430
2006), South Pacific Ocean islands (Helweg et al. 1998), Panama Gulf (Olviedo
et al. 2008), may result on differences in their acoustic signals.
As the oceanic dynamic between continental areas and islands is different, the
influence of environmental parameters in continental areas may be different and
provide the development of different acoustic signals that may be more efficient in
a certain environment.
Further studies should develop efforts in ecological comparisons between coastal
and oceanic areas which may be affecting male distribution and singing behavior in
a fine scale.
We registered an increase in behavioral activity according to the increase in the
group size and composition, with larger groups presenting a broader behavioral repertoire, in accordance with literature descriptions to other breeding areas (eg. Clapham
1996) and to the same breeding stock A, in the Abrolhos Bank (Morete et al. 2007),
which may contribute with the complex group structure during the breeding season
and may reflex in complexity of communicative skills (Freeberg et al. 2012).
The largest dive, of 13 min, was found for a singer male, very similar to the
results from a recent study in the Abrolhos Bank, which analyzed the same 4 group
categories and registered the largest time of 13,13 min, coming from a singer male
(Bezamat et al. 2010), indicating a probable general pattern for areas as distant as
500 km, in the same breeding stock.
Humpback whales sometimes show avoidance to boat approaching increasing
their dive patterns (Hoyt 2001). During many years researchers from both Abrolhos
Bank and North Coast of Bahia state, noted that the whales in North Coast are more
difficult to approach than in the core area of Abrolhos. The present data on the mean
percentage of time spend by diving whales was 85% in relation to the direct observation time. This value was more than double than previous studies from the
Abrolhos Bank, 42% in Peres (2006) and 30,1% in Benzamat et al. (2010).
The north coast do not present genetic differences from the Abrolhos Bank
(Cypriano-Souza et al. 2010) but is being considered as an area of more dynamic
movements of whales (Wedekin et al. 2010; Baracho-Neto et al. 2012), and this
could lead, in consequence, in more travelling behavior and even boat avoidance
through less time in the surface.
The narrow continental shelf in the North Coast also can play a role in the dive
patterns, making individuals travel more in a north-south direction to keep in shallow waters characteristic of their distribution, while in the Abrolhos Bank, the core
area in the Brazilian coast, more than double of density of whales (Andriolo et al.
2006, 2010; Wedekin et al. 2010).
As the whole breathing behavior of humpbacks do include those very short intervals, we decided to keep them all in the analyzes, different from Benzamat et al.
(2010) which only included intervals larger than 60 s, even considering that smaller
intervals prevailed, being 68% of their sampling.
Concluding, singer males are longer divers than other analyzed group structure,
presenting similar values, of 13 min, to the Abrolhos Bank, distant about 500 km
from our study area in the North Coast of Bahia state. Humpback whales in North
Coast spent about 85% of the direct observation in underwater activities, more than
M.R. Rossi-Santos
2006), South Pacific Ocean islands (Helweg et al. 1998), Panama Gulf (Olviedo
et al. 2008), may result on differences in their acoustic signals.
As the oceanic dynamic between continental areas and islands is different, the
influence of environmental parameters in continental areas may be different and
provide the development of different acoustic signals that may be more efficient in
a certain environment.
Further studies should develop efforts in ecological comparisons between coastal
and oceanic areas which may be affecting male distribution and singing behavior in
a fine scale.
We registered an increase in behavioral activity according to the increase in the
group size and composition, with larger groups presenting a broader behavioral repertoire, in accordance with literature descriptions to other breeding areas (eg. Clapham
1996) and to the same breeding stock A, in the Abrolhos Bank (Morete et al. 2007),
which may contribute with the complex group structure during the breeding season
and may reflex in complexity of communicative skills (Freeberg et al. 2012).
The largest dive, of 13 min, was found for a singer male, very similar to the
results from a recent study in the Abrolhos Bank, which analyzed the same 4 group
categories and registered the largest time of 13,13 min, coming from a singer male
(Bezamat et al. 2010), indicating a probable general pattern for areas as distant as
500 km, in the same breeding stock.
Humpback whales sometimes show avoidance to boat approaching increasing
their dive patterns (Hoyt 2001). During many years researchers from both Abrolhos
Bank and North Coast of Bahia state, noted that the whales in North Coast are more
difficult to approach than in the core area of Abrolhos. The present data on the mean
percentage of time spend by diving whales was 85% in relation to the direct observation time. This value was more than double than previous studies from the
Abrolhos Bank, 42% in Peres (2006) and 30,1% in Benzamat et al. (2010).
The north coast do not present genetic differences from the Abrolhos Bank
(Cypriano-Souza et al. 2010) but is being considered as an area of more dynamic
movements of whales (Wedekin et al. 2010; Baracho-Neto et al. 2012), and this
could lead, in consequence, in more travelling behavior and even boat avoidance
through less time in the surface.
The narrow continental shelf in the North Coast also can play a role in the dive
patterns, making individuals travel more in a north-south direction to keep in shallow waters characteristic of their distribution, while in the Abrolhos Bank, the core
area in the Brazilian coast, more than double of density of whales (Andriolo et al.
2006, 2010; Wedekin et al. 2010).
As the whole breathing behavior of humpbacks do include those very short intervals, we decided to keep them all in the analyzes, different from Benzamat et al.
(2010) which only included intervals larger than 60 s, even considering that smaller
intervals prevailed, being 68% of their sampling.
Concluding, singer males are longer divers than other analyzed group structure,
presenting similar values, of 13 min, to the Abrolhos Bank, distant about 500 km
from our study area in the North Coast of Bahia state. Humpback whales in North
Coast spent about 85% of the direct observation in underwater activities, more than
M.R. Rossi-Santos