Line transect surveying of arboreal monkeys: problems of group size and spread in a highly fragmented landscape

2010 ◽  
Vol 72 (12) ◽  
pp. 1100-1107 ◽  
Author(s):  
Stephen F. Ferrari ◽  
Renata R.D. Chagas ◽  
João Pedro Souza-Alves
Keyword(s):  
Group Size ◽  
Line Transect ◽  
Fragmented Landscape

scholarly journals Population parameters of the endangered titi monkey, Callicebus coimbrai Kobayashi and Langguth, 1999, in the fragmented landscape of southern Sergipe, Brazil

2011 ◽  
Vol 71 (3) ◽  
pp. 569-575 ◽  
Author(s):  
RRD. Chagas ◽  
SF. Ferrari
Keyword(s):  
Atlantic Forest ◽  
Considerable Proportion ◽  
Reliable Estimate ◽  
Line Transect ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Population Parameters ◽  
Data Set ◽  
In The Wild ◽  
A Site

The recently-discovered titi, Callicebus coimbrai, is endemic to the coastal Brazilian Atlantic Forest south of the São Francisco River, a region with a long tradition of deforestation. While a number of C. coimbrai populations have now been identified, little is known about basic population parameters. Considering the importance of this information for conservation planning, the population of a site in southern Sergipe (with a total area of forest of approximately 500 ha) was surveyed between April and October 2008. Standard line transect procedures were used in the four largest fragments, and additional monitoring included the use of playback broadcasts for the observation of titi groups. The presence of titis was confirmed in all the forest fragments at the site, including one of only five hectares. Two other primates - Callithrix jacchus and Cebus xanthosternos - were also recorded at the site, but were less abundant than titis. A total transect walk of 476 km provided 164 sightings of primates, the majority of which (104) were of Callicebus coimbrai. Titi groups ranged in size between two and five individuals. The most reliable estimate of overall population density, derived from the combined data set, was 12.6 individuals per km²;, although density was much higher in smaller (more disturbed) fragments. The total population of Callicebus coimbrai at the site was estimated to be at least 50 individuals, which may represent a considerable proportion of the population of the species remaining in the wild. In addition to its apparent tolerance of habitat fragmentation, densities of C. coimbrai recorded at the site compare favourably with those of other Atlantic Forest titi species.

The influence of habitat patch attributes on coyote group size and interaction in a fragmented landscape

2006 ◽  
Vol 84 (1) ◽  
pp. 80-87 ◽  
Author(s):  
Todd C Atwood
Keyword(s):  
Group Size ◽  
Spatial Interaction ◽  
Landscape Fragmentation ◽  
Forest Area ◽  
Fragmented Landscape ◽  
Habitat Patch ◽  
Model Group ◽  
Environmental Pressures ◽  
Resource Patches ◽  
Patch Attributes

From February 2000 to January 2002, I investigated correlates of landscape fragmentation with coyote (Canis latrans Say, 1823) group size and resulting effects on within-group spatial interaction in west-central Indiana, USA, to determine whether habitat patch dispersion and attributes mediated group maintenance and persistence. Twenty-one radio-collared coyotes were assigned to 15 social groups; group territories were then classified as having dispersed (n = 10) or aggregated (n = 5) resource patches. Group size was larger in territories with aggregated patches and was directly correlated to forest area and inversely correlated to corridor area (top-ranked model: group size = β0 + forest area – corridor area; AICc =  –2.12, ΔAICc = 0.0, ωi = 0.67). Territories with aggregated patches had proportionally more forest (mean = 0.41, SE = 0.02) and less corridor (mean = 0.01, SE = 0.002) habitats than territories with dispersed patches (forest area: mean = 0.11, SE = 0.01; corridor area: mean = 0.03, SE = 0.002). Within-group spatial interaction was not influenced by patch dispersion. I suggest that differences in territory and group sizes relative to patch dispersion reflect the complex combination of environmental pressures present in human-dominated landscapes and their potential to perturb canid social organization.

Adjusting for Group Size Influence in Line Transect Sampling

1990 ◽  
Vol 54 (3) ◽  
pp. 511 ◽  
Author(s):  
Thomas D. Drummer ◽  
Anthony R. Degange ◽  
Larry L. Pank ◽  
Lyman L. McDonald
Keyword(s):  
Group Size ◽  
Line Transect ◽  
Line Transect Sampling ◽  
Transect Sampling

Abundance estimate for a threatened population of franciscana dolphins in southern coastal Brazil: uncertainties and management implications

2010 ◽  
Vol 90 (8) ◽  
pp. 1649-1657 ◽  
Author(s):  
Daniel Danilewicz ◽  
Ignacio B. Moreno ◽  
Paulo H. Ott ◽  
Maurício Tavares ◽  
Alexandre F. Azevedo ◽  
...  
Keyword(s):  
Group Size ◽  
Rio Grande ◽  
Aerial Survey ◽  
Line Transect ◽  
Rio Grande Do Sul ◽  
Annual Increment ◽  
Western Atlantic ◽  
Availability Bias ◽  
Perception Bias ◽  
By Catch

The franciscana dolphin has been considered the most threatened small cetacean in the south-western Atlantic Ocean due to gillnet by-catch. The estimation of the species' abundance has been recommended as the highest research priority. A line transect aerial survey to estimate franciscana abundance in Rio Grande do Sul, southern Brazil, was carried out in February 2004. The overall surveyed area comprised 13,341 km2 and at least 20 transect lines. Abundance was estimated using distance sampling methods and assuming g(0) = 0.304. The corrected density is 0.51 franciscanas/km2, resulting in an abundance estimation of 6839 franciscanas (CV = 32%; 95% CI = 3709–12,594) for the surveyed area in Rio Grande do Sul. To improve this estimate: (a) perception bias should be determined; (b) the parameters influencing availability bias should be identified and quantified; and (c) survey sample size should be increased. While the lack of data to correct for perception bias and group size underestimation in this aerial survey is likely to yield an underestimate of franciscana abundance, the use of surfacing and diving time data from boat and land-based surveys to correct for availability bias is likely to cause its overestimation. Alternative values of the g0 group-size estimates and rates of increase were incorporated in the analyses, creating 240 different estimates of annual increment for this franciscana population. Even in the most optimistic scenario, the annual increment of franciscanas is not sustainable with the current levels of by-catch in Rio Grande do Sul, and fishery management to reduce by-catch must be initiated promptly.

scholarly journals Distribution of Western Hoolock Gibbons and Nutritional Status of Food Plants in Cachar District of Assam, India: Reaching Out to Local Communities for Conservation

2019 ◽  
Vol 67 (1) ◽  
pp. 25-39
Author(s):  
Mitrajit Deb ◽  
Shubhadeep Roychoudhury ◽  
Parimal C. Bhattacharjee ◽  
Indu Sharma ◽  
Sunil Nautiyal ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Group Size ◽  
Food Selection ◽  
Local Communities ◽  
Food Plants ◽  
Encounter Rate ◽  
Line Transect ◽  
Adult Males ◽  
Fuel Wood ◽  
Crude Fibre

Western hoolock gibbon (Hoolock hoolock) is listed as an endangered mammal in IUCN Red List. It is also listed in CITES Appendix I and in the Schedule I of the Indian Wildlife (Protection) Act, 1972. In the present work the status and distribution of Western hoolock gibbons in Cachar district of Assam, India was explored by conducting field studies from September 2012 to August 2013 using line transect and call count methods. Group composition, group size and adult sex ratio of nine gibbon groups and one solitary male were recorded. Groups comprised 36 % adult males, 32 % adult females, 10 % sub‑adult males, 11 % juveniles and 11 % infants and the encounter rate was 0.17. Group size ranged from 2 to 5 and mean group size was 2.8 ± 1.1. Nutritional status of food plants consumed by Western hoolock gibbons were analyzed and chemical composition was determined. Proximate analysis revealed that the mean value of crude protein (9.73 ± 0.4), crude fibre (16.1 ± 0.6), ether extract (1.07 ± 0.06), NFE (66.24 ± 0.43) and ash (7.03 ± 0.27) in plant samples. A moderate positive correlation was noted between higher protein content and higher crude fibre content in food plants (r = 0.48), which is likely to influence food selection and feeding pattern. Timber felling, fuel‑wood collection, agriculture and expansion of tea estates were identified as major threats to conservation of Western hoolock gibbons. The present study recommends taking up awareness programmes and formulation of policy interventions involving the local communities to arrive at a participatory biodiversity conservation plan at local levels particularly involving the village councils (gram panchayats).

An ecological basis for large group size in Colobus angolensis in the Nyungwe Forest, Rwanda

2001 ◽  
Vol 39 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Cheryl Fimbel ◽  
Amy Vedder ◽  
Ellen Dierenfeld ◽  
Felix Mulindahabi
Keyword(s):  
Group Size ◽  
Large Group ◽  
Colobus Angolensis ◽  
Ecological Basis

Bystanders, Group Size and the Informal Regulation of Violence

2008 ◽  
Author(s):  
Mark Levine ◽  
Rachel Best ◽  
Paul Taylor
Keyword(s):  
Group Size ◽  
Informal Regulation
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