scholarly journals Experimenting usage of Camera-traps for Population Dynamics Study of the Asian Elephant Elephas Maximus in Southern India

2007 ◽  
Vol 6 (1) ◽  
pp. 81-95
Author(s):  
Surendra Varma ◽  
André Pittet ◽  
H. S. Jamadagni
Keyword(s):  
Population Dynamics ◽  
Cost Effective ◽  
Camera Trap ◽  
Camera Traps ◽  
Asian Elephant ◽  
Adult Males ◽  
Adult Females ◽  
Juvenile Males ◽  
Long Term Studies

To evaluate the application of camera-trap technology in population dynamics studies of the Asian elephant, indigenously designed, cost-effective, infrared-triggered camera-traps were used.Usability of pictures was defined based on quality, clarity and positioning of the subject.With 99 pictures of 330 elephants, 20 sequences were obtained and 44 distinct individuals were identified.It was found that 38.6% were adult females, 4.5% adult males, 13.6% sub-adult females, 6.8% sub-adult males, 20.4% juvenile females,while juvenile males were poorly represented(2%), and 13.6% were calves.These results were surprising identical with those of other systematic and long-term studies.

Time-Budgets of Camargue Horses Ii. Time-Budgets of Adult Horses and Weaned Sub-Adults

Behaviour ◽  
1980 ◽  
Vol 72 (1-2) ◽  
pp. 26-48 ◽  
Author(s):  
Patrick Duncan
Keyword(s):  
Social Structure ◽  
Social System ◽  
General Trend ◽  
Small Population ◽  
Time Budgets ◽  
Adult Males ◽  
Adult Females ◽  
Young Horses

AbstractTime-budgets of adult and weaned sub-adult horses were studied in a small population of Camargue horses living in semi-liberty. The categories of activities used were: Standing resting, Lying flat, Lying up, Standing alert, Walking, Trotting, Galloping, Rolling and Foraging. The main differences in time-budgets were related to age and to sex : young horses spent more time lying (sleeping), males spent more time standing alert and in rapid movements (trot, gallop), while usually foraging less than did the adult females. During the three years of the study the population increased from 20 to 54 horses and there were considerable changes in social structure as the number of adult males increased. Associated with these developments there were some changes between years in the time-budgets: the most striking of which was a general trend for all horses to spend less time lying. Nonetheless the time-budgets showed a considerable constancy across years and age/sex-classes, especially with regard to time spent foraging. This conclusion may provide a clue as to why horses have an unusual social system based on long term relationships between a male and the females of his harem.

scholarly journals Long-term monitoring of margays (Leopardus wiedii): Implications for understanding low detection rates

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247536
Author(s):  
Bart J. Harmsen ◽  
Nicola Saville ◽  
Rebecca J. Foster
Keyword(s):  
Detection Rate ◽  
Camera Trap ◽  
Wide Distribution ◽  
Camera Traps ◽  
Detection Rates ◽  
Terrestrial Mammals ◽  
Exclusive Territories ◽  
Carnivore Species ◽  
Density Population

Population assessments of wide-ranging, cryptic, terrestrial mammals rely on camera trap surveys. While camera trapping is a powerful method of detecting presence, it is difficult distinguishing rarity from low detection rate. The margay (Leopardus wiedii) is an example of a species considered rare based on its low detection rates across its range. Although margays have a wide distribution, detection rates with camera traps are universally low; consequently, the species is listed as Near Threatened. Our 12-year camera trap study of margays in protected broadleaf forest in Belize suggests that while margays have low detection rate, they do not seem to be rare, rather that they are difficult to detect with camera traps. We detected a maximum of 187 individuals, all with few or no recaptures over the years (mean = 2.0 captures/individual ± SD 2.1), with two-thirds of individuals detected only once. The few individuals that were recaptured across years exhibited long tenures up to 9 years and were at least 10 years old at their final detection. We detected multiple individuals of both sexes at the same locations during the same survey, suggesting overlapping ranges with non-exclusive territories, providing further evidence of a high-density population. By studying the sparse annual datasets across multiple years, we found evidence of an abundant margay population in the forest of the Cockscomb Basin, which might have been deemed low density and rare, if studied in the short term. We encourage more long-term camera trap studies to assess population status of semi-arboreal carnivore species that have hitherto been considered rare based on low detection rates.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole Microtus Montanus

2005 ◽  
Vol 29 ◽  
pp. 49-51
Author(s):  
Alita Pinter
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Population Density ◽  
Climatic Factors ◽  
Small Rodents ◽  
Microtus Montanus ◽  
Small Measure ◽  
Long Term Studies

A variety of hypotheses has been proposed to explain multiannual fluctuations in population density ("cycles") of small rodents (for reviews see Finerty 1980, Taitt and Krebs 1985). Doubtless, such cycles - known since antiquity (Elton 1942) - result from an interaction of a multitude of factors. However, the inability of extant hypotheses, alone or in combination, to explain the causality of cycles rests in no small measure with the fact that long-term studies of the phenomenon are notoriously uncommon.

Exposure of Spectacled Eiders and other diving ducks to lead in western Alaska

1997 ◽  
Vol 75 (3) ◽  
pp. 439-443 ◽  
Author(s):  
Paul L. Flint ◽  
Margaret R. Petersen ◽  
J. Barry Grand
Keyword(s):  
Blood Lead ◽  
Breeding Population ◽  
Atomic Absorption Spectrophotometry ◽  
Adult Males ◽  
Long Term Effects ◽  
Brood Rearing ◽  
Diving Ducks ◽  
Adult Females ◽  
Lead Levels

Lead poisoning, resulting from ingestion of spent shot, has been identified as a cause of mortality in Spectacled Eiders (Somateria fischeri) on the Yukon–Kuskokwim Delta, Alaska. We examined lead-exposure rates of adult and juvenile Spectacled Eiders and other diving ducks, using atomic absorption spectrophotometry of blood samples. Additionally, we X-rayed birds in the field to identify ingested shot. We detected shot in the gizzards of 11.6% of Spectacled Eiders X-rayed. During the period from arrival through incubation, 13.0% of adult females and 6.6% of adult males had elevated blood lead levels when captured. During the brood-rearing period, 35.8% of adult females and 12.2% of ducklings were exposed to lead when captured. There was an increase in the probability of exposure of adult females with date sampled. We predict that 50% of the successfully breeding hens were likely exposed to lead, and 25–37% of the Spectacled Eider breeding population was exposed to lead. The long-term effects of sublethal doses on Spectacled Eiders are unknown; however, exposure of nesting females and young birds to lead may result in reduced over-winter survival and (or) reduced fecundity.

scholarly journals FoxMask: a new automated tool for animal detection in camera trap images

2019 ◽  
Author(s):  
Eric Devost ◽  
Sandra Lai ◽  
Nicolas Casajus ◽  
Dominique Berteaux
Keyword(s):  
Moving Objects ◽  
Data Extraction ◽  
Cost Effective ◽  
Camera Trap ◽  
Biological Data ◽  
Camera Traps ◽  
Computer Assisted ◽  
List Type ◽  
Background Estimation ◽  
Animal Detection

SUMMARYCamera traps now represent a reliable, efficient and cost-effective technique to monitor wildlife and collect biological data in the field. However, efficiently extracting information from the massive amount of images generated is often extremely time-consuming and may now represent the most rate-limiting step in camera trap studies.To help overcome this challenge, we developed FoxMask, a new tool performing the automatic detection of animal presence in short sequences of camera trap images. FoxMask uses background estimation and foreground segmentation algorithms to detect the presence of moving objects (most likely, animals) on images.We analyzed a sample dataset from camera traps used to monitor activity on arctic fox Vulpes lagopus dens to test the parameter settings and the performance of the algorithm. The shape and color of arctic foxes, their background at snowmelt and during the summer growing season were highly variable, thus offering challenging testing conditions. We compared the automated animal detection performed by FoxMask to a manual review of the image series.The performance analysis indicated that the proportion of images correctly classified by FoxMask as containing an animal or not was very high (> 90%). FoxMask is thus highly efficient at reducing the workload by eliminating most false triggers (images without an animal). We provide parameter recommendations to facilitate usage and we present the cases where the algorithm performs less efficiently to stimulate further development.FoxMask is an easy-to-use tool freely available to ecologists performing camera trap data extraction. By minimizing analytical time, computer-assisted image analysis will allow collection of increased sample sizes and testing of new biological questions.

scholarly journals PRESENCE of SUMATRAN ELEPHANTS (Elephas maximus sumatranus) in THE ECOTONE AREA of SEMBILANG NATIONAL PARK (TNSTNS) and PALM OIL PLANTATION in SEMENANJUNG BANYUASIN SEMENANJUNG, SOUTH SUMATRA PROVINCE

2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Dafid Pirnanda ◽  
Indra Yustian ◽  
Zulkifli Dahlan ◽  
Winda Indrianti ◽  
Ina Aprilia ◽  
...  
Keyword(s):  
Palm Oil ◽  
National Park ◽  
Secondary Data ◽  
Camera Trap ◽  
Camera Traps ◽  
Elephas Maximus ◽  
Conservation Area ◽  
Young Females ◽  
Adult Females ◽  
Data Archives

A research to monitor the presence of Sumatran elephant between two ecosystem in Sembilang National Park (TNSTNS) and palm palm oilplantation has been conducted on March until June 2019 at Semenanjung Banyuasin Semenanjung, South Sumatra. This research aimed to verify the presence of Sumatran elephantpopulation and to estimate the number of elephant individuals in the area. The methods used weredirect observation during the day and indirect monitoring through installation of Camera Traps for 1 month. In addition, secondary data was collected in the form of data archives from the palm oil plantation records and interviews with affected plantation workers. From direct observation, Wedirect encountered one elephant individual and fifteen signs of elephant activities, such as sounds, footprints, and feces. From camera trap photos, we identified and verified onepopulation of Sumatran Elephants which consisted of at least twenty-two individuals with composition as follows: eight adult females, two young females, three infant females, and nine males. The ecotone area between TNS and palm palm oil plantation should be designated as a new habitat patchof Sumatran elephant that needs to be managed appropriately in order to maintain the designation of the area as a conservation area.

scholarly journals Quantifying whether different demographic models produce incongruent results on population dynamics of two long-term studied rodent species

2017 ◽  
Vol 3 (1) ◽  
pp. 18-26
Author(s):  
Giovanni Amori ◽  
Valentina De Silvestro ◽  
Paolo Ciucci ◽  
Luca Luiselli
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Population Size ◽  
Myodes Glareolus ◽  
Suitable Model ◽  
Demographic Model ◽  
Apodemus Flavicollis ◽  
Demographic Models ◽  
Long Term Studies

Abstract1. Population density (ind/ha) of long-term (>15 years) series of CMR populations, using distinct demographic models designed for both open and closed populations, were analysed for two sympatric species of rodents (Myodes glareolus and Apodemus flavicollis) from a mountain area in central Italy, in order to test the relative performance of various employed demographic models. In particular, the hypothesis that enumeration models systematically underestimate the population size of a given population was tested.2. Overall, we compared the performance of 7 distinct demographic models, including both closed and open models, for each study species. Although the two species revealed remarkable intrinsic differences in demography traits (for instance, a lower propensity for being recaptured in Apodemus flavicollis), the Robust Design appeared to be the best fitting model, showing that it is the most suitable model for long-term studies.3. Among the various analysed demographic models, Jolly-Seber returned the lower estimates of population density for both species. Thus, this demographic model could not be suggested for being applied for long-term studies of small mammal populations because it tends to remarkably underestimate the effective population size. Nonetheless, yearly estimates of population density by Jolly-Seber correlated positively with yearly estimates of population density by closed population models, thus showing that interannual trends in population dynamics were uncovered by both types of demographic models, although with different values in terms of true population size.

scholarly journals Microhabitat preferences of the freshwater prawn Macrobrachium jelskii (Decapoda: Palaemonidae)

2019 ◽  
Vol 109 ◽  
Author(s):  
Jersei N. Silva ◽  
Guilherme de Oliveira ◽  
Sérgio S. da Rocha
Keyword(s):  
Sex Ratio ◽  
Water Reservoir ◽  
Habitat Choice ◽  
Freshwater Prawn ◽  
Adult Males ◽  
Adult Females ◽  
Males And Females ◽  
Microhabitat Preferences ◽  
Lower Depth ◽  
Juvenile Males

ABSTRACT We analyzed the microhabitat preferences of Macrobrachium jelskii (Miers, 1877) males and females inhabiting an urban water reservoir in Cruz das Almas, Bahia, Brazil. Prawns were collected monthly, from March 2015 to February 2016, in three microhabitats, using a sieve. Each microhabitat was dominated by one macrophyte species: Eleocharis sp. (M1), Cabomba sp. (M2), and Nymphaea sp. (M3). The prawns were measured (carapace length), and categorized as juvenile males, adult males, juvenile females, non-ovigerous adult females and ovigerous adult females. An analysis of variance (ANOVA) was used to compare the number and size of individuals. The sex ratio and frequency of ovigerous females in the three microhabitats were also calculated. The sex ratio was biased towards females in M1 and did not deviate from 1:1 in M2 and M3. When prawns were separated into five categories we observed that non-ovigerous adult females were more abundant in M1, while adult males were the most abundant demographic category in M2 and M3. Juveniles of both sexes and ovigerous females showed no microhabitat preference, although M1 and M2 appeared to be more suitable for the latter. Adult females were the largest individuals in all microhabitats. Food availability, lower depth and lower predation pressure in M1 are the main factors that make M1 more suitable for M. jelskii, particularly non-ovigerous adult females and larger adult males. Intraspecific competition for shelter in M1 might also occur and adult females win this competition due to their larger body size. Therefore, adult males are found in higher abundance in M2 and M3 and the juvenile of both sexes spread evenly across all microhabitats. Our results help to understand the ecological role and the niche used by M. jelskii. Future studies on the habitat choice and predation under laboratory conditions should help to understand the behavior of this species.

Demography of a population of Peromyscus leucopus

1979 ◽  
Vol 57 (2) ◽  
pp. 323-328 ◽  
Author(s):  
Richard M. Harland ◽  
Peter J. Blancher ◽  
John S. Millar
Keyword(s):  
Peromyscus Leucopus ◽  
Adult Males ◽  
Adult Mice ◽  
Adult Females ◽  
Young Of The Year ◽  
Juvenile Males ◽  
Initial Capture

Livetrapping and removal trapping were used to monitor a population of Peromyscus leucopus. Breeding adult arid young of the year females averaged 2.0 and 1.1 litters per year, respectively. Nest mortality was 12–31%, while 58% of the juveniles disappeared within 2 weeks after weaning. The rate of disappearance of juvenile males (77%) was higher than that of juvenile females (44%); the greater loss of males was attributed to mortality. Loss of subadult and adult mice within 2 weeks after initial capture averaged 45 and 51%, respectively, and did not differ between the sexes. However, more males than females were recorded as entering the trapping grids, indicating that males tend to explore new areas more than females. Among resident mice, adult males had the highest rate of disappearance (0.31/week) while adult females had the lowest (0.05/week).

Population Dynamics of the Western Australian Soldier Crab Mictyris Occidentalis Unno, 2008 (brachyura, Mictyridae) in the Dampier Archipelago — 30 Years of Observations

Crustaceana ◽  
2011 ◽  
Vol 84 (8) ◽  
pp. 905-937 ◽  
Author(s):  
J. Unno ◽  
V. Semeniuk
Keyword(s):  
Population Dynamics ◽  
Maximum Size ◽  
First Year ◽  
Spatial And Temporal Variability ◽  
Adult Males ◽  
Population Densities ◽  
Juvenile Recruitment ◽  
Incremental Growth ◽  
Western Australian

AbstractThe previously undescribed population dynamics of the Western Australian soldier crab, Mictyris occidentalis Unno, 2008, in King Bay, north-western Australia are elucidated, with annual observations and sampling over a 30-year period from 1980 to 2010. This is the longest recorded study of a single inter-tidal brachyuran population and shows long-term persistence of soldier crab populations in stable, sheltered habitats. The life cycle of M. occidentalis follows a cryptic subsurface juvenile and immature adult (= adolescent) phase and an emergent adult phase. Population densities were generally 500 crabs/m2 for the early 1980s, late 1980s, and during the early 2000s. Maximum population densities were high in the mid 1980s (800 crabs/m2). The spatial and temporal variability in the distribution of the population was consistent over the study period. Juvenile recruitment extends for up to 7 months of a given year between May and November with the main influx of juveniles usually in June and occasional minor influxes in August or October. Juvenile recruitment is followed by incremental growth of individuals at a rate of 1 mm/month reaching sexual maturity in the first year at 6.0-6.9 mm carapace length (CL). Adult males are larger than females with a maximum size of 15.0 mm CL compared to 12.0 mm CL, respectively. Ovigerous females are low in numbers throughout most of the year but reach a peak in February. During swarming, M. occidentalis populations partition not only by size class, with surface crabs being adults only and subsurface crabs mainly adult females and juveniles, but also by sex in that swarms are male-dominated in varying ratios.

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