85
behaviors like breach, pectoral slap, lobtail, are measured in frequency, number of
occurrence per unit of time, per example, the dolphin breached ten times per minute; behavioral states are behaviors of longer duration, like foraging, resting, are
measured in units of time, the length of time which the state lasts, per example, the
whale was resting for 25 min).
A list of well-defined behaviors, although challenging to develop, is essential.
Each behavior must be clearly and specifically described (Mann 2000) allowing that
different observers would interpret them the same way (Bart et al. 1998). Note that
the meaning or function of a behavior event cannot be part of the ethogram, because
the same behavior, the same movement, may occur in a variety of contexts and perhaps serve many different functions (Mann 2000). Better to use a very detailed
ethogram at the field while collecting data, and at the moment of the analyses, if
pertinent and/or necessary, cluster behaviors creating behavioral categories.
4.2.6 Land-Based Station Equipment
Another great advantage of land-based station studies is to be more cost-effective
than other methods. Basically, the needed equipment is the observational device:
binoculars, or spotting scope, and in studies where precise positioning is required,
theodolite or total station. Theodolite and total stations a priori are relatively expensive devices, however, if they have proper maintenance and cleaning, if their measurement systems are checked and balanced annually by a professional, they can
easily be used for decades, attenuating the initial investment. Also, as theodolite/
total station serves other purposes, they are often available for rent or to lend at
some academic departments (e.g., Geology, Geography, Cartography).
Besides the viewing device, depending on the objective of the study, some other
equipment’s shall be used, as a VHF radio for communication purposes (i.e. with
nearby vessels for example), a wind speedmeter used to monitor environmental
conditions, photographic camera, a voice recorder or even a video camera to film
animals. Some LBS studies use computers running dedicated software (described
later in this chapter), and even in places where there is no energy supply, solar panel
and batteries allow to overcome this limitation (Fig. 4.2).
4.2.7 Spotting Scope and Binoculars
A spotting scope is a small portable telescope with an erect image, optimized for the
observation on land. Observer use just one eye and it has to be mounted on a tripod
because of its magnification, usually ranging from 20× to 60×. Some have a zoom
eyepiece to give a range of magnifications. However, more than 60× can lead to
poorer image brightness, image shake and narrower field of view which difficult
finding and following animals in movement.
4 Land-Based Station Studies of Aquatic Mammals in Latin America: Understanding…
behaviors like breach, pectoral slap, lobtail, are measured in frequency, number of
occurrence per unit of time, per example, the dolphin breached ten times per minute; behavioral states are behaviors of longer duration, like foraging, resting, are
measured in units of time, the length of time which the state lasts, per example, the
whale was resting for 25 min).
A list of well-defined behaviors, although challenging to develop, is essential.
Each behavior must be clearly and specifically described (Mann 2000) allowing that
different observers would interpret them the same way (Bart et al. 1998). Note that
the meaning or function of a behavior event cannot be part of the ethogram, because
the same behavior, the same movement, may occur in a variety of contexts and perhaps serve many different functions (Mann 2000). Better to use a very detailed
ethogram at the field while collecting data, and at the moment of the analyses, if
pertinent and/or necessary, cluster behaviors creating behavioral categories.
4.2.6 Land-Based Station Equipment
Another great advantage of land-based station studies is to be more cost-effective
than other methods. Basically, the needed equipment is the observational device:
binoculars, or spotting scope, and in studies where precise positioning is required,
theodolite or total station. Theodolite and total stations a priori are relatively expensive devices, however, if they have proper maintenance and cleaning, if their measurement systems are checked and balanced annually by a professional, they can
easily be used for decades, attenuating the initial investment. Also, as theodolite/
total station serves other purposes, they are often available for rent or to lend at
some academic departments (e.g., Geology, Geography, Cartography).
Besides the viewing device, depending on the objective of the study, some other
equipment’s shall be used, as a VHF radio for communication purposes (i.e. with
nearby vessels for example), a wind speedmeter used to monitor environmental
conditions, photographic camera, a voice recorder or even a video camera to film
animals. Some LBS studies use computers running dedicated software (described
later in this chapter), and even in places where there is no energy supply, solar panel
and batteries allow to overcome this limitation (Fig. 4.2).
4.2.7 Spotting Scope and Binoculars
A spotting scope is a small portable telescope with an erect image, optimized for the
observation on land. Observer use just one eye and it has to be mounted on a tripod
because of its magnification, usually ranging from 20× to 60×. Some have a zoom
eyepiece to give a range of magnifications. However, more than 60× can lead to
poorer image brightness, image shake and narrower field of view which difficult
finding and following animals in movement.
4 Land-Based Station Studies of Aquatic Mammals in Latin America: Understanding…