scholarly journals Population size and status of the Yellow-breasted Racquet-tail Parrot Prioniturus flavicans

2000 ◽  
Vol 10 (2) ◽  
pp. 131-136 ◽  
Author(s):  
Jonathan S. Walker ◽  
Alexis J. Cahill
Keyword(s):  
Population Size ◽  
National Park ◽  
Nature Reserve ◽  
Population Estimates ◽  
Suitable Habitat ◽  
World Population ◽  
Restricted Range ◽  
The North ◽  
Density Values ◽  
Lowland Rainforest

Densities and population estimates are presented for the little known Yellow-breasted Racquet-tail Parrot Prioniturus flavicans, a species endemic to the Indonesian island of Sulawesi. Sixteen months of fieldwork was conducted within two protected areas in the island's northern peninsula. Densities were found to be much greater in the Bogani Nani Wartabone National Park than in the Tangkoko Duasaudara Nature Reserve: 16.27 and 7.18 birds/km2, respectively. The species has a much more restricted range than previously thought, being confined to the eastern two-thirds of the north peninsula. The remaining suitable habitat within this range, lowland rainforest, is estimated to be c. 11,300 km2. Using this figure in conjunction with density values we estimate that the world population for this species may be greater than 44,650 birds. Whilst such a population size is higher than previously thought, the very restricted distribution of the species causes concern for its future as loss and fragmentation of forest habitat are ongoing within its range.

Estimating brush-tailed rock-wallaby population size using individual animal recognition

2011 ◽  
Vol 33 (2) ◽  
pp. 228
Author(s):  
Karl Vernes ◽  
Stuart Green ◽  
Piers Thomas
Keyword(s):  
Population Size ◽  
National Park ◽  
New South ◽  
Morphological Characters ◽  
Population Estimates ◽  
Individual Animal ◽  
Mark Recapture ◽  
South Wales ◽  
North Eastern ◽  
Estimate Population Size

We undertook surveys of brush-tailed rock-wallabies (Petrogale penicillata) at four colonies in Oxley Wild Rivers National Park, north-eastern New South Wales, with the aim of developing a technique based upon individual animal recognition that could be used to obtain robust population estimates for rock-wallaby colonies. We identified individuals on the basis of distinct morphological characters in each colony using visual observations, and used the data within a ‘mark–recapture’ (or sight–resight) framework to estimate population size. More than 37 h of observations were made over 10 sampling days between 18 May and 9 June 2010. We could identify 91.7% of all rock-wallabies that were independently sighted (143 of 156 sightings of 35 animals). A small percentage of animals could not be identified during a visit because they were seen only fleetingly, were in dense cover, or were partly obscured by rock. The number of new animals sighted and photographed declined sharply at the midpoint of the survey, and there was a corresponding increase in resighting of known individuals. Population estimates using the mark–recapture methodology were nearly identical to estimates of total animals seen, suggesting that this method was successful in obtaining a complete census of rock-wallabies in each colony.

First systematic sampling approach to estimating the global population size of the Critically Endangered Blue-throated Macaw Ara glaucogularis

2020 ◽  
pp. 1-19 ◽  
Author(s):  
SEBASTIAN K. HERZOG ◽  
OSWALDO MAILLARD Z. ◽  
TJALLE BOORSMA ◽  
GUSTAVO SÁNCHEZ-ÁVILA ◽  
VÍCTOR HUGO GARCÍA-SOLÍZ ◽  
...  
Keyword(s):  
Population Size ◽  
Critically Endangered ◽  
Population Estimates ◽  
Suitable Habitat ◽  
Landsat 8 ◽  
Entire Area ◽  
Positive Effects ◽  
Population Size Estimates ◽  
Global Population ◽  
Sampling Approach

Summary Reliable population size estimates are imperative for effective conservation and management of globally threatened birds like the ‘Critically Endangered’ Blue-throated Macaw Ara glaucogularis. Endemic to one of South America’s largest grassland floodplains, the Llanos de Moxos in northern Bolivia, the species’ global population size is uncertain. The region’s inaccessibility renders the application of traditional methods for obtaining bird population estimates impracticable or cost prohibitive. We developed a simultaneous, multilocality, double-sampling approach combined with quantitative habitat availability analyses to obtain the first rigorous population size estimate for the Blue-throated Macaw. We established 11 survey areas across its three subpopulations that were visited twice by one team in each subpopulation over a 23-day period in the 2015 dry season and obtained additional count data from two roost sites. We classified suitable habitat (palm forest islands) using Landsat 8 images and CLASlite forest monitoring software. We extrapolated the number of macaws detected (conservative estimate of the total number of macaws [CETN], highest single count [HSC]) per 100 ha of suitable habitat in each survey area to the entire area of suitable habitat in all subpopulations combined, corrected for the species’ range occupancy of 34.3%. The total number of Blue-throated Macaws detected by survey (CETN) and roost site counts was 137. Across all survey areas, the number of macaws per 100 ha of suitable habitat was 4.7 for the first and 4.4 for the second period for CETN and 3.2 and 3.4, respectively, for HSC data. Corresponding global population estimates were 426–455 (CETN) and 312–329 (HSC) individuals. Other recent research and anecdotal data support these estimates. Although it would be premature to propose downlisting the species to ‘Endangered’, our findings indicate that it has a larger population and slightly larger range than previously thought, and that the positive effects of conservation actions are now becoming apparent.

scholarly journals Geographical analysis of six rare bird species in the Kruger National Park, South Africa

1996 ◽  
Vol 6 (2) ◽  
pp. 117-137 ◽  
Author(s):  
J. L. Hurford ◽  
A. T. Lombard ◽  
A. C. Kemp ◽  
G. A. Benn
Keyword(s):  
South Africa ◽  
National Park ◽  
Bird Species ◽  
Habitat Associations ◽  
Kruger National Park ◽  
Suitable Habitat ◽  
The North ◽  
North Eastern ◽  
Population Sizes ◽  
Data Book

SummaryTwenty-eight predominantly tropical bird species have ranges that only just extend into the north-eastern part of South Africa, mainly within the Kruger National Park (KNP). These species are listed as “rare” (200 breeding pairs) in the South African Red Data Book (Brooke 1984). This study assesses the extent to which six of these rare bird species represent viable populations in the KNP. Grid squares in the KNP (2.5 × 2.5 miles) were visually assessed according to several bird habitat parameters. Bird records were also plotted on this grid system and habitat associations were identified for each species. This allowed for the measurement of total suitable habitat within the KNP for each species. Bird densities within known habitat were determined using spot-mapping and fixed-distance strip-transect techniques. Estimated population sizes for each species were obtained by extrapolating density estimates to total suitable habitat. Of the six study species, Arnot's Chat, Rudd's Apalis, Wattle-eyed Flycatcher and Tropical Boubou are likely to occur in sufficient numbers to constitute viable populations within the KNP, with estimated population sizes of 1,394, 4/758/ 2,070 and 10,450 birds respectively. The populations of White-crowned Plover and Long-tailed Starling are probably too small to be viable in the long term, with estimated population sizes of 305 and 382 birds respectively. The results presented here are testable and can be used as a baseline for future monitoring.

scholarly journals Capitoline Dolphins: Residency Patterns and Abundance Estimate of Tursiops truncatus at the Tiber River Estuary (Mediterranean Sea)

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 275
Author(s):  
Daniela Silvia Pace ◽  
Chiara Di Marco ◽  
Giancarlo Giacomini ◽  
Sara Ferri ◽  
Margherita Silvestri ◽  
...  
Keyword(s):  
Population Size ◽  
Tursiops Truncatus ◽  
Site Fidelity ◽  
Bottlenose Dolphins ◽  
River Estuary ◽  
Suitable Habitat ◽  
Tyrrhenian Sea ◽  
Abundance Estimate ◽  
Photo Identification ◽  
Tiber River

Periodic assessments of population status and trends to detect natural influences and human effects on coastal dolphin are often limited by lack of baseline information. Here, we investigated for the first time the site-fidelity patterns and estimated the population size of bottlenose dolphins (Tursiops truncatus) at the Tiber River estuary (central Mediterranean, Tyrrhenian Sea, Rome, Italy) between 2017 and 2020. We used photo-identification data and site-fidelity metrics to study the tendency of dolphins to remain in, or return to, the study area, and capture–recapture models to estimate the population abundance. In all, 347 unique individuals were identified. The hierarchical cluster analysis highlighted 3 clusters, labeled resident (individuals encountered at least five times, in three different months, over three distinct years; n = 42), part-time (individuals encountered at least on two occasions in a month, in at least two different years; n = 73), and transient (individuals encountered on more than one occasion, in more than 1 month, none of them in more than 1 year; n = 232), each characterized by site-fidelity metrics. Open POPAN modeling estimated a population size of 529 individuals (95% CI: 456–614), showing that the Capitoline (Roman) coastal area and nearby regions surrounding the Tiber River estuary represent an important, suitable habitat for bottlenose dolphins, despite their proximity to one of the major urban centers in the world (the city of Rome). Given the high number of individuals in the area and the presence of resident individuals with strong site fidelity, we suggest that conservation plans should not be focused only close to the Tiber River mouths but extended to cover a broader scale of area.

scholarly journals Distribution, ecology and conservation of an endangered Andean hummingbird: the Violet-throated Metaltail (Metallura baroni)

2009 ◽  
Vol 19 (1) ◽  
pp. 63-76 ◽  
Author(s):  
BORIS A. TINOCO ◽  
PEDRO X. ASTUDILLO ◽  
STEVEN C. LATTA ◽  
CATHERINE H. GRAHAM
Keyword(s):  
Suitable Habitat ◽  
Species Occurrence ◽  
Entropy Model ◽  
Maxent Model ◽  
The North ◽  
The Andes ◽  
Guide Field ◽  
South Central ◽  
Detailed Assessment ◽  
Endangered Status

SummaryThe Violet-throated MetaltailMetallura baroniis a high altitude hummingbird endemic to south-central Ecuador currently considered globally ‘Endangered’. Here we present the first detailed assessment of its distribution, ecology and conservation. We first used a maximum entropy model (Maxent model) to create a predicted distribution for this species based on very limited species occurrence data. We used this model to guide field surveys for the species between April and October 2006. We found a positive relationship between model values and species presence, indicating that the model was a useful tool to predict species occurrence and guide exploration. In the sites where the metaltail was found we gathered data on its habitat requirements, food resources and behaviour. Our results indicate that Violet-throated Metaltail is restricted to the Western Cordillera of the Andes Mountains in Azuay and Cañar provinces of Ecuador, with an area of extent of less than 2,000 km2. Deep river canyons to the north and south, lack of suitable habitat, and potential interspecific competition in the east may limit the bird's distribution. The species occurred in three distinct habitats, includingPolylepiswoodland, the upper edge of the montane forest, and in shrubby paramo, but we found no difference in relative abundance among these habitats. The metaltail seems to tolerate moderate human intervention in its habitats as long as some native brushy cover is maintained. We found thatBrachyotumsp.,Berberissp., andBarnadesiasp. were important nectar resources. The ‘Endangered’ status of this species is supported due to its restricted distribution in fragmented habitats which are under increasing human pressures.

scholarly journals Estimating change in the geographical range and population size of Hinde's Babbler Turdoides hindei

2003 ◽  
Vol 13 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Philip Shaw ◽  
John Musina ◽  
Patrick Gichuki
Keyword(s):  
Protected Areas ◽  
Population Size ◽  
Geographical Range ◽  
Population Estimates ◽  
Extent Of Occurrence ◽  
Area Of Occupancy ◽  
Species Area ◽  
Gains And Losses ◽  
Global Population

Hinde's Babbler Turdoides hindei is a globally threatened Kenyan endemic, which during the 1990s, was known from just seven localities. Based mainly on surveys undertaken in 2000–2001, we estimate the species's global population size and compare recent changes in its “extent of occurrence” and “area of occupancy”. Historically, Hinde's Babbler has been recorded from c. 40 10 × 10 km squares; 27 pre-1980 and 19 subsequently, suggesting that its area of occupancy has declined by about 30%. In contrast, its extent of occurrence has declined by only 8%, this measure being less sensitive to the balance of gains and losses occurring near the centre of its range. During surveys in 1994 and 2000–2001, 157 groups were located, containing 665 birds, 75% of which were found at two intensively cultivated sites. Some 97% of birds were located in, or adjacent to, five Important Bird Areas, but only 8% were found within legally protected areas. Two extrapolated population estimates are presented, based on the number of birds likely to have been missed at survey sites, and the species' area of occupancy. These suggest that the global population of Hinde's Babbler is likely to fall within the range of 1,500–5,600 birds.

scholarly journals The influence of the 1991/92 drought on the woody vegetation of the Kruger National Park

Koedoe ◽  
1995 ◽  
Vol 38 (2) ◽  
Author(s):  
A.J. Viljoen
Keyword(s):  
National Park ◽  
Woody Species ◽  
Aerial Photographs ◽  
Woody Vegetation ◽  
General Area ◽  
Variable Intensity ◽  
The North ◽  
Olifants River ◽  
Area North ◽  
The Impact

All observations and data related to the impact of the 1991/92 drought on the woody vegetation, excluding the riverine vegetation of major rivers, are summarised. This includes data from a visual estimate of damage from aerial photographs, surveys on selected sites, and general observations. Despite lower rainfall, the area north of the Olifants River (excluding the far-northern part) was less affected than the area south of it, suggesting that the woody vegetation in the north is more adapted to drought. A characteristic of the drought was the localised distribution pattern and variable intensity of damage to the same species in the same general area. Information on 31 species are presented briefly. Although a large number of woody species was to some extent damaged, when the woody vegetation is considered as a whole, the influence of the drought was not very severe.

scholarly journals A first survey of the global population size and distribution of the Scottish Crossbill Loxia scotica

2010 ◽  
Vol 21 (2) ◽  
pp. 186-198 ◽  
Author(s):  
RON W. SUMMERS ◽  
STEPHEN T. BUCKLAND
Keyword(s):  
Population Size ◽  
Habitat Management ◽  
Disjunct Distribution ◽  
Population Estimates ◽  
Modal Number ◽  
Habitat Requirement ◽  
Bird Population ◽  
Different Seasons ◽  
Common Crossbill ◽  
Global Population

SummaryA survey of Scottish Crossbills Loxia scotica was carried out in 3,506 km2 of conifer woodland in northern Scotland during January to April 2008 to provide the first estimate of the global population size for this endemic bird. Population estimates were also made for Common Crossbills L. curvirostra and Parrot Crossbills L. pytyopsittacus within this range. Crossbills were lured to systematically selected survey points for counting, sexing and recording their calls for later call-type (species) identification from sonograms. Crossbills were located at 451 of the 852 survey points, and adequate tape-recordings made at 387 of these. The Scottish Crossbill had a disjunct distribution, occurring largely within the eastern part of the study area, but also in the northwest. Common Crossbills had a mainly westerly distribution. The population size of post-juvenile Scottish Crossbills was estimated as 13,600 (95% C.I. 8,130–22,700), which will approximate to 6,800 (4,065–11,350) pairs. Common Crossbills were more abundant within this range (27,100, 95% C.I. 14,700–38,400) and Parrot Crossbills rare (about 100). The sex ratio was not significantly different from parity for Scottish Crossbills. The modal number at survey points was two but numbers were larger in January than later in the survey. The numbers and distribution of all crossbill species are likely to vary between years, depending upon the size of the cone crops of the different conifers: all were coning in 2008. Common Crossbill and Parrot Crossbill numbers will also be affected by irruptions from continental Europe. A monitoring scheme is required to detect any population trend, and further work on their habitat requirement (e.g. conifer selection at different seasons) is needed to inform habitat management of native and planted conifer forests to ensure a secure future for this endemic bird.

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