevertheless, the available data on species distribution do not allow the designing of a protected area in order to minimize the by-catches of a particular sex/reproductive class.


2017 ◽  
Vol 98 (5) ◽  
pp. 1109-1118
Author(s):  
Els Vermeulen

Very little information is available on bottlenose dolphin (Tursiops truncatus) habitat use in the South-western Atlantic. It is, however, essential in understanding their ecology and to improve conservation management. In this study, habitat use of bottlenose dolphins was examined in Bahía San Antonio, an area frequented by the species. Given the large tidal amplitude and extended intertidal zone in this bay, special focus was given to the intertidal vs subtidal habitat use patterns. Bottlenose dolphins were observed in only half of the surveyed area, with on average 1 dolphin group encountered per 100 km surveyed. All dolphin groups were seen in shallow waters <10 m deep. GLM analyses showed that especially during high tide, depth had an important effect on the dolphin encounter rate, with most dolphin groups encountered in the intertidal zone. While in the intertidal zone, most dolphin groups were observed to be engaged in surface feeding activities. The presented data indicate dolphins remained in shallow waters, and moved to the intertidal zone during high tide where they appear to find feeding opportunities. This information is believed to be of high value in understanding this population's ecological needs, and essential when aiming to improve marine conservation efforts at times of increased anthropogenic pressures in the area.


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