Estimating density of terrestrial reptiles in forest habitats: the importance of considering availability in distance sampling protocols

SummaryThe Red-knobbed Hornbill Rhyticeros cassidix and the Sulawesi Tarictic Hornbill Penelopides exarhatus are endemic to Sulawesi. This study assessed the effect of anthropogenic disturbance on these two species in Lambusango forest, Buton, south-east Sulawesi. Data were collected between 2005 and 2007 in six study sites which varied in their levels of disturbance. Two of the lightly disturbed and two of the more heavily disturbed sites were within ‘protection forest’ whereas the rest were classified as ‘production forest’. We used point counts with distance sampling to survey the hornbills. Habitat data were also collected at each of the points and related to hornbill ‘occupancy’ with the program PRESENCE. Both hornbills were estimated to be at higher density in the lightly disturbed forest but the level of disturbance had more of a detrimental effect on Red-knobbed Hornbill than on Sulawesi Tarictic Hornbill. Lightly disturbed forest had significantly more large trees than the heavily disturbed forest but there was no difference in the abundance of figs. Using four covariates (disturbance level, protection status, number of large trees, and number of figs), 99% of presence/absence of Red-knobbed Hornbills at the points could be explained by habitat disturbance and 87% by forest status; the same covariates explained 76% of presence/absence for the Sulawesi Tarictic Hornbill with abundance of large trees as the most important factor. These results support the notion that Red-knobbed Hornbill is more sensitive to anthropogenic disturbance and its conservation is highly dependent upon the preservation of forest habitats with low levels of disturbance.

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Compliance with Saliva Sampling Protocols: Electronic Monitoring Reveals Invalid Cortisol Daytime Profiles in Noncompliant Subjects

PsycEXTRA Dataset ◽

10.1037/e413812005-399 ◽

2002 ◽

Author(s):

Brigitte M. Kudielka ◽

Clemens Kirschbaum

Keyword(s):

Electronic Monitoring ◽

Sampling Protocols

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Reduced sampling protocols in estimation of insulin sensitivity and glucose effectiveness using the minimal model in NIDDM

Diabetes ◽

10.2337/diabetes.42.11.1635 ◽

1993 ◽

Vol 42 (11) ◽

pp. 1635-1641 ◽

Cited By ~ 3

Author(s):

P. A. Coates ◽

R. L. Ollerton ◽

S. D. Luzio ◽

I. S. Ismail ◽

D. R. Owens

Keyword(s):

Insulin Sensitivity ◽

Minimal Model ◽

Glucose Effectiveness ◽

Sampling Protocols

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Applications of GIS, Advanced Sensors and Habitat Modeling in Support of Desert Tortoise Line Distance, Sampling and Translocation Studies Related to the Proposed Expansion of the Ft. Irwin NTC

10.21236/ada498532 ◽

2008 ◽

Author(s):

Jordan Henk

Keyword(s):

Distance Sampling ◽

Habitat Modeling ◽

Desert Tortoise

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Using Landscape Change Analysis and Stakeholder Perspective to Identify Driving Forces of Human–Wildlife Interactions

Land ◽

10.3390/land10020146 ◽

2021 ◽

Vol 10 (2) ◽

pp. 146

Author(s):

Mihai Mustățea ◽

Ileana Pătru-Stupariu

Keyword(s):

Landscape Change ◽

Ursus Arctos ◽

Driving Forces ◽

Brown Bear ◽

Mountain Range ◽

Change Analysis ◽

Local Stakeholders ◽

Stakeholder Perspective ◽

Forested Ecosystems ◽

Forest Habitats

Human–wildlife interactions (HWI) were frequent in the post-socialist period in the mountain range of Central European countries where forest habitats suffered transitions into built-up areas. Such is the case of the Upper Prahova Valley from Romania. In our study, we hypothesized that the increasing number of HWI after 1990 could be a potential consequence of woodland loss. The goal of our study was to analyse the effects of landscape changes on HWI. The study consists of the next steps: (i) applying 450 questionnaires to local stakeholders (both citizens and tourists) in order to collect data regarding HWI temporal occurrences and potential triggering factors; (ii) investigating the relation between the two variables through the Canonical Correspondence Analysis (CCA); (iii) modelling the landscape spatial changes between 1990 and 2018 for identifying areas with forest loss; (iv) overlapping the distribution of both the households affected by HWI and areas with loss of forested ecosystems. The local stakeholders indicate that the problematic species are the brown bear (Ursus arctos), the wild boar (Sus scrofa), the red fox (Vulpes vulpes) and the grey wolf (Canis lupus). The number of animal–human interactions recorded an upward trend between 1990 and 2018, and the most significant driving factors were the regulation of hunting practices, the loss of habitats, and artificial feeding. The landscape change analysis reveals that between 1990 and 2018, the forest habitats were replaced by built-up areas primarily on the outskirts of settlements, these areas coinciding with frequent HWI. The results are valid for both forest ecosystems conservation in the region, wildlife management, and human infrastructures durable spatial planning.

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Getting the Most From Surveys: How Method Selection and Method Modification Impact Butterfly Survey Data

Annals of the Entomological Society of America ◽

10.1093/aesa/saab004 ◽

2021 ◽

Author(s):

Katherine C Kral-O’Brien ◽

Adrienne K Antonsen ◽

Torre J Hovick ◽

Ryan F Limb ◽

Jason P Harmon

Keyword(s):

Species Richness ◽

New Species ◽

Count Data ◽

Distance Sampling ◽

Line Transect ◽

Similar Species ◽

Method Selection ◽

M 10 ◽

Sampling Procedures

Abstract Many methods are used to survey butterfly populations, with line transect and area surveys being prominent. Observers are typically limited to search within 5 or 10 m from the line, while observers are unrestricted in larger specified search regions in area surveys. Although methods differ slightly, the selection is often based on producing defendable data for conservation, maximizing data quality, and minimizing effort. To guide method selection, we compared butterfly surveys using 1) line versus area methods and 2) varying width transects (5 m, 10 m, or unrestricted) using count data from surveys in North Dakota from 2015 to 2018. Between line and area surveys, we detected more individuals with area surveys, even when accounting for effort. However, both methods accumulated new species at similar rates. When comparing transect methodology, we detected nearly 60% more individuals and nine more species when transect width increased from 5 m to unrestricted, despite similar effort across methodology. Overall, we found line surveys slightly less efficient at detecting individuals, but they collected similar species richness to area surveys when accounting for effort. Additionally, line surveys allow the use of unrestricted-width transects with distance sampling procedures, which were more effective at detecting species and individuals while providing a means to correct count data over the same transect length. Methods that reduce effort and accurately depict communities are especially important for conservation when long-term datasets are unavailable.

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Divergent Adaptation Strategies of Vascular Facultative Epiphytes to Bark and Soil Habitats: Insights from Stoichiometry

Forests ◽

10.3390/f12010016 ◽

2020 ◽

Vol 12 (1) ◽

pp. 16

Author(s):

Tingting Zhang ◽

Wenyao Liu ◽

Tao Hu ◽

Dandan Tang ◽

Yuxuan Mo ◽

...

Keyword(s):

Elemental Composition ◽

Forest Ecosystems ◽

Adaptation Strategies ◽

P Elements ◽

Nutritional Conditions ◽

Variable Element ◽

C:P Ratios ◽

Strong Control ◽

Forest Habitats ◽

Cultivation Experiment

Understanding the stoichiometric traits of plants is critical for studying their ecological adaptation strategies. Facultative epiphytes (which can also live on the ground) are an important component of epiphytic flora of montane forest ecosystems. However, a key gap persists in our understanding how facultative epiphytes can adapt different nutritional conditions of ground and canopy habitats? To study adaptive strategies of facultative epiphytes and the characteristics of the content and stoichiometric homeostasis of C, N, and P elements, we conducted a field experiment and a greenhouse N and P additions cultivation experiment. We found that epiphytic individuals of facultative epiphytes showed lower C:N and C:P ratios, higher variation in elemental composition, and more pronounced N limitation than terrestrial individuals. Moreover, facultative epiphytes showed strong control over the elemental composition of leaves, and their stoichiometric homeostasis of leaves and stems were stronger than roots. Furthermore, the homeostasis of facultative epiphytes decreased in the order N > P. Our results indicated that epiphytic and terrestrial individuals of facultative epiphytes have difference in nutrient limitation, and they use plastic strategies in different habitats. Epiphytic individuals survive in the intermittent habitat through luxury consumption of nutrient while terrestrial individuals were relatively conservative nutrient users. Furthermore, our results implied that facultative epiphytes maintain stable metabolic leaf activity via variable element concentrations of roots to adapt to highly heterogeneous forest habitats.

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Spatial distribution of the Barbary Partridge (Alectoris barbara) in Sardinia explained by land use and climate

European Journal of Wildlife Research ◽

10.1007/s10344-021-01519-w ◽

2021 ◽

Vol 67 (4) ◽

Author(s):

Gianpasquale Chiatante ◽

Marta Giordano ◽

Anna Vidus Rosin ◽

Oreste Sacchi ◽

Alberto Meriggi

Keyword(s):

Land Use ◽

Conservation Status ◽

Distance Sampling ◽

Strong Relationship ◽

European Population ◽

Factors Affecting ◽

Brood Rearing ◽

Management Actions ◽

Negative Effect ◽

Study Sites

AbstractMore than half of the European population of the Barbary Partridge is in Sardinia; nonetheless, the researches concerning this species are very scarce, and its conservation status is not defined because of a deficiency of data. This research aimed to analyse the habitat selection and the factors affecting the abundance and the density of the Barbary Partridge in Sardinia. We used the data collected over 8 years (between 2004 and 2013) by spring call counts in 67 study sites spread on the whole island. We used GLMM to define the relationships between the environment (topography, land use, climate) both the occurrence and the abundance of the species. Moreover, we estimated population densities by distance sampling. The Barbary Partridge occurred in areas at low altitude with garrigue and pastures, avoiding woodlands and sparsely vegetated areas. We found a strong relationship between the occurrence probability and the climate, in particular, a positive relation with temperature and a negative effect of precipitation, especially in April–May, during brood rearing. Furthermore, dry crops positively affected the abundance of the species. We estimated a density of 14.1 partridges per km2, similar to other known estimates. Our findings are important both because they increase the knowledge concerning this species, which is considered data deficient in Italy, and because they are useful to plan management actions aimed to maintain viable populations if necessary.

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Bridled Quail-dove Geotrygon mystacea population assessment after hurricanes Irma and Maria, St. Eustatius, Caribbean Netherlands

Bird Conservation International ◽

10.1017/s0959270920000647 ◽

2021 ◽

pp. 1-12

Author(s):

FRANK F. RIVERA-MILÁN ◽

HANNAH MADDEN ◽

KEVIN VERDEL

Keyword(s):

National Park ◽

Food Limitation ◽

Distance Sampling ◽

Population Status ◽

Management Actions ◽

Abundance Estimates ◽

Detection Mode ◽

Limited Food ◽

Seed Eating ◽

Free Ranging

Summary Structural vegetation damage and food limitation are important effects of major hurricanes, particularly for fruit/seed-eating, forest-dependent Caribbean birds with restricted distributions and small populations, such as the Bridled Quail-dove Geotrygon mystacea. Motivated by the lack of abundance estimates, corrected for detection probability, we conducted distance-sampling surveys inside and outside the Quill National Park each May in 2016-2019. Detection mode was the most important covariate, with others receiving no support from the data. Detectability of available single individuals and clusters of individuals within 60 m of transect centrelines averaged 0.957 ± 0.114 standard error for audio detections, 0.434 ± 0.052 for visual detections, and 0.693 ± 0.064 for detection modes combined. Availability averaged 0.475 ± 0.138 and the product of detectability and availability averaged 0.329 ± 0.098. Density averaged 1.459 ± 0.277 individuals ha-1 and population size averaged 642 ± 122 individuals in 440 ha. Density did not differ along and away from forest trails, but was higher inside than outside the park and at elevations within 201-400 m than 100-200 m and 401-600 m. Density declined by 76% after hurricanes Irma and Maria in 2017. We suggest that major hurricanes together with free-ranging livestock overgrazing degraded foraging habitats, limited food supply, and caused a population bottleneck. Our methodology can be implemented across the distribution range to assess population status and trends and evaluate the result of management actions at key conservation sites. Bridled Quail-dove populations probably were declining on most islands before the 2017 hurricanes and population status warrants revision.

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Evaluating Alternative Flight Plans in Thermal Drone Wildlife Surveys—Simulation Study

Remote Sensing ◽

10.3390/rs13061102 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1102

Author(s):

Julia Witczuk ◽

Stanisław Pagacz

Keyword(s):

Computer Simulations ◽

Survey Design ◽

Distance Sampling ◽

Line Of Sight ◽

Density Estimates ◽

Accuracy And Precision ◽

Survey Costs ◽

Random Survey ◽

Density Population

The rapidly developing technology of unmanned aerial vehicles (drones) extends to the availability of aerial surveys for wildlife research and management. However, regulations limiting drone operations to visual line of sight (VLOS) seriously affect the design of surveys, as flight paths must be concentrated within small sampling blocks. Such a design is inferior to spatially unrestricted randomized designs available if operations beyond visual line of sight (BVLOS) are allowed. We used computer simulations to assess whether the VLOS rule affects the accuracy and precision of wildlife density estimates derived from drone collected data. We tested two alternative flight plans (VLOS vs. BVLOS) in simulated surveys of low-, medium- and high-density populations of a hypothetical ungulate species with three levels of effort (one to three repetitions). The population density was estimated using the ratio estimate and distance sampling method. The observed differences in the accuracy and precision of estimates from the VLOS and BVLOS surveys were relatively small and negligible. Only in the case of the low-density population (2 ind./100 ha) surveyed once was the VLOS design inferior to BVLOS, delivering biased and less precise estimates. These results show that while the VLOS regulations complicate survey logistics and interfere with random survey design, the quality of derived estimates does not have to be compromised. We advise testing alternative survey variants with the aid of computer simulations to achieve reliable estimates while minimizing survey costs.

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