Ki. Mccann et al., Techniques for determining movement patterns of Blue and Wattled Cranes inSouth Africa - colour-ringing versus satellite telemetry, OSTRICH, 2001, pp. 104-108
Knowledge about the annual movement patterns of endangered species is impor
tant in understanding various aspects of their biology, such as dispersal f
rom natal areas, seasonal movements,and areas where large numbers aggregate
. We compare two techniques of determining and analysing crane movement pat
terns in South Africa's threatened crane species, namely colour-ringing and
satellite telemetry. Wattled Crane and Blue Crane colour-ringing began in
1987 and 1993 respectively. This technique, although being labour-intensive
and time-consuming, has produced valuable information about Wattled Crane
movements in the eastern parts of the country, with resightings of 42% of t
he ringed Wattled Cranes. Since 1993,296 Blue Crane have been ringed but in
contrast to the Wattled Crane, the resightings have not added much to our
knowledge of this species' movement patterns. The Blue Crane, being endemic
to southern Africa and termed a local migrant, required a more sophisticat
ed technique for elucidating Blue Crane movements. Between 1996 and 1999, t
en Blue Cranes were fitted with satellite transmitters in four different pr
ovinces. The transmitters battery life lasted for an average of 333 days (r
ange: 182-707 days) giving an average of 118 fixes per transmitter life. Ho
wever, of these fixes an average of only 27 points per transmitter (22.9% o
f the points) were usable, i.e. had a sufficiently accurate rating and thus
provided the coordinates locating the bird to the nearest kilometre. There
fore, the selection of the appropriate technique for a movement study shoul
d dependent on the specific life history and behaviour of the particular sp
ecies, as both techniques have merits, depending on your needs and financia
l resources. Despite being time-consuming and labour-intensive, colour-ring
ing was by far the more accurate technique in identifying movement patterns
of the Wattled Crane, while satellite telemetry, although providing surpri
singly inaccurate data at a high expense (a serious consideration for Afric
an conservation work) is a consideration in species with long-distance move
ments. However, in a large population such as the Blue Crane in South Afric
a, and the short migratory distances this species undertakes it is more sui
table to utilise the colour ringing technique to track movement patterns.