scholarly journals Arboreal aperitifs: Space use and activity of a major songbird nest predator in a tropical Thailand forest

2021 ◽  
Author(s):  
Anji D’souza ◽  
George Gale ◽  
Benjamin Michael Marshall ◽  
Daphawan Khamcha ◽  
Surachit Waengsothorn ◽  
...  
Keyword(s):  
Brownian Bridge ◽  
Radio Telemetry ◽  
Space Use ◽  
Evergreen Forest ◽  
Boiga Irregularis ◽  
Forest Fragment ◽  
Predator Species ◽  
Avian Nest ◽  
Nest Predator ◽  
Nesting Season

ABSTRACTPredator-prey interactions are fundamental drivers of population dynamics, yet rarely are both predator and prey species simultaneously studied. Despite being significant, widespread avian nest predators, research on the ecology of Southeast Asian snakes in relation to birds remains scarce. The green cat snake (Boiga cyanea) is a primary nest predator, responsible for ≈24% of forest songbird depredation in Northeast Thailand. We explored both diurnal and nocturnal movements of 14 (5 male, 9 female) adult B. cyanea with radio-telemetry for an average of 68 ± 16 days per individual, between 21 October 2017 and 8 June 2019 in the dry evergreen forest of the Sakaerat Biosphere Reserve (SBR). We quantified area of space use (ha) and activity through motion variance (Ϭm2) during the study period using dynamic Brownian bridge movement models, and linked our findings to a simultaneously-run avian nest monitoring study, initiated in 2013 within the same forest fragment. On average, movements, space use and activity differed between males and females, and between the avian nesting and non-nesting seasons. Males moved 51.37 m/day farther than females. They used areas 15.09 ha larger than females, and their activity was 3.91 Ϭm2 higher than that of females. In general, individuals moved 50.30 m/day farther during the nesting season than the non-nesting season. The snakes used areas 9.84 ha larger during the nesting season than the non-nesting season, and their activity during the nesting season was 3.24 Ϭm2 higher than that during the non-nesting season. All individuals were exclusively nocturnal, moving throughout the night, and often descending from higher diurnal refugia (>2 m) to forage closer to the ground after sunset. Boiga cyanea activity followed a similar trend to that of the recorded nest depredations at SBR. Our study links snake activity to nest depredations in SBR. Our openly-available data may yield further insight when combined with other major avian nest predator species like the congeneric invasive brown tree snake (Boiga irregularis) on the island of Guam.

scholarly journals Restricted constrictors: Space use and habitat selection of native Burmese pythons in Northeast Thailand

2020 ◽  
Author(s):  
Samantha Nicole Smith ◽  
Max Dolton Jones ◽  
Benjamin Michael Marshall ◽  
Surachit Waengsothorn ◽  
George A. Gale ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Animal Movement ◽  
Brownian Bridge ◽  
Radio Telemetry ◽  
Space Use ◽  
Population Level ◽  
Human Settlements ◽  
Small Areas ◽  
Agricultural Conversion ◽  
Selection Of

AbstractAnimal movement and resource use are tightly linked. Investigating these links to understand how animals utilize space and select habitats is especially relevant in areas that have been affected by habitat fragmentation and agricultural conversion. We set out to explore the space use and habitat selection of Burmese pythons (Python bivittatus) in a patchy land use matrix dominated by agricultural crops and human settlements. We used radio telemetry to record daily locations of seven Burmese pythons over the course of our study period of approximately 22 months. We created dynamic Brownian Bridge Movement Models (dBBMMs) for all individuals, using occurrence distributions to estimate extent of movements and motion variance to reveal temporal patterns. Then we used integrated step selection functions to determine whether individual movements were associated with particular landscape features (aquatic agriculture, forest, roads, settlements, terrestrial agriculture, water), and whether there were consistent associations at the population level. Our dBBMM estimates suggested that Burmese pythons made use of small areas (98.97 ± 35.42 ha), with low mean individual motion variance characterized by infrequent moves and long periods at a single location. At both the individual and population level, Burmese pythons in the agricultural matrix were associated with aquatic environments. Only one individual showed a strong avoidance for human settlements which is troublesome from a human-wildlife conflict angle, especially as Burmese pythons have been observed entering human settlements and consuming livestock in our study site. Our study is one of the first to contribute to the knowledge of Burmese python ecology in their native range as the majority of studies have focused on invasive populations.

scholarly journals Variable habitat selection and movement patterns among Bullsnake (Pituophis catenifer sayi) populations in Saskatchewan

2019 ◽  
Vol 132 (2) ◽  
pp. 126-139 ◽  
Author(s):  
Tera L. Edkins ◽  
Christopher M. Somers ◽  
Mark C. Vanderwel ◽  
Miranda J. Sadar ◽  
Ray G. Poulin
Keyword(s):  
Habitat Selection ◽  
Radio Telemetry ◽  
Geographic Location ◽  
Space Use ◽  
Fine Scale ◽  
Range Limit ◽  
Northern Range Limit ◽  
Range Overlap ◽  
Conservation Concern ◽  
River Valleys

Pituophis catenifer sayi (Bullsnake) is a sparsely studied subspecies of conservation concern in Canada. Basic ecological information is lacking for P. c. sayi, which reaches its northern range limit in western Canada. To address this gap, we used radio-telemetry to examine space use and habitat selection in three populations of Bullsnakes in disjunct river valley systems (Frenchman, Big Muddy, and South Saskatchewan River Valleys) across their Saskatchewan range. Bullsnakes in two valleys used up to three times more space, travelled 2.5-times farther from overwintering sites, and had lower home range overlap than the third population. Landscape-level habitat selection was flexible, with snakes in all populations using both natural and human-modified habitats most frequently. Fine-scale habitat selection was also similar among populations, with Bullsnakes selecting sites within 1 m of refuges, regardless of whether they were natural or anthropogenic. Based on these results, Bullsnakes are flexible in their broad scale habitat use, as long as they are provided with fine scale refuge sites. The distribution of key seasonal resources appears to ultimately determine space use and habitat selection by Bullsnakes, regardless of the geographic location of the population.

scholarly journals Defending against disparate marine turtle nest predators: nesting success benefits from eradicating invasive feral swine and caging nests from raccoons

Oryx ◽  
2014 ◽  
Vol 50 (2) ◽  
pp. 289-295 ◽  
Author(s):  
Richard M. Engeman ◽  
David Addison ◽  
J.C. Griffin
Keyword(s):  
Nest Predation ◽  
Sus Scrofa ◽  
Nesting Success ◽  
Marine Turtle ◽  
Financial Cost ◽  
Feral Swine ◽  
Predator Species ◽  
Marine Turtles ◽  
Nest Protection ◽  
Nesting Season

AbstractNest predation can threaten marine turtle nesting success, and having to address dissimilar predator species complicates nest protection efforts. On Florida's Keewaydin Island predation by raccoons Procyon lotor and invasive feral swine Sus scrofa are disparate, significant threats to marine turtle nests. Using 6 years of nesting data (mostly for loggerhead marine turtles Caretta caretta) we examined the impacts of swine predation on nests and the benefits of swine eradication, caging nests to protect them from raccoon predation, and the effects of nest caging on swine predation. Nest predation by swine began in mid nesting season 2007, after which swine quickly annihilated all remaining marine turtle nests. During 2005–2010 raccoon predation rates for caged nests (0.7–20.4%) were significantly lower than for uncaged nests (5.6–68.8%) in every year except 2009, when little raccoon predation occurred. The proportions of eggs lost from raccoon-predated nests did not differ between caged and uncaged nests. Caging did not prevent destruction by swine but median survival time for caged nests was 11.5 days longer than for uncaged nests, indicating that caged eggs in nests have a greater chance of hatching before being predated by swine. The financial cost of the eradication of swine greatly outweighed the value of hatchlings lost to swine predation in 2007.

Sexual and environmental variation in the space requirements of the Critically Endangered geometric tortoise, Psammobates geometricus

2012 ◽  
Vol 33 (2) ◽  
pp. 185-197 ◽  
Author(s):  
Margaretha Hofmeyr ◽  
Ulric van Bloemestein ◽  
Brian Henen ◽  
Craig Weatherby
Keyword(s):  
Home Range ◽  
Habitat Degradation ◽  
Space Use ◽  
Home Range Size ◽  
Home Ranges ◽  
Convex Polygons ◽  
Wet Season ◽  
Mating Opportunities ◽  
Space Requirements ◽  
Nesting Season

Psammobates geometricus has a limited distribution in the southwestern Cape, South Africa, where it occurs in small habitat fragments separated by agricultural and urban developments. Space use and its determining factors thus represent critical information for the effective conservation of this species. We used radiotelemetry and thread-trailing to study the movement patterns and space use of geometric tortoises over an annual cycle, and estimated home ranges with minimum convex polygons and fixed-kernel methods. Home range size of geometric tortoises showed large inter-individual variation, and for females, a positive relationship to body size. Females, the larger sex, had larger home ranges and mean daily displacements than males had. Female space use was high through most of the year, except in the wet season, when food was abundant, temperatures relatively low, and soft soils allowed easy nesting. Males used more space and displaced further in the non-nesting than nesting season, perhaps to optimise mating opportunities in the non-nesting season before females ovulate. Home ranges were more elongate and overlapped more in fallow fields than in natural vegetation, suggesting that habitat degradation alters home range structure. The space geometric tortoises used for their annual activities ranged from 1.02 to 44.85 ha. The large home ranges and effects of habitat degradation should influence the size of reserves, and the destiny of geometric tortoises in small habitat fragments.

scholarly journals Environmental Drivers of Fine-Scale Predator and Prey Spatial Dynamics in Sydney Harbour, Australia, and Adjacent Coastal Waters

2021 ◽  
Author(s):  
Yuri Niella ◽  
Amy F. Smoothey ◽  
Matthew D. Taylor ◽  
Victor M. Peddemors ◽  
Robert Harcourt
Keyword(s):  
Mixed Models ◽  
Visual Cues ◽  
Brownian Bridge ◽  
Spatial Dynamics ◽  
Space Use ◽  
Environmental Drivers ◽  
Predator Prey ◽  
Biological Variables ◽  
Carcharhinus Leucas ◽  
Additive Mixed Models

AbstractGreater Sydney is the largest coastal city in Australia and is where bull sharks (Carcharhinus leucas) are present every summer and autumn. A decade of acoustic telemetry data was used to identify drivers of space use for bull sharks and their potential prey, according to standardised 6-h intervals using dynamic Brownian bridge movement models. Influences of environmental, physical, and biological variables on the areas of space use, location, and predator–prey co-occurrence were investigated with generalised additive mixed models. Rainfall in the catchment affected space use for all animals (i.e. teleost species and both sexes of sharks), with varying temporal responses. Male sharks responded most promptly to high rainfall moving upstream in < 1 day, followed by teleosts (2 to 7 days), and female bull sharks after 4 days. Environmental luminosity affected male shark dispersal and space use, possibly indicating use of visual cues for foraging. Physical characteristics of habitat were important factors driving spatial overlaps between predator and prey in estuarine areas. In sandy embayments < 10-m deep, males and female bull sharks overlapped with different species, whereas males and silver trevally (Pseudocaranx georgianus) co-occurred in deep holes (> 30 m). Shark size influenced overlap between sexes, with smaller females less likely to co-occur with larger males (~ 50 cm). Variability in space use suggests spatial segregation by sex and size in bull sharks, with individuals targeting similar prey, yet either in different areas or at different times, ultimately enabling them to exploit different resources when in the same habitats.

Parent birds assess nest predation risk: influence of cavity condition and avian nest predator activity

2017 ◽  
Vol 48 (5) ◽  
pp. 691-699
Author(s):  
Jongmin Yoon ◽  
Jung-Shim Jung ◽  
Eun-Jin Joo ◽  
Byung-Su Kim ◽  
Shi-Ryong Park
Keyword(s):  
Predation Risk ◽  
Nest Predation ◽  
Avian Nest ◽  
Nest Predator

Predation on simulated duck nests in relation to nest density and landscape structure

2010 ◽  
Vol 37 (7) ◽  
pp. 597 ◽  
Author(s):  
Eliška Padyšáková ◽  
Martin Šálek ◽  
Lukáš Poledník ◽  
František Sedláček ◽  
Tomáš Albrecht
Keyword(s):  
Survival Rates ◽  
Predation Rate ◽  
High Density ◽  
Nest Density ◽  
Predator Species ◽  
Density Dependent ◽  
Landscape Type ◽  
Mammalian Predators ◽  
Littoral Vegetation ◽  
Nest Predator

Context Density-dependent predation has been recently discussed as a contributing cause of duck nest failure. Aims We tested whether nest density increases the nest predation rate (density-dependent predation) in patches of littoral vegetation surrounding fishponds in two contrasting landscape types, the first dominated by forest and the other dominated by agricultural fields. Methods In total, 576 simulated ground nests were deployed in 48 littoral patches in South Bohemia, Czech Republic, in two replicates (June and July), for two consecutive years (2005 and 2006). Nests were deployed either solitarily (low-density plots) or in groups of five nests (high-density plots). Key results Despite differences in local predator communities, we found no evidence of different survival rates of solitary nests and nests placed in high-density patches in either habitat. Mammalian predators were the most common nest predators, followed by birds. The composition of nest predator community depended on landscape type, with mammals predominating in forest landscape and birds in agricultural areas. Our data thus do not support the theory of density-dependent predation of duck nests in littoral patches, regardless of predominant nest predator type. Conclusions Based on our results, we conclude that nest predator responses to different habitats are complex, taxon specific, and context dependent. Implications Conservation efforts for waterfowl may need to be customised according to the nest-predator species primarily responsible for local nest mortality and the nature of the landscape mosaic.

scholarly journals A new phytotelm-breeding treefrog of the genus Nasutixalus (Rhacophoridae) from western Yunnan of China

Zootaxa ◽  
2018 ◽  
Vol 4388 (2) ◽  
pp. 191 ◽  
Author(s):  
JIAN-HUAN YANG ◽  
BOSCO PUI-LOK CHAN
Keyword(s):  
New Species ◽  
Evergreen Forest ◽  
Adult Males ◽  
Forest Fragment ◽  
Single Female ◽  
Upper Eyelid ◽  
Western Yunnan ◽  
Tree Holes ◽  
Established Genus ◽  
Montane Rainforest

A new treefrog of the genus Nasutixalus is described from montane evergreen forest in Yingjiang County, in western Yunnan, China. The new species, Nasutixalus yingjiangensis sp. nov., can be distinguished from its congeners by a combination of the following characters: medium body size (SVL 39.5–40.0 mm in adult males, 47.5 mm in a single female); tympanum indistinct and covered with tubercles; disc diameter of third finger greater than tympanum diameter; dorsal skin relatively smooth, scattered with small tubercles, those on head and anterior dorsum of body more dense and more prominent; light brown above with a dark brown marking between eyes and two broad dark brown lateral strips on the dorsum; iris with a weak “X”-shaped, light colored marking; interorbital distance shorter than the upper eyelid width; comparatively short foot (mean TFL/SVL ratio 67.0% and 62.9% in males and female respectively). The new species appears to be forest-dependent and was found in well-preserved montane rainforest; it inhabits the canopy and breeds in tree holes during the rainy season. The type locality of the new species is an isolated forest fragment surrounded by degraded landscape and efforts are already underway to protect the site. Nasutixalus yingjiangensis sp. nov. represents the third known species of the newly established genus Nasutixalus. 

Gap-crossing by Wood Thrushes (Hylocichla mustelina)in a fragmented landscape

2011 ◽  
Vol 89 (11) ◽  
pp. 1091-1097 ◽  
Author(s):  
T. MacIntosh ◽  
B.J.M. Stutchbury ◽  
M.L. Evans
Keyword(s):  
Radio Telemetry ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Hylocichla Mustelina ◽  
Continuous Forest ◽  
Migratory Songbirds ◽  
Gap Crossing ◽  
Wood Thrushes ◽  
Gap Width

We used radio-telemetry to study the movement patterns of Wood Thrushes ( Hylocichla mustelina (J.F. Gmelin, 1789)) occupying small forest fragments (<5 ha) to examine gap-crossing between fragments and edge use within fragments. We found that 82% (8/11) of males and 33% (2/6) of females made at least one foray off of its resident forest fragment and we documented a total of 26 off-fragment forays (n = 79 h tracking). Males spent, on average, 23.5% of their time off their fragment, while females were gone 12.8% of the time tracked. Most forays were >150 m in distance and foray rate to adjacent fragments declined with increasing gap width. Males on fragments spent more time off their territory (23.5%) and traveled farther (392 m) than males occupying territories within a continuous forest (4.8% and 99 m, respectively). In fragments, 10 out of 17 individuals spent >80% of their time within 20 m of the fragment edge and edge use was significantly more than expected based on the amount of edge available in each fragment. This study adds to the growing evidence for migratory songbirds that during the breeding season, forest fragmentation may increase rather than impede daily movements.

scholarly journals Nonchalant neighbours: Space use and overlap of the critically endangered elongated tortoise

2020 ◽  
Author(s):  
Matt Ward ◽  
Benjamin Michael Marshall ◽  
Cameron Hodges ◽  
Ysabella Montano ◽  
Taksin Artchawakom ◽  
...  
Keyword(s):  
Protected Area ◽  
Animal Movement ◽  
Radio Telemetry ◽  
Biosphere Reserve ◽  
Space Use ◽  
Critically Endangered ◽  
Interactive Effects ◽  
Conspecific Attraction ◽  
Interaction Patterns ◽  
Female Attraction

To prevent population extirpations we need to understand species’ requirements, especially for critically endangered species inhabiting biodiversity hotspots. Studying animal movement provides insights into such requirements and gauges protected area effectiveness. Southeast Asian protected areas are becoming isolated; thus, we must ensure existing areas can sustain populations. We used multi-year radio-telemetry with the critically endangered Elongated Tortoise (Indotestudo elongata) to assess: movements, space-use, and conspecific overlap in a small protected area –Sakaerat Biosphere Reserve, Thailand. Movements were weakly seasonal, increasing in hot and wet seasons compared to the dry season. Individuals annual space-use varied (4.24–55.57 ha), while frequently overlapping with conspecifics. Conspecific comparisons revealed males (n = 5) moved similarly to females (n = 12) but used larger areas. Explorations of temporal avoidance versus attraction reveal more instances of conspecific attraction than avoidance (20:8). Avoidance/attraction behaviour appeared disconnected from carapace length or mass; therefore, that conspecific interaction patterns may potentially be a result of resources (mates or food) rather than competition (i.e., no apparent evidence of smaller individuals avoiding larger individuals). Female-female attraction suggests an absence of resource exclusion tactics at the temporal resolution of our data. Male-female attraction may indicate reproductive movements coinciding with hot season, but we failed to detect significant interactive effects linking conspecific attraction or step length to proximity to breeding activity. Our observations of annual space-use and space overlap present critical components when designing robust population assessments; assessments that will underline any successful I. elongata conservation effort. When considered in the context of previous work connecting space overlap with population viability, our results suggest the biosphere population of I. elongata to be reproductive, with enough resources to be potentially viable; the findings help emphasise the importance of even relatively small protected natural areas.

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