Name: Marlon Lima
Type: PhD thesis
Publication date: 22/02/2022
Advisor:
Name |
Role |
|---|---|
| Karen Barbara Strier | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Albert David Ditchfield | Internal Examiner * |
| Andressa Gatti | External Alternate * |
| Danielle de Oliveira Moreira | External Alternate * |
| Fabiano Rodrigues de Melo | External Examiner * |
| Karen Barbara Strier | Advisor * |
| Milton Cezar Ribeiro | External Examiner * |
| Sérgio Lucena Mendes | Internal Examiner * |
Summary: Studies carried out over almost 40 years in the
population of northern muriquis (Brachyteles hypoxanthus) in the
Private Natural Heritage Reserve Feliciano Miguel Abdala, in
Minas Gerais, Brazil, offer a great opportunity to assess the
variation in the movement patterns of animals that live in groups
and its relationship with ecological, social and behavioral
phenomena that vary in space-time. The muriquis groups pass some
changes in this period, from cohesive groups that became fluid,
formation of new groups, increase and decrease in population, or
the increase in the use strata of the forest, such as the ground
use. So, in the first chapter social groups of northern muriquis
have fluid grouping patterns, which results in subgroups that
vary in size and composition throughout the year. In this study,
we investigate whether group size adjustments can influence
spatial variables such as daily path lengths and the distances
between subgroups. These results show that daily path lengths
were positively correlated to subgroup size only in the rainy
months and only to the proportion of females, and suggests that
the daily path length are linked to the availability and/or need
of more resources for females. The greater distance between
subgroups in the dry months reduces competition that is results
from the lower availability of resources, and, not being
correlated to subgroup size and composition was unexpected from
the point of view of competition, which would lead to group
fission, however, this is consistent with the benefits of
maintaining proximity between subgroups during intergroup
encounters. Both results show the flexibility that the
fission-fusion dynamics may offer, and indicate the importance of
considering inter and intragroup relations. Another change
observed in space use occurred after the reduction of the
muriquis population by about 10%. Therefore, in the second
chapter we verify if variations over time in the demography of
primate populations can influence how available space is used. We
analyzed the space use by five groups, when the population had
reduced, and we compared the results from when the population was
bigger. During the period of this study, the five groups of
muriquis used 12% less than previously observed, with a 35.8%
reduction of its use outside the area of the reserve. The home
ranges of the groups ranged also between 2.7% to 32.5% smaller
than previously observed. The size of the core area was not
influenced by the reduction in the number of individuals,
remaining stable in largest group, but in the other groups there
was an increase. Home ranges and core areas overlaps among all
groups were small or did not occur, however the formation of a
new group with the fission generated a moderate overlap between
these groups even after a few years. Tracking long-term space use
patterns after demographic changes and demonstrate the ability of
groups to adapt to ecological changes, such as more available
space, greater availability of resources and less competition,
and can provide a better understanding of space use in other
populations as well as in other species. In the third chapter, to
represent the reality of the space use those most arboreal
animals occupy, it would be more appropriate if we characterize
it in 3 spatial dimensions (3D), WHERE the inclusion of the
vertical axis can improve the understanding of the spatial
ecology of various organisms. We investigated the
three-dimensional (3D) space use in a group of muriquis, which
are able to explore a variety of vertical substrates, such as
canopy layers, understory and even ground use. We found that the
percentage of time that the muriquis occupied the forest strata
varied from 3% on the ground (0 m) to 35% (strata between 5 and
10 m). When we included in our analysis the altitude of elevation
and the height of the forest strata WHERE the behavioral
activities take place, the annual volume of the 3D home range was
118 million cubic meters, and the volume of the 3D core area was
20 million cubic meters, there was no correlation between 3D home
range and 2D home range, which means that we are measuring
different types of space use. However, 3D core areas were
correlated with 2D core areas, which indicates that muriquis need
a minimum area for their activities. These results show the
importance of the vertical space in analysis of the space use of
species that live in limited areas and in high density, as they
show the importance of understanding the possible benefits of
accessing varied resources intensively in various strata, and the
energy costs to explore slopes and the disturbed forests compared
to a flat area forest and less used strata.
