scholarly journals Adaptive foraging strategy of an insular snake (Lycodon semicarinatus, Colubridae) feeding on patchily distributed nests of sea turtles

Behaviour ◽  
2021 ◽  
pp. 1-31
Author(s):  
Kazumasa Matsumoto ◽  
Akira Mori
Keyword(s):  
Sea Turtles ◽  
Fine Sand ◽  
Foraging Strategy ◽  
Optimal Time ◽  
Foraging Mode ◽  
Okinawa Island ◽  
Foraging Tactics ◽  
The Difference ◽  
Adaptive Foraging ◽  
Active Searching

Abstract Foraging tactics of predators generally include two major modes, active searching and ambushing. A colubrid snake, Lycodon semicarinatus, is a typical example of a predator, which uses both tactics to forage on sea turtles on islands of the Kerama Group in the Central Ryukyu Archipelago, Japan. To investigate factors that determine the foraging mode of this snake, we conducted a four-year field survey on its foraging behaviour on sea turtles on another island, Okinawa Island. We found that the snake performs only active searching at our study site. Snakes visited a small area exactly above the nest of sea turtles and attempted to burrow a tunnel to feed on eggs and hatchlings in the sand. Tunnels leading from the surface of the beach to the inside of the nest were formed only by large snakes. Many other snakes used the already made tunnels to capture eggs and hatchlings in the nest. When the snakes caught a hatchling, they brought the hatchling away into the nearby bush area without swallowing it above the nest (taking-away behaviour). When snakes failed to find food on a nest, they terminated the intensive search above the nest in approximately 5 minutes irrespective of snake body size, season, and the condition of the nest. Subsequently, they left the nest and resumed extensive searching for other nests. Our findings showed that L. semicarinatus has a different foraging strategy depending on populations. Two environmental traits, diversity of available prey animals other than sea turtles and characteristics of sand that beaches consist of, were considered as factors that might cause the difference in the foraging strategy. The fine sand of our study site enables snakes to form a sturdy tunnel in nests. We presume that such an environment facilitates the use of active searching by the snakes to find the nest with tunnels suitable for exploitation. The taking-away behaviour may be effective to reduce excessive contact with other conspecifics under the situation that the nest with tunnels attracts many visitors. Furthermore, the observation that the snake left the nest site after a consistent duration of unprofitable searching supports the giving-up time rule, which has been predicted by a theoretical model concerning the optimal time for predators to leave a patch.

scholarly journals Diversity of feeding strategies in loggerhead sea turtles from the Cape Verde archipelago

2019 ◽  
Vol 166 (10) ◽  
Author(s):  
Sahmorie J. K. Cameron ◽  
Miguel Baltazar-Soares ◽  
Victor A. Stiebens ◽  
Thomas Reischig ◽  
Sandra M. Correia ◽  
...  
Keyword(s):  
Feeding Strategy ◽  
Sea Turtles ◽  
Foraging Strategy ◽  
West African ◽  
Cape Verde ◽  
Feeding Strategies ◽  
Adaptive Potential ◽  
Loggerhead Sea Turtles ◽  
Carbon And Nitrogen ◽  
Upwelling Area

Abstract As biodiversity worldwide is decreasing, to preserve adaptive potential, the importance of maintaining species’ genetic and trait diversities is increasing. An efficient foraging strategy is a critical trait for an organism’s fitness, as it affects its physiology and reproduction. Understanding such strategies is especially relevant for species with long feeding migrations such as sea turtles. Using carbon and nitrogen stable isotopes combined with mitochondrial sequencing, we explored the diversity of feeding strategies in genetically differentiated nesting groups of loggerhead sea turtles (Caretta caretta) within the Cape Verde Archipelago. Here, we reveal a pattern where turtles from most islands use two distinct oceanic feeding strategies, including one putatively linked to a 15N-enriched zone of the West African upwelling area. On the Eastern island of Boavista, an additional third strategy exists used by turtles feeding mostly neritically. Contrary to previous paradoxical assumptions, oceanic turtles, that represent the vast majority of the population, are not smaller than neritic turtles and therefore do not seem to feed in a suboptimal environment. Our results also suggest that the number of feeding strategies may correlate with demography, whereby a greater feeding strategy diversity matches demographic signs of recent expansion after a population bottleneck for turtles nesting on the island of Boavista. Overall, the feeding ecology of Cape Verde loggerhead turtles is complex and likely shaped by an interaction between environmental and population parameters. Our results stress the importance of conservation efforts to prevent loss of critical diversity in endangered species.

Intertidal foraging by gentoo penguins in a macroalgal raft

2020 ◽  
Vol 32 (1) ◽  
pp. 43-44
Author(s):  
James B. McClintock ◽  
Charles D. Amsler ◽  
Margaret O. Amsler ◽  
William R. Fraser
Keyword(s):  
Environmental Change ◽  
Foraging Behaviour ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Marion Island ◽  
Pygoscelis Papua ◽  
General Consensus ◽  
Foraging Tactics ◽  
Pygoscelid Penguins ◽  
Foraging Tactic

Foraging strategies in gentoo penguins (Pygoscelis papua) have been well studied (e.g. Croxall et al. 1988, Robinson & Hindell 1996, Lescroël et al. 2004, Takahashi et al. 2008, Xavier et al. 2017). The general consensus is this largest member of the three pygoscelid penguins displays both nearshore benthic and pelagic foraging tactics to consume combinations of crustaceans and fish. In a recent study, Carpenter-Kling et al. (2017) reported that gentoos at sub-Antarctic Marion Island displayed a novel foraging strategy that consisted of alternating typical lengthy foraging trips with much shorter nearshore afternoon trips. They suggest the latter foraging behaviour may be a response to suboptimal feeding conditions caused by local environmental change. This novel discovery reinforces the fact that, despite considerable study, not all foraging tactics in penguins have been documented. In this paper, we describe what we believe to be, yet another undocumented foraging tactic employed by gentoos.

scholarly journals Draft Whole Genome Sequence Analyses on Pseudomonas syringae pv. actinidiae Hypersensitive Response Negative Strains Detected from Kiwifruit Bleeding Sap Samples

2018 ◽  
Vol 108 (5) ◽  
pp. 552-560 ◽  
Author(s):  
Enrico Biondi ◽  
Alan Zamorano ◽  
Ernesto Vega ◽  
Stefano Ardizzi ◽  
Davide Sitta ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Genome Sequence ◽  
Hypersensitive Response ◽  
Time Window ◽  
Gene Clusters ◽  
Whole Genome Sequence ◽  
Optimal Time ◽  
Whole Genome ◽  
Isolation And Identification ◽  
The Difference

Kiwifruit bleeding sap samples, collected in Italian and Chilean orchards from symptomatic and asymptomatic plants, were evaluated for the presence of Pseudomonas syringae pv. actinidiae, the causal agent of bacterial canker. The saps were sampled during the spring in both hemispheres, before the bud sprouting, during the optimal time window for the collection of an adequate volume of sample for the early detection of the pathogen, preliminarily by molecular assays, and then through its direct isolation and identification. The results of molecular analyses showed more effectiveness in the P. syringae pv. actinidiae detection when compared with those of microbiological analyses through the pathogen isolation on the nutritive and semiselective media selected. The bleeding sap analyses allowed the isolation and identification of two hypersensitive response (HR) negative and hypovirulent P. syringae pv. actinidiae strains from different regions in Italy. Moreover, multilocus sequence analysis (MLSA) and whole genome sequence (WGS) were carried out on selected Italian and Chilean P. syringae pv. actinidiae virulent strains to verify the presence of genetic variability compared with the HR negative strains and to compare the variability of selected gene clusters between strains isolated in both countries. All the strains showed the lack of argK and coronatine gene clusters as reported for the biovar 3 P. syringae pv. actinidiae strains. Despite the biologic differences obtained in the tobacco bioassays and in pathogenicity assays, the MLSA and WGS analyses did not show significant differences between the WGS of the HR negative and HR positive strains; the difference, on the other hand, between PAC_ICE sequences of Italian and Chilean P. syringae pv. actinidiae strains was confirmed. The inability of the hypovirulent strains IPV-BO 8893 and IPV-BO 9286 to provoke HR in tobacco and the low virulence shown in this host could not be associated with mutations or recombinations in T3SS island.

scholarly journals DIALYSIS START TIMING: DEVELOPMENT AND VALIDATION OF START SCORING SCALE

2018 ◽  
Vol 20 (2) ◽  
pp. 47-60 ◽  
Author(s):  
A. Yu. Zemchenkov ◽  
R. P. Gerasimchuk ◽  
A. B. Sabodash ◽  
K. A. Vishnevskii ◽  
G. A. Zemchenkov ◽  
...  
Keyword(s):  
Decision Making ◽  
Mortality Risk ◽  
Mortality Prediction ◽  
Validation Dataset ◽  
Optimal Time ◽  
Survival Prediction ◽  
Diabetes Status ◽  
The Difference ◽  
Validation Set ◽  
And Gender

Aim.The optimal time for initiating of chronic dialysis remains unknown. The scale for mortality risk assessment could help in decision-making concerning dialysis start timing.Methods.We randomly divided 1856 patients started dialysis in 2009–2016 into developmental and validation group (1:1) to create and validate scoring system «START» predicting mortality risk at dialysis initiation in order to fi nd unmodifi able and modifi able factors which could help in the decision-making of dialysis start. In the series of univariate regression models in the developmental set, we evaluated the mortality risk linked with available parameters: age, eGFR, serum phosphate, total calcium, hemoglobin, Charlson comorbidity index, diabetes status, urgency of start (turned to be signifi cant) and gender, serum sodium, potassium, blood pressure (without impact on survival). Similar hazard ratios were converted to score points.Results.The START score was highly predictive of death: C-statistic was 0.82 (95% CI 0.79–0.85) for the developmental dataset and 0.79 (95% CI 0.74–0.84) for validation dataset (both p < 0.001). On applying the cutoff between 7–8 points in the developmental dataset, the risk score was highly sensitive 81.1% and specifi c 67.9%; for validation dataset, the sensitivity was 78.9%, specifi city 67.9%. We confi rmed the similarity in survival prediction in the validation set to developmental set in low, medium and high START score groups. The difference in survival between three levels of START-score in validation set remained similar to that of developmental set: Wilcoxon = 8.78 (p = 0.02) vs 15.31 (p < 0.001) comparing low–medium levels and 25.18 (p < 0.001) vs 39.21 (p < 0.001) comparing medium–high levels.Conclusion.Developed START score system including modifi able factors showed good mortality prediction and could be used in dialysis start decision-making. 

Efficacy of dart-delivered PZP-22 immunocontraceptive vaccine in wild horses (Equus caballus) in baited traps in New Mexico, USA

2019 ◽  
Vol 46 (8) ◽  
pp. 713
Author(s):  
Kathleen A. Carey ◽  
Alexa Ortiz ◽  
Kayla Grams ◽  
Dan Elkins ◽  
John W. Turner Jr ◽  
...  
Keyword(s):  
New Mexico ◽  
Optimal Time ◽  
Delivery Methods ◽  
Exact Test ◽  
Wild Horse ◽  
Baited Traps ◽  
Antibody Titers ◽  
The Difference ◽  
Historical Management ◽  
Immunocontraceptive Vaccine

Abstract Context Federally protected wild horses on public lands are undergoing population growth that overwhelms the historical management strategy of removal and adoption. Porcine zona pellucida (PZP) has been used as an injectable immunocontraceptive vaccine to induce reversible infertility in free-roaming horses. PZP vaccination during February and March, which is the optimal time for administering current vaccines, is not possible for the herd on Jarita Mesa Wild Horse Territory (JM WHT), New Mexico, due to severe weather, terrain and subject wariness. AimsThe first goal was to assess bait trapping and remote darting as a minimally disruptive alternative to helicopter gathers for treatment. The second goal was to quantify the efficacy over 2 years following spring treatment with a single injection of PZP-22 (a combination of PZP-adjuvant emulsion and controlled-release pellets) by remote dart delivery. Methods Bait trapping and dart delivery of PZP-22 was carried out on JM WHT from 4 April to 16 June 2012. The herd was observed in the summers of 2011, 2013 and 2014 to determine the foaling status of the study mares. Outcome (foal or no foal) as a function of treatment was analysed using Fisher’s exact test. Key resultsThere were 157 individuals, including 66 females &gt;1 year old, documented in 2011. In 2012, 26 females (including three yearlings) identified by colour and markings were bait trapped and darted with PZP-22. The proportion of treated females foaling was lower than that of untreated females in 2013 and 2014, but the difference was only significant in 2013. Of the treated mares observed in 2013, the two that foaled were the last two treated in 2012. Untreated mares &gt;4 years old were significantly more likely to foal than younger mares. Conclusions Bait trapping at JM WHT permitted successful delivery of PZP-22 in a previously inaccessible herd. Dart administration of PZP-22 in April–June induced at least 1 year of measurable infertility. Implications This is the first demonstration of the efficacy of an initial treatment of PZP-22 delivered by dart instead of hand injection. Considerations for PZP-22 treatment include seasonal timing of treatments and age of treated mares. Treatments need to take place early enough to allow antibody titers to build to contraceptive levels before the breeding season.

scholarly journals Diel variation in abundance and size of the seabob shrimp Xiphopenaeus kroyeri (Crustacea, Penaeoidea) in the Ubatuba region, Southeastern Brazil

2010 ◽  
Vol 82 (2) ◽  
pp. 369-378 ◽  
Author(s):  
Sabrina M. Simões ◽  
Rogerio C. Costa ◽  
Adilson Fransozo ◽  
Antonio L. Castilho
Keyword(s):  
Fine Sand ◽  
Catch Rate ◽  
Southeastern Brazil ◽  
Sediment Type ◽  
Diel Variation ◽  
Xiphopenaeus Kroyeri ◽  
Mean Size ◽  
The Difference ◽  
Student’S T ◽  
Year 2000

The objective of the present study was to analyze diel variation in the abundance and size of the seabob shrimp Xiphopenaeus kroyeri in the Ubatuba region, state of São Paulo, during the year 2000. In each season of the year, collections were made in the day and at night on 9 transects at depths ranging from 2 to 40 m. The estimated shrimp amount was of 28,878 individuals. Although the catch rate was higher during the day (15,853 shrimp), this did not differ significantly from the catch at night (13,025). The catch rate was higher in daytime on most transects, but was higher at night at locations where fine and very fine sand predominated. The majority of juveniles were caught during the day. The mean size (CL) was 14.43 ± 4.02 mm for day and 14.82 ± 4.28 mm for night samples, and the difference was significant (Student's t-test, df = 2, 429, t = 2.27, p = 0.02). The largest individuals were caught during the night. None of the three models that have been proposed in the literature to account for differences in the diurnal catch pattern of penaeid species can be applied to X. kroyeri. Our results provide evidence that sediment type not only influenced the catch rate in the analyzed periods, but also determined which models might fit the behavior of this species.

Long-Term Trends in Prehistoric Fishing and Hunting on Tobago, West Indies

2006 ◽  
Vol 17 (3) ◽  
pp. 316-334 ◽  
Author(s):  
David W. Steadman ◽  
Sharyn Jones
Keyword(s):  
Species Richness ◽  
Relative Abundance ◽  
West Indies ◽  
Sea Turtles ◽  
Food Preferences ◽  
Reef Fishes ◽  
Archaeological Sites ◽  
Long Term Trends ◽  
The Difference

AbstractWe compare the bone assemblages of Milford 1 (TOB-3) and Golden Grove (TOB-13) in Tobago, West Indies. Milford 1 is a small preceramic occupation (ca. 3000-2800 cal B.P.), whereas Golden Grove is a large ceramic-period village (ca. 1700-900 cal B.P.). Species richness at TOB-13 is greater than at TOB-3, both in marine (67 vs. 39 fishes) and terrestrial (32 vs. 9) taxa. Major shifts in marine exploitation from the preceramic to ceramic periods can be seen in relative abundance of tuna, toadfishes, and in fishes inhabiting mangrove and brackish water environments, and decreases in relative abundance of parrotfish, carnivorous reef fishes, and sea turtles. The abundance of tuna bones at TOB-13 is uniquely high among West Indian archaeological sites. For terrestrial taxa, the difference in species richness exceeds the expected, including decreased specialization on big game (peccaries) at TOB-13, with a greater tendency to hunt reptiles, birds, and mammals of all sizes at TOB-3. Factors underlying the shifts in fishing and hunting may include different collection methods and food preferences of non-Arawakan (preceramic) vs. Arawakan (ceramic) peoples, as well as human-induced declines in populations of peccaries, sea turtles, and selected fish species. Another possible factor is site setting, with the inhabitants of TOB-13 having enhanced access to mangrove habitats.

scholarly journals Size-distributions of <i>n</i>-alkanes, PAHs and hopanes and their sources in the urban, mountain and marine atmospheres over East Asia

2009 ◽  
Vol 9 (22) ◽  
pp. 8869-8882 ◽  
Author(s):  
G. Wang ◽  
K. Kawamura ◽  
M. Xie ◽  
S. Hu ◽  
S. Gao ◽  
...  
Keyword(s):  
East Asia ◽  
Geometric Mean ◽  
Bimodal Distribution ◽  
Size Distributions ◽  
Marine Aerosols ◽  
Hygroscopic Growth ◽  
Okinawa Island ◽  
Marine Samples ◽  
Fine Mode ◽  
The Difference

Abstract. Size-segregated (9 stages) n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and hopanes in the urban (Baoji city in inland China), mountain (Mt. Tai in east coastal China) and marine (Okinawa Island, Japan) atmospheres over East Asia were studied using a GC/MS technique. Ambient concentrations of n-alkanes (1698±568 ng m−3 in winter and 487±145 ng m−3 in spring), PAHs (536±80 and 161±39 ng m−3), and hopanes (65±24 and 20±2.4 ng m−3) in the urban air are 1–2 orders of magnitude higher than those in the mountain aerosols and 2–3 orders of magnitude higher than those in the marine samples. Mass ratios of n-alkanes, PAHs and hopanes clearly demonstrate coal-burning emissions as their major source. Size distributions of fossil fuel derived n-alkane, PAHs and hopanes were found to be unimodal in most cases, peaking at 0.7–1.1 μm size. In contrast, plant wax derived n-alkanes presented a bimodal distribution with two peaks at the sizes of 0.7–1.1 μm and >4.7 μm in the summer mountain and spring marine samples. Among the three types of samples, geometric mean diameter (GMD) of the organics in fine mode (<2.1 μm) was found to be smallest (av. 0.63 μm in spring) for the urban samples and largest (1.01 μm) for the marine samples, whereas the GMD in coarse mode (≥2.1 μm) was found to be smallest (3.48 μm) for the marine aerosols and largest (4.04 μm) for the urban aerosols. The fine mode GMDs of the urban and mountain samples were larger in winter than in spring and summer. Moreover, GMDs of 3- and 4-ring PAHs were larger than those of 5- and 6-ring PAHs in the three types of atmospheres. Such differences in GMDs can be interpreted by the repartitioning of organic compounds and the coagulation and hygroscopic growth of particles during a long-range transport from the inland continent to the marine area, as well as the difference in their sources among the three regions.

scholarly journals Capacity Estimation for On-Ramp Merging Section of Urban Expressway Based on Time Headway Loss

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Xing-jian Xue ◽  
Feng Shi ◽  
Qun Chen
Keyword(s):  
Real Data ◽  
Efficient Solutions ◽  
Optimal Time ◽  
Lane Changing ◽  
Time Headway ◽  
Urban Expressway ◽  
Proposed Model ◽  
The Difference ◽  
Capacity Drop ◽  
Gap Acceptance Theory

This paper proposes a model for estimating capacity of on-ramp merging section of urban expressway based on dynamics and gap acceptance theory, considering lane-changing processes and time headway loss. Survey data were collected from on-ramp merging sections of shanghai urban expressway system and showed that capacity drop of on-ramp merging section is caused by drivers’ lane-changing which may lead to unsteady speed of vehicles and so prolonged time headway compared to the minimum time headway corresponding to the maximum capacity. Three parameters (optimal time headway, time headway loss, and interference quantity of lane-changing) are given and a methodology by accumulating time headway loss due to lane-changing is developed to estimate the capacity drop. Results’ comparisons between real data and microsimulation of on-ramp merging sections and sensitivity analysis show that the proposed model can produce reliable and accurate results. This study also reveals that ramp flow and the difference between the optimal speed and the lane-changing speed of fleet have a great impact on capacity drop. This study is beneficial to evaluate congestion levels, to understand complex traffic phenomena, and so to find efficient solutions.

Adaptive foraging tactics of greater short-nosed fruit bats on a spiny shrub and its effect on seed dispersal

2021 ◽  
Author(s):  
Dhanapal Sangavi ◽  
Chinnaperamanoor Madhappan Murugan ◽  
Valliyappan Mahandran ◽  
Ganapathy Marimuthu ◽  
Parthasarathy Thiruchenthil Nathan
Keyword(s):  
Seed Dispersal ◽  
Fruit Bats ◽  
Foraging Tactics ◽  
Adaptive Foraging
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