Capture Behavior Research Articles

Rescue and Translocation of Hispaniola Hutia (Plagiodontia aedium) in Pueblo Viejo, Cotuí Mining Concession Area.

Translocation of species is a common practice used in endangered species management and conservation plans, which can have the purpose of establishing new populations which are at risk of being wiped out, increase a species chance of survival or recovery, and to preserve genetic diversity. The present study details the rescue and relocation process of Hispaniola Hutia (Plagiodontia aedium) in the municipality of Cotuí, Dominican Republic. Data are presented for eight individuals, belonging to two different families, detailing capture methods, handling, reintroduction method, and behavior, as well as data on post-release monitoring for both families. It was found that the most efficient capture method was active capture by hand (6/8). The family groups were heterogeneous, although both families had in common the presence of a single adult male. The average weight of the individuals was 1.19 kg. Blood tests were carried out on the animals before being taken to the holding pens and compared with the values of other rodents, showing that hematic values for P. aedium were like those of another hutia species, Cynomys ludovicianus. During the period animals were held in pens before reintroduction, hutias showed trophic preferences for Clusia rosea and Guarea guidonea. The only supplementary food they consumed was Daucus carota. A fight was observed between members of different families during the acclimation period in the holding pen, between a subadult male and another dominant one, evidencing territorial behavior. Post-release monitoring of the families showed that the selection of habitat for relocation, based on the characterization of active burrows in the area, was successful in one of the two families relocated. One of the families abandoned the selected area for translocation during the monitoring. It is important to note that accurate population data of the targeted population, such as abundance and density, are necessary to guarantee the survival of the translocated animals in the new environment. The reintroduction method used in this study may serve as a baseline for future translocation projects for the species.

Capture behavior of self-propelled particles into a hexatic ordering obstacle

Abstract Computer simulations are utilized to investigate the dynamic behavior of self-propelled particles (SPPs) within a complex obstacle environment. The findings reveal that SPPs exhibit three distinct aggregation states within the obstacle, each contingent on specific conditions. A phase diagram outlining the aggregation states concerning self-propulsion conditions is presented. The results illustrate a transition of SPPs from a dispersion state to a transition state as persistence time increases within the obstacle. Conversely, as the driving strength increases, self-propelled particles shift towards a cluster state. A systematic exploration of the interplay between driving strength, persistence time, and matching degree on the dynamic behavior of self-propelled particles is conducted. Furthermore, an analysis is performed on the spatial distribution of SPPs along the y-axis, capture rate, maximum capture probability, and mean-square displacement. The insights gained from this research serve as valuable contributions to understanding the capture and collection of active particles.

Visible Light-Responsive Crystalline B←N Host Adducts with Solvent-Induced Allosteric Effect for Guest Release.

Photo-responsive organic crystals, capable of converting light energy into chemical energy to initiate conformational transitions, present an emerging strategy for developing lightweight and versatile smart materials. However, visible light-triggered tailored guests capture and release behaviors in all-organic solids are rarely reported. Here, we introduce a photoreactive crystalline boron-nitrogen (B←N) host adduct with the ability to undergo [2+2] photocycloaddition upon 447 nm light exposure. This process facilitates single-crystal-to-single-crystal (SCSC) photodimerization in the mother liquor, maintaining the original B←N host structure. Weakened intermolecular interactions within the photodimer host contribute to fast guest release in air under irradiation. Furthermore, the dynamic B←N bonds enable reversible transformations between organic host adducts and adduct cocrystals under the solvent-induced allosteric effect. As a result, four B←N host adduct crystals containing individual alkane guest are easily obtained and exhibited the ability of photo-controlled alkane release. Therefore, the integration of photo reactivity and structural transformation within B←N host adduct enables customized capture and release of guest molecules.

Visible Light‐Responsive Crystalline B←N Host Adducts with Solvent‐Induced Allosteric Effect for Guest Release

AbstractPhoto‐responsive organic crystals, capable of converting light energy into chemical energy to initiate conformational transitions, present an emerging strategy for developing lightweight and versatile smart materials. However, visible light‐triggered tailored guests capture and release behaviors in all‐organic solids are rarely reported. Here, we introduce a photoreactive crystalline boron‐nitrogen (B←N) host adduct with the ability to undergo [2+2] photocycloaddition upon 447 nm light exposure. This process facilitates single‐crystal‐to‐single‐crystal (SCSC) photodimerization in the mother liquor, maintaining the original B←N host structure. Weakened intermolecular interactions within the photodimer host contribute to fast guest release in air under irradiation. Furthermore, the dynamic B←N bonds enable reversible transformations between organic host adducts and adduct cocrystals under the solvent‐induced allosteric effect. As a result, four B←N host adduct crystals containing individual alkane guest are easily obtained and exhibited the ability of photo‐controlled alkane release. Therefore, the integration of photo reactivity and structural transformation within B←N host adduct enables customized capture and release of guest molecules.

Fluorescence visualization dynamics of carbonated water injection processes in homogeneous glass micromodels

Understanding the flow behavior of oil–water phases in porous media is crucial for revealing the kinetic mechanisms underlying oil–water movement. In this study, we designed and constructed a fluorescence visualization experimental platform for carbonated water injection (CWI). We evaluated the effects of nine distinct injection rates on oil production and CO2 sequestration capabilities using three types of homogeneous porous structure micromodels. The microscale oil–water seepage behavior at the pore scale was also explored. The experimental results indicate that optimally increasing the injection rate can improve displacement efficiency, whereas excessively high rates may lead to viscous and capillary fingering. The geometry of the micromodels, particularly the hexagonal matrix, demonstrates potential advantages in enhancing oil displacement due to its uniform flow paths. The capillary number (Ca) significantly influences oil droplet capture behavior within micromodels. For instance, micromodel A captures the largest ganglion area at low Ca values, with a noticeable reduction in average ganglion area as Ca increases. Conversely, micromodels B and C exhibit similar trends in ganglion size variation at high Ca values, suggesting a more uniform impact of pore structure on oil droplet capture behavior. At elevated Ca values, capillary forces exert a more uniform and controlled effect on oil droplet capture and release, minimizing size variability. Additionally, the injection rate plays a critical role in CO2 sequestration, with higher rates promoting convective mixing between CO2 and reservoir fluids, thereby enhancing dissolution and storage efficiency. The complexity of the pore structure, characterized by the presence of micropores and macropores, affects the dissolution kinetics and mobility of CO2, influencing sequestration efficiency. These experimental findings provide valuable insights into the dynamics of oil–water motion and the potential for enhanced oil recovery (EOR) and CO2 storage, offering essential guidance for optimizing CWI strategies in the petroleum industry.

Structural Diversity and Dimensionality of Three Cu(II)-dpds-C5O5 2- Coordination Polymers Controlled by the Coordination Sphere of Cu(II) Centers and the Coordination Modes of C5O5 2- (dpds = 4,4'-Dipyridyldisulfide).

Three supramolecular architectures, [Cu2(dpds)2(C5O5)2(H2O)4]·3H2O (1), [Cu(dpds)(C5O5)]·3H2O (2), and [Cu2(dpds)2(C5O5)2]·9H2O·C2H5OH (3) (dpds = 4,4'-dipyridyldisulfide and C5O5 2- (croconate) = dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione), have been synthesized and structurally characterized. Compound 1 contains two crystallographically independent Cu(II) ions, which are both distorted octahedral geometry with elongation along the croconate- and H2O-bound axial positions and bonded with two N atoms of two dpds, two O atoms of one C5O5 2-, and two H2O molecules. Two crystallographically independent dpds ligands, both adopting the bis-monodentate bridging mode, connect two Cu(II) ions to form a one-dimensional zigzag chain-like coordination polymer. In 2 and 3, there are two and three crystallographically independent Cu(II) ions, respectively, which are all distorted octahedral geometries with elongation along the croconate-bound axial positions six-coordinated and bonded with two N atoms of two dpds ligands in cis- or/and trans-forms and four O atoms of two C5O5 2- ligands. The dpds ligands in 2 and 3 all adopt the bis-monodentate bridging mode, and the C5O5 2- ligands act as bridging ligands with bridging bis-bidentate through three C5O5 2- oxygen atoms in 2 and bridging bis-bidentate through four adjacent C5O5 2- oxygen atoms in 3, respectively, linking the Cu(II) ions to generate a two-dimensional layered and a three-dimensional metal-organic framework, respectively. The structural diversity and dimensionality observed in 1-3 may be attributed to the cis- or/and trans-coordination sphere of Cu(II) centers with two dpds ligands and the coordination modes of croconate ligands. Thermal stability and in situ temperature-dependent structural variations of 1-3 have been verified by thermogravimetric analysis and powder X-ray diffraction measurements. Compounds 1 and 3 both exhibit water vapor capture behaviors with hysteresis isotherms.

Evidence for a by‐product mutualism in a group hunter depends on prey movement state

Abstract Group‐hunting animals have been shown to engage their prey in long pursuits (kms) to increase capture success, but the evidence for this is limited to a few terrestrial species. This predation strategy may be effective in the open‐ocean, where group‐hunts are characterised by large predator–prey size ratios and there are few places for prey to hide. However, recording the attack rates, capture rates and capture success probabilities of grouping predators during long‐distance pursuits through the open ocean, remains a significant challenge. Here we use a combination of underwater and aerial video to assess the attack and capture behaviour of striped marlin, Kajikia audax, in relation to the movement of their schooling prey (‘stationary’ and ‘mobile’ movement states) during group hunts. We found that the attack rate was higher when the prey school was ‘stationary’ and, during these times, individual marlin could make longer sequences of uninterrupted attacks on the prey school, effectively monopolising the prey resource for short periods over conspecifics. When the prey school was ‘mobile’, the attack pattern changed and individual marlin alternated their attacks on the prey school more frequently. Capture success probability (likelihood of capture per attack) was not affected by prey movement state. However, attacks on ‘mobile’ schools resulted in more prey fish becoming isolated from the school, and these isolated prey were easily captured—not by the attacker but by conspecifics swimming nearby. The likelihood of a prey becoming isolated from a ‘mobile’ school was predicted by prey school speed, with a 0.1 m s−1 increase leading to an 18.01% increase in the chance of isolation. Altogether this meant the capture rate at the group level was highest when the prey school was ‘mobile’ rather than ‘stationary’ because the predators that were pursuing the ‘mobile’ prey school had an increased availability of isolated and easy to capture prey. This mechanism provides evidence for a by‐product mutualism selecting for conspecific group formation and we discuss our findings in consideration of the social structure of the hunting group and the type of prey. Read the free Plain Language Summary for this article on the Journal blog.

Utilizing Limestone Alone for Integrated CO2 Capture and Reverse Water-Gas Reaction in a Fixed Bed Reactor: Employing Mass and Gas Signal Analysis

The integrated CO2 capture and utilization coupled with the reverse water-gas shift reaction (ICCU-RWGS) presents an alternative pathway for converting captured CO2 into CO in situ. This study investigates the effectiveness of three calcium-based materials (natural limestone, sol-gel CaCO3, and commercial CaCO3) as dual-functional materials (DFMs) for the ICCU-RWGS process at intermediate temperatures (650–750 °C). Our approach involves a fixed-bed reactor coupled with mass spectrometry and in situ Fourier transform infrared (FTIR) measurements to examine cyclic CO2 capture behavior, detailed physical and chemical properties, and morphology. The in situ FTIR results revealed the dominance of the RWGS route and exhibited self-catalytic activity across all calcium-based materials. Particularly, the natural limestone demonstrated a CO yield of 12.7 mmol g−1 with 100% CO selectivity and 81% CO2 conversion. Over the 20th cycle, a decrease in CO2 capture capacity was observed: sol-gel CaCO3, natural limestone, and commercial CaCO3 showed reductions of 44%, 61%, and 59%, respectively. This suggests inevitable deactivation during cyclic reactions in the ICCU-RWGS process, while the skeleton structure effectively prevents agglomeration in Ca-based materials, particularly in sol-gel CaCO3. These insights, coupled with the cost-effectiveness of CaO-alone DFMs, offer promising avenues for efficient and economically viable ICCU-RWGS processes.

An Empirical Study on the Judicial Regulation of Unfair Competition in Data Scraping Behavior

Currently, China's data-related legislation is still in the initial stage of gradual exploration. Due to the unfair competition disputes involving data capture with a variety of data types, complex technical means, capture behavior hidden and other characteristics, resulting in the judge in the trial of data capture cases mostly choose to apply the general provisions of the “Anti-Unfair Competition Law”, that is, the second article to be adjudicated, which makes the data capture behavior of the cases arising from the dispute is more and more, the data capture behavior whether it constitutes unfair competition, This has led to an increasing number of cases and disputes arising from data-scraping behavior. Therefore, this paper takes the data capture behavior as the research object, takes some typical cases as examples, discusses the adjudication results and thoughts of the cases, and in the process, finds that in the judicial practice of such dispute cases, there exists the difference of the applicable law, the judgment standard of the legitimacy of the data capture behavior is not clear, and the understanding of the damages caused by the unfair competition behavior of the data capture is not the same, and other problems. In view of this, in judicial practice, Article 2 and Article 12 should be clearly applied, and importance should be attached to the criteria for judging the legitimacy of data capture; finally, through the theory of balance of interests and the principle of proportionality, the interests of data platforms, consumer interests and public interests of the society involved in data capture should be taken into consideration, thus realizing the balance of interests of multiple parties, and achieving the balance between data protection and data flow through dynamic justice.

Mutations in the albinism gene oca2 alter vision-dependent prey capture behavior in the Mexican tetra.

Understanding the phenotypic consequences of naturally occurring genetic changes, as well as their impact on fitness, is fundamental to understanding how organisms adapt to an environment. This is critical when genetic variants have pleiotropic effects, as determining how each phenotype impacted by a gene contributes to fitness is essential to understand how and why traits have evolved. A striking example of a pleiotropic gene contributing to trait evolution is the oca2 gene, coding mutations in which underlie albinism and reductions of sleep in the blind Mexican cavefish, Astyanax mexicanus. Here, we characterize the effects of mutations in the oca2 gene on larval prey capture. We find that when conspecific surface fish with engineered mutations in the oca2 allele are hunting, they use cave-like, wide angle strikes to capture prey. However, unlike cavefish or surface fish in the dark, which rely on lateral line mediated hunting, oca2 mutant surface fish use vision when striking at prey from wide angles. Finally, we find that while oca2 mutant surface fish do not outcompete pigmented surface siblings in the dark, pigmented fish outcompete albino fish in the light. This raises the possibility that albinism is detrimental to larval feeding in a surface-like lighted environment, but does not have negative consequences for fish in cave-like, dark environments. Together, these results demonstrate that oca2 plays a role in larval feeding behavior in A. mexicanus. Further, they expand our understanding of the pleiotropic phenotypic consequences of oca2 in cavefish evolution.

Biomass betulin-based porous aromatic frameworks nanomicrospheres as adsorbents for reversible capture of iodine

Betulin with a modifiable hydroxyl group and a rigid backbone is a kind of natural triterpene product that extracted from white barked birch bark with up to 30 % of its dry weight. Herin, we prepared a series of betulin-based porous aromatic frameworks (BEPAFs) nanomicrospheres by [Rh(nbd)Cl]2 polymerization or Sonogashira-Hagihara coupling reaction for iodine vapor capture and adsorption. The resulting BEPAFs nanomicrospheres presented perfect thermal stability and high specific surface areas that up to 324.6 m2 g−1, 506.3 m2 g−1 and 320.5 m2 g−1 for BEPAF-1, BEPAF-2 and BEPAF-3, respectively. Based on the above characteristics, the BEPFAs nanomicrospheres showed an excellent iodine capture performance with the volatile iodine capture ability reached 3.79 g g−1 and iodine adsorption in cyclohexane solution up to 389.9 mg g−1. The iodine capture behavior is consistent with the pseudo-second-order model, indicating that the iodine adsorption process of BEPAFs microspheres belongs to multilayer heterogeneous surface chemical adsorption. Furthermore, the BEPFAs nanomicrospheres could maintained 88.26 % of the absorption capacity after four cycles that endow them a great potential in practical application. This research provides a facile synthesis of biomass porous aromatic framework nanomicrospheres adsorbents based on the natural product.

Cavefish dorsoventral axis angle during wall swimming: laterality asymmetry

The Astyanax fish exhibits two morphs: an eyed, pigmented surface morph and an eyeless, depigmented cave morph. Previous studies have shown that blind morphs swim nearly parallel to the wall and can sense detailed information about objects by gliding alongside them and sensing changes in the flow field around their body using their lateral line sensory system. Hence, cavefish can build hydrodynamic images of their surroundings. Field observations showed that one of their presumptive prey, mysid shrimp, is predominately found not on the floor, but crawling on the walls. In our study, the angle of the body axis with respect to a vertical wall was measured while fish swam in a tank. Results show that when swimming by a wall, cavefish incline the vertical axis of their body away from the wall. But most significantly, this angle is different when the right side or the left side of their body is oriented towards the wall. Intriguingly, cavefish have a leftward-biased dorso-cranial bend, where the convex side of the head is towards their right side. Other studies have shown behavioral “handedness”. When exhibiting Vibration Attraction Behavior (VAB), cavefish in the field show laterality on the preponderant side they circle to explore a vibrating stimulus. Likewise in larval prey capture (LPC) behavior, larvae strike towards prey preferentially located on one side. Our results support that cavefish also express behavioral lateralization during passive swimming by walls and/or when searching for food that is perched on the walls, such as mysid shrimp.

Initial load factor adjustment through genetic algorithm for the generalized displacement control method: Implementation on non-rigid origami analysis

The nonlinear analysis of structural systems relies on effective nonlinear solution schemes, known as nonlinear solvers or path-following methods. This paper explores the challenge of determining the initial load factor in such analyses, with a particular focus on complex origami structures. This study presents a novel approach that leverages genetic algorithms (GA) to efficiently determine the initial load factor for the generalized displacement method. Building upon the concept of stiffness parameters, our method offers a systematic solution. In this work, GA serves as a tool to discover the appropriate initial load factor based on changes in the stiffness parameter, providing a more rational and user-friendly approach. To demonstrate the practical applicability of our approach, we apply it to a range of complex origami problems, including the folding of Miura-ori, folding of an egg-box origami, bending of an egg-box origami, and folding of an arc Miura-ori. These examples, along with a truss example, encompass highly nonlinear behaviors, including limit points, extreme stiffness fluctuations, snap-through, and snap-back. Our results showcase the effectiveness of our method in accurately tuning the initial load factor to capture and track intricate nonlinear behaviors. Furthermore, it offers the flexibility to fine-tune the distribution of points along the path and manage the resolution of the depicted equilibrium path. This versatility underscores its potential applications in fields such as deployable structures and complex large deformation structural analysis.

Impact of pH, ionic strength, and operating conditions on capture mechanisms in nanoparticle filtration

Filtration of biopharmaceutical streams can be complex due to the variety of components in the stream and their interactions among themselves and with the filter pore surfaces. This work used a variety of measurements to study the filtration of model silica nanoparticles through asymmetric hydrophilized polyethersulfone (mPES) membrane in solutions covering a range of pH and ionic strengths. Measurements included particle size, particle concentration, zeta potential, particle-particle and particle-membrane surface intermolecular forces. These measurements were used to rationalize observed particle capture behavior under various filtration conditions. We found that increasing ionic strength and decreasing pH resulted in higher particle aggregation and higher particle retention due to adsorption of model silica nanoparticles to the membrane and sieving of aggregates within the membrane. In addition, captured particles can be eluted from the membrane in some cases, depending on the operating conditions, extent of particle loading, buffer flush pressure, and buffer pH and conductivity conditions. These findings provide insight into methods to improve filtration performance and particle capture or release, including product recovery, in filtration processes.

Carbon capture in polymer-based electrolytes.

Nanoparticle organic hybrid materials (NOHMs) have been proposed as excellent electrolytes for combined CO2 capture and electrochemical conversion due to their conductive nature and chemical tunability. However, CO2 capture behavior and transport properties of these electrolytes after CO2 capture have not yet been studied. Here, we use a variety of nuclear magnetic resonance (NMR) techniques to explore the carbon speciation and transport properties of branched polyethylenimine (PEI) and PEI-grafted silica nanoparticles (denoted as NOHM-I-PEI) after CO2 capture. Quantitative 13C NMR spectra collected at variable temperatures reveal that absorbed CO2 exists as carbamates (RHNCOO- or RR'NCOO-) and carbonate/bicarbonate (CO32-/HCO3-). The transport properties of PEI and NOHM-I-PEI studied using 1H pulsed-field-gradient NMR, combined with molecular dynamics simulations, demonstrate that coulombic interactions between negatively and positively charged chains dominate in PEI, while the self-diffusion in NOHM-I-PEI is dominated by silica nanoparticles. These results provide strategies for selecting adsorbed forms of carbon for electrochemical reduction.

Selective CO2 Capture from CO2/N2 Gas Mixtures Utilizing Tetrabutylammonium Fluoride Hydrates.

Gas hydrates, a type of inclusion compound capable of trapping gas molecules within a lattice structure composed of water molecules, are gaining attention as an environmentally benign gas storage or separation platform. In general, the formation of gas hydrates from water requires high-pressure and low-temperature conditions, resulting in significant energy consumption. In this study, tetrabutylammonium fluoride (TBAF) was utilized as a thermodynamic promoter forming a semi-clathrate-type hydrate, enabling gas capture or separation at room temperature. Those TBAF hydrate systems were explored to check their capability of CO2 separation from flue gas, the mixture of CO2 and N2 gases. The formation rates and gas storage capacities of TBAF hydrates were systematically investigated under various concentrations of CO2, and they presented selective CO2 capture behavior during the hydrate formation process. The maximum gas storage capacities were achieved at 2.36 and 2.38 mmol/mol for TBAF·29.7 H2O and TBAF·32.8 H2O hydrate, respectively, after the complete enclathration of the feed gas of CO2 (80%) + N2 (20%). This study provides sufficient data to support the feasibility of TBAF hydrate systems to be applied to CO2 separation from CO2/N2 gas mixtures based on their CO2 selectivity.

LDH/MXene Synergistic Carrier Separation Effects to Improve the Photoelectric Catalytic Activities of Bi2WO6 Nanosheet Arrays.

Photoelectric catalysis is a green and efficient way to degrade pollutants, which has been paid more and more attention by researchers. Among them, Bi2WO3 has been proved to have excellent photocatalytic oxidation activity on its {001} facets. In this study, {001}-oriented facets with high exposure were successfully integrated into Bi2WO6 nanoplate arrays (Bi2WO6 NAs) to create a photoelectrode. This structure was grown in situ on an indium tin oxide (ITO) substrate. To promote photogenerated carrier separation efficiency and reduce agglomeration of Bi2WO6 photocatalysts, the electrochemical deposition of NiFe-layered double hydroxide (NiFe-LDH) and Ti3C2 (MXene) were introduced in this research to synergistically catalyze pollutant degradation. Morphology, spectral characterization, and electrochemical analysis jointly confirmed that the outstanding performance of hole capture behavior with LDH and electron conduction properties with MXene were the main reasons for the improvement in catalytic activity of the photoelectrode. Taking bisphenol A (BPA) as the model pollutant, the rate constant k of the NiFe-LDH/Ti3C2/Bi2WO6 NAs photoelectrode reaches 0.00196 min-1 under photoelectrocatalytic (PEC) conditions, which is 4.5 times that of the pure Bi2WO6 NAs photoelectrode. This work provides a new way to improve the reaction kinetics of the PEC degradation of pollutants.

Carbon dioxide adsorption capacity of porous carbon after polyamine impregnation under different pore structures and temperatures

Composites of polyethyleneimine (PEI) and porous carbon (PC) are effective and reversible CO2 adsorbents. Within these composite materials, the morphologies of PEI in different pore structures significantly influence CO2 capture behaviors, yet little is known about the movement of PEI molecules in PC. In this work, the CO2 adsorption capacity of PEI loaded on PC with different pore structures was investigated. The result shows that the average pore size of 3.63 nm loaded PEI has the maximum CO2 adsorption capacity at 50 ℃. Based on it, we establish a model that the loading of PEI in different pore size PCs for the first time and explain the morphology of PEI in the pore channel. This model displayed the changes in PEI chains and PEI agglomerated cores at different temperatures and pore sizes. In particular, the uptake amount of CO2 in PEI is attributed to the number of amine sites accessible. The PEI agglomerated core formed in smaller pore sizes is smaller and is more susceptible to temperature, thus the PEI agglomerated core exposes more amine sites for CO2 adsorption with increasing temperature. As the PC pore size increases, the PEI agglomerate core also enlarges, leading to greater spatial resistance and therefore exposing fewer amine-based sites when the temperature increases. The investigation of PEI/PC structure–property correlations and adsorption properties provides unique insights that could inform the rational design of better adsorbents.

Spotted hyena (Crocuta crocuta) predation on passerine birds in Namibia

Spotted hyenas (Crocuta crocuta) are known for their flexible foraging behavior and trophic interactions with diverse prey species. However, most studies describing their hunting behavior are focused on predation of large prey. Here we describe the capture rates and behavior of adult and subadult spotted hyenas hunting passerine birds. Hyenas were actively chasing, catching and feeding on red-billed queleas (Quelea quelea), a passerine bird gathering in large flocks at a waterhole in the Etosha National Park, Namibia. In total, we observed 38 successful captures with the average individual capture rate of 21 birds caught per hour. It remains unclear if this is a learned behavior of a single hyena clan or if it could be a widespread interaction across Africa, where the two species co-occur. Although it is unlikely that passerines could make up a substantial part of a spotted hyenas diet regardless of the location, our observations provide a rare documented example of trophic interactions between a large carnivore and small birds. It also represents an addition to a diverse repertoire of hyena foraging behaviors, which confirms their adaptability in obtaining food from non-typical sources.

How Urban-Tolerant Are They? Testing Prey–Capture Behavior of Introduced Jorō Spiders (Trichonephila clavata) Next to Busy Roads

An invasive orb-weaving spider from east Asia is now spreading through the southeastern United States; Trichonephila clavata (the “jorō spider”) makes large, imposing webs seemingly everywhere, including in urban landscapes, and even next to busy roads. However, areas near roads come with frequent disturbances, including auditory and vibrational, which for many animals, leads to physiological or behavioral changes. Here we tested if varying levels of road traffic affect the prey–capture behavior of jorō spiders in northeast Georgia. We visited roadsides that ranged in traffic density and exposed nearby jorō spiders to a simulated prey (a tuning fork at 128 hz frequency, touched to the web), and recorded whether or not the spider attacked it. Out of 357 total trials across 20 different roads, jorō spiders attacked the simulated prey 59% of the time, but at the local scale, there was high variability in this rate; at some roadsides, over 80% of the spiders attacked, while at others, less than 30% did. When all roads were considered collectively, there was a small but significant (negative) correlation between daily road traffic and spider attack rates. Put another way, spiders near moderate- to heavy-traffic roads were slightly less likely to attack than those near low-traffic roads (51% vs. 65%). Jorō spiders appear to be able to live near roads, but this does come with a cost in terms of prey capture. However, spiders near busier roads did not weigh less than those in other sites, suggesting they may be able to compensate for the disturbance. These findings add to the accumulating evidence around this species that points to its ability to exist in human-dominated landscapes, which will likely aid its spread in the introduced range.