Variation of parental and chick diet in opportunistic insectivorous European Bee-eaters

Insectivorous Palaearctic bird species associated with open habitats rely on high prey abundances,which are currently declining due to habitat loss and intensive agricultural practices.The European Bee-eater(Merops apiaster)is an opportunistic insectivore of open habitats,preying mainly on medium to large-sized flying insects.Its diet composition received some attention in the past,but the current variation in diet composition of birds breeding across different habitats,and between adults and chicks remains poorly known.In this study,we determine variation in bee-eaters’diet in colonies located in five common habitats at the Iberian Peninsula.We also assess differences in the diet composition of chicks and adults and investigate seasonal diet selectivity of adults.Finally,we explore the variability in the size of prey provided to chicks throughout their growth period.Hymenoptera and Coleoptera were the most important groups for bee-eaters,with adults and chicks consuming 58.8%and 64.1%of hymenopterans and 37.6%and 28.6%of coleopterans,respectively.The proportion of Hymenoptera(42.3–55.7%)and Coleoptera(43.3–53.5%)in the diet was similar in colonies in pasture and oak habitats,but Hymenoptera dominated(83.8%and 95.7%)in meadow and mixed forest colonies.Despite being a generally opportunistic predator,adult bee-eaters provide their progeny with an increasing proportion of larger insects through chick development.Moreover,they equally take Hymenoptera and Coleoptera for themselves and their chicks,even when the abundance of these insects decreases seasonally.Overall,these results suggest that local prey availability associated with specific habitats influences diet composition and that regional declines in certain groups may,therefore,affect insectivore species differently according to their dietary and habitat preferences.

Influence of prey availability on the movement pattern of breeding saker falcons(Falco cherrug)in Mongolia

As an apex predator in arid steppe,saker falcon plays a crucial role in maintaining ecosystem balance.Understanding their movement patterns concerning conspecific competition and prey availability is important for their conservation.We aim to understand how movement pattern of breeding saker falcons relates to prey availability.Twelve adult sakers were tracked during the breeding seasons,using satellite transmitters.Throughout the breeding season,sakers exhibited territorial behavior,with minimal overlap in range use among neighboring conspecifics.Males occupied larger areas(mean=2,397 ha,median=1,221 ha),compared to females(mean=1,241 ha,median=554 ha),and it remained consistent throughout breeding season.Female home range size increased notably during a late nestling stage and post-fledging dependence periods,indicating release from brooding constraints.Notably,we found a negative relationship between male home range size and prey availability.In high rodent density areas,males occupied smaller areas(mean=1,135 ha,median=1,034 ha),contrasting with low rodent density areas(mean=6,815 ha,median=6,516 ha).However,no significant relationship was observed between female home range size and prey availability.We also noted instances of nest abandonment and early dispersal behavior in some females,potentially influenced by a handicapping effect of tagging.Our findings offer valuable insight into how prey availability shapes saker falcon space use and defines their spatial requirements for successful breeding.This knowledge is crucial for the conservation and management of globally endangered saker falcons,informing targeted habitat protection and resource management strategies.

Experimental clearance rate and intraguild predation of jellyfish Cyanea nozakii

Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.nozakii medusae on different prey items.Research is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by C.nozakii.To address the knowledge gaps,the clearance rates of C.nozakii for different prey items,including copepods(small<1000μm and large>1000μm),fish larvae,and gelatinous prey(hydromedusae,A.coerulea ephyrae,and chaetognaths),were measured.The influence of predator size on the clearance rate was also determined.Additionally,we examined the intraguild predation of C.nozakii on A.coerulea medusae.The clearance rates of C.nozakii varied widely with prey organisms,being independent of prey concentrations.Gelatinous organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by C.nozakii.The clearance rate increased linearly with the cross-sectional area of C.nozakii.Body size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny.C.nozakii preyed voraciously on A.coerulea in high feeding efficiency,but the clearance rate decreased with increasing A.coerulea(as prey)size.This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A.coerulea by C.nozakii.The information regarding the feeding ecology of C.nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.

Dynamical Behaviors of a Modified Leslie-Gower Predator-Prey System with Fear Effect and Prey Refuge

In this paper, the dynamical behaviors of a modified Leslie-Gower predator-prey model incorporating fear effect and prey refuge are investigated. We delve into the construction of the model and its biological significance, with preliminary results encompassing positivity, boundedness, and persistence. The stability of the system’s boundary and positive equilibrium points is proven by calculating the real part of the eigenvalues of the Jacobian matrix. At the positive equilibrium point, we demonstrate that the system’s unique positive equilibrium is globally asymptotically stable by using the Dulac criterion. Furthermore, at this equilibrium point, we employ the Implicit Function Theorem to discuss how fear effects and prey refuges influence the population densities of both prey and predators. Finally, numerical simulations are conducted to validate the above-mentioned conclusions and explored the impact of Predator-taxis sensitivity αon dynamics of the system.

一类食饵具有阶段结构的时滞Predator-Prey系统的周期解(英文)

研究了一类时滞Predator-Prey系统,其中Prey种群是具有两个生命阶段的种群,即幼年阶段和成年阶段。Predator种群只能捕食Prey幼年种群。通过应用Gaines和Mawhin重合度理论的连续函数定理,给出了系统正周期解存在的充分条件。

Trace Elements in Mollusks, Crustaceans and Fish Commonly Consumed by the Catfish <i>Chrysichthys nigrodigitatus</i>Lacépède, 1803 from the Lake Togo-Lagoon of Aného Hydrosystem (Southern Togo)

The omnivorous fish species, C. nigrodigitatus feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of C. nigrodigitatus. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in P. fusca. The most contaminated species by trace elements were benthic organisms: M. perna (Cd, Pb, Hg), Pagurus sp. (Cr, Ni, Cu, Zn), G. paradoxa (As) and P. fusca (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in M. perna and G. paradoxa. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in M. perna. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.

Prey preference of the common long-armed octopus Octopus minor(Cephalopoda: Octopodidae) on three different species of bivalves

Octopus minor is widely distributed along the northern coast of China. To date, there is little information on the prey selection process of this species. To understand this process, several experiments were carried out. Three types of bivalves, namely, Ruditapes philippinarum , Mactra chinensis , and Mytilus galloprovincialis , were used to observe the prey selection of O . minor and to analyze the potential causes of prey selection from three aspects: prey profi tability, adductor muscle tension and handling time. Under single-prey conditions, we found that the average (±SD) predation rates of O . minor on R . philippinarum , M . chinensis , and M . galloprovincialis were 1.73±0.50, 1.27±0.42, and 0.8±0.2/d, respectively. Under diff erent prey combinations, octopods actively selected one type of prey over the other(s), and the order of prey preference was R . philippinarum , followed by M . chinensis and lastly M. galloprovincialis . Furthermore, the shells of the consumed prey showed that O . minor only consumed bivalves by pulling them apart since there was no evidence of drill holes on the shells. The prey selection of O . minor was related to the prey profi tability and handling time;O . minor appeared to select preys with a higher profi tability and a shorter handling time. However, the diffi culty in opening the bivalve was not consistent with the prey preference of the octopods. These results suggest that O . minor prefers to consume R . philippinarum possibly due to a high profi tability and a short handling time that supports the optimum Foraging Theory.

A combined airfoil with secondary feather inspired by the golden eagle and its influences on the aerodynamics

Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To reveal the flying abilities, avian geometry of a golden eagle was extracted based on noncontact surface measurements using a ROMBER three-dimensional laser scanner. Distributions of a camber line, thickness and a secondary feather line of the extracted point cloud were fitted using convenient analytical expressions. A traditional airfoil was established with the camber line and thickness, then a combined airfoil was constructed by combining the traditional airfoil with a secondary feather. Oscillations of an airfoil as well as rapid pitch up were simplified as a sine wave around the quarter chord axis. Thereafter, both steady and unsteady aerodynamic performances of the airfoil are computed, the influences of the secondary feather on the steady and unsteady aerodynamics were further studied.

NONLINEAR SINGULARLY PERTURBED PREDATOR-PREY REACTION DIFFUSION SYSTEMS

A class of nonlinear predator prey reaction diffusion systems for singularly pe rturbed problems are considered.Under suitable conditions, by using theory of di fferential inequalities the existence and asymptotic behavior of solution for in itial boundary value problems are studied.

Univector field method-based multi-agent navigation for pursuit problem in obstacle environments

The pursuit problem is a well-known problem in computer science. In this problem, a group of predator agents attempt to capture a prey agent in an environment with various obstacle types, partial observation, and an infinite grid-world. Predator agents are applied algorithms that use the univector field method to reach the prey agent, strategies for avoiding obstacles and strategies for cooperation between predator agents. Obstacle avoidance strategies are generalized and presented through strategies called hitting and following boundary(HFB); trapped and following shortest path(TFSP); and predicted and following shortest path(PFSP). In terms of cooperation, cooperation strategies are employed to more quickly reach and capture the prey agent. Experimental results are shown to illustrate the efficiency of the method in the pursuit problem.

Integrated search technique for parameter determination of SVM for speech recognition

Support vector machine(SVM)has a good application prospect for speech recognition problems;still optimum parameter selection is a vital issue for it.To improve the learning ability of SVM,a method for searching the optimal parameters based on integration of predator prey optimization(PPO)and Hooke-Jeeves method has been proposed.In PPO technique,population consists of prey and predator particles.The prey particles search the optimum solution and predator always attacks the global best prey particle.The solution obtained by PPO is further improved by applying Hooke-Jeeves method.Proposed method is applied to recognize isolated words in a Hindi speech database and also to recognize words in a benchmark database TI-20 in clean and noisy environment.A recognition rate of 81.5%for Hindi database and 92.2%for TI-20 database has been achieved using proposed technique.

Sexual Dimorphism of Head Size in Phrynocephalus przewalskii: Testing the Food Niche Divergence Hypothesis

Sexual size dimorphism （SSD） is a general phenomenon in lizards, and can evolve through sexual selection or natural selection. But natural selection, which was thought to operate mainly through reducing the competition be- tween the two sexes （niche divergence hypothesis）, gave rise to a lot of controversy. We tested the niche divergence hypothesis in the toad-headed lizard Phrynocephalus przewalskii by comparing diet composition and prey sizes between males and females. The species was found to be sexual dimorphic, with males having relatively larger snout-vent length, head width, head length, and tail length, while females have relatively larger abdomen length. Based on analysis of 93 studied stomachs, a total of 1359 prey items were identified. The most common prey items were formicid, lygaeid and tenebrionid. The two sexes did not differ in the relative proportions of prey size categories they consumed and the dietary overlap based on prey species was high （O = 0.989）. In addition, the meal size, the volume or any maximal dimension of the largest prey item in the stomach was not explained by the sexes. According to our results, food niche divergence might not play an important role in the SSD evolution ofP. przewalskii.

Hunter Prey Optimization with Hybrid Deep Learning for Fake News Detection on Arabic Corpus

Nowadays,the usage of socialmedia platforms is rapidly increasing,and rumours or false information are also rising,especially among Arab nations.This false information is harmful to society and individuals.Blocking and detecting the spread of fake news in Arabic becomes critical.Several artificial intelligence(AI)methods,including contemporary transformer techniques,BERT,were used to detect fake news.Thus,fake news in Arabic is identified by utilizing AI approaches.This article develops a new hunterprey optimization with hybrid deep learning-based fake news detection(HPOHDL-FND)model on the Arabic corpus.The HPOHDL-FND technique undergoes extensive data pre-processing steps to transform the input data into a useful format.Besides,the HPOHDL-FND technique utilizes long-term memory with a recurrent neural network(LSTM-RNN)model for fake news detection and classification.Finally,hunter prey optimization(HPO)algorithm is exploited for optimal modification of the hyperparameters related to the LSTM-RNN model.The performance validation of the HPOHDL-FND technique is tested using two Arabic datasets.The outcomes exemplified better performance over the other existing techniques with maximum accuracy of 96.57%and 93.53%on Covid19Fakes and satirical datasets,respectively.

Food Habits of the Grassland Wolf in Inner Mongolia of China

In this paper, food habits of the wolf (Canis lupus) was determined in Inner Monolia, using scat analysis. Results indicated that ungulates were the staple food items(frequency 53.8%, relative biomass 85.2%). In the scats, animals was 40.3% by the frequency of occurrence, and 75.7% by the relative biomass. Compared with the food habits of wolves in Heilongjiang Province, wolves showed a different pattern in prey selection in this ergion. In this study, we estimated the relative biomass of food items, and amount of each prey ingested by a wolf, based on a linear regression equation, y=2.76+0.02x(r=0.997), which was obtained in the feeding trials, It is suggerted that wolves are opportunistic predator. Some suggestions for wolf conservation and management were disussed.

Shape reconstructions and morphing kinematics of an eagle during perching manoeuvres

The key to high manoeuvre ability in bird flight lies in the combined morphing of wings and tail.The perching of a wild Haliaeetus Albicilla without running or wing flapping is recorded and investigated using a high-speed digital video.A shape reconstruction method is proposed to describe wing contours and tail contours during perching.The avian airfoil geometries of the Aquila Chrysaetos are extracted from noncontact surface measurements using a ROMBER 3D laser scanner.The wing planform,chord distribution and twist distribution are fitted in convenient analytical expressions to obtain a 3D wing geometry.A three-jointed arm model is proposed to associate with the 3D wing geometry,while a one-joint arm model is proposed to describe the kinematics of tail.Therefore,a 3D bird model is established.The perching sequences of the wild eagle are recaptured and regenerated with the proposed 3D bird model.A quasi-steady aerodynamic model is applied in the aerodynamic predictions,a four-step Adams-Bashforth method is used to calculate the ordinary differential equations,thus a BFGS based optimization method is established to predict the perching motions.

一类含扩散与时滞的Prey-Predator模型的周期解

利用上下解方法以及比较原理研究了一类含扩散与时滞的Prey-Predator模型,证明在一定条件下该模型的零平衡态及半平凡周期解的全局稳定性,并获得了这个系统具有一对周期拟解的充分条件.对任意的非负初值函数,这一对周期拟解构成的区间是此系统的一个吸引子.

Preliminarily study on the maximum handling size, prey size and species selectivity of growth hormone transgenic and non-transgenic common carp Cyprinus carpio when foraging on gastropods

The present study preliminarily examined the differences in maximum handling size, prey size and species selectivity of growth hormone transgenic and non-transgenic common carp Cyprinus carpio when foraging on four gastropods species( Bellamya aeruginosa, Radix auricularia, Parafossarulus sinensis and Alocinma longicornis) under laboratory conditions. In the maximum handling size trial, five fish from each age group(1-year-old and 2-year-old) and each genotype(transgenic and non-transgenic) of common carp were individually allowed to feed on B. aeruginosa with wide shell height range. The results showed that maximum handling size increased linearly with fish length, and there was no significant difference in maximum handling size between the two genotypes. In the size selection trial, three pairs of 2-year-old transgenic and non-transgenic carp were individually allowed to feed on three size groups of B. aeruginosa. The results show that the two genotypes of C. carpio favored the small-sized group over the large-sized group. In the species selection trial, three pairs of 2-year-old transgenic and non-transgenic carp were individually allowed to feed on thin-shelled B. aeruginosa and thick-shelled R. auricularia, and five pairs of 2-year-old transgenic and non-transgenic carp were individually allowed to feed on two gastropods species( P. sinensis and A. longicornis) with similar size and shell strength. The results showed that both genotypes preferred thin-shelled Radix auricularia rather than thick-shelled B. aeruginosa, but there were no significant difference in selectivity between the two genotypes when fed on P. sinensis and A. longicornis. The present study indicates that transgenic and non-transgenic C. carpio show similar selectivity of predation on the size-and species-limited gastropods. While this information may be useful for assessing the environmental risk of transgenic carp, it does not necessarily demonstrate that transgenic common carp might have lesser environmental impacts than non-transgenic carp.

Food resource and temporal partitioning amongst a guild of predatory agroecosystem-inhabiting ant species

Prey diversity and temporal foraging patterns of six abundant,predatory ant species were investigated seasonally in an agroecosystem with two main vegetable crops.Pheidole sp.demonstrated the highest predation success and therefore appears to be the dominant species while Tapinoma melanocephalum showed the lowest success under the natural field conditions.Investigation of prey diversity and temporal activity patterns with the null model tests of niche overlap revealed a significant overlap indicating that the activity periods and prey diversity may not be solely influenced by interactions among the co-existing ant species.However,niche partitioning in the daily peak activity periods was demonstrated during all the three seasons(summer,rainy and winter)particularly between Pheidole sp.and T.melanocephalum.Pheidole sp.exhibited a high intensity,broadly extended mono-modal foraging pattern.Camponotus compressus and C.paria showed bi-modality in their foraging activity during the rainy season and mono-modal patterns during summer and winter seasons.Pachycondyla tesserinoda,Tetramorium sp.and T.melanocephalum exhibited peak foraging activities in the morning hours during the summer and rainy seasons.The activity profiles of C.compressus and T.melanocephalum were skewed towards late afternoon hours during the winter season indicating avoidance of foraging activity during the favourable periods when the more aggressive Pheidole sp.is active.In the sponge gourd agroecosystem,the ants captured predominantly hymenopteran,orthopteran and coleopteran insects.While Pheidole sp.hunted mainly the large orthopteran prey,other ant species captured worker ants in the sponge gourd agroecosystem.In the cauliflower agroecosystem,while other species captured prey chiefly belonging to six orders,i.e.,Lepidoptera,Hymenoptera,Coleoptera,Hemiptera,Isoptera and Diptera,Pheidole sp.and P.tesserinoda were the only species to also hunt many orthopteran prey.The agroecosystem-inhabiting ant species prey on a large number and wide variety of insect herbivores as evident from the differences in the peak foraging times and the proportion of each type of prey hunted.Overall,our results indicate that the structure of agroecosystem-inhabiting ant assemblage may be influenced by a variety of factors including competition,temporal heterogeneities,prey availability and its characteristics such as size and mobility.

Experimental clearance rates of Aurelia coerulea ephyrae and medusae,and the predation impact on zooplankton in Jiaozhou Bay

The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence time(t 1/2)for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay.Clearance rates varied widely with prey organisms,but they were not significantly different among various prey concentrations.Medusae captured rotifers,fish larvae and hydromedusae more efficiently than fish eggs,copepods and chaetognaths.Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods.Clearance rate linearly increased with the cross sectional area of A.coerulea(size from 0.3 to 7.1 cm).Water temperature also had a marked effect on clearance rate and this was related to the increased beat frequency as water temperature increased.In early May 2009,A.coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day,but this value was estimated to be more than 0.3 times a day in July.The t 1/2 for copepods was less than 6 d in June and July.Abundances of copepods,hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010(jellyfish non-bloom years).Large predation pressure by the A.coerulea population occurred to control zooplankton communities in Jiaozhou Bay.A.coerulea,when present at a high population level,can be a keystone species in Jiaozhou Bay and control the trophic structure here.

The Global Stability of Predator-Prey System of Gause-Type with Holling Ⅲ Functional Response

This paper deals with the questio n of global stability of the positive locally asymptotically stable equilibrium in a class of predator\|prey system of Gause\|typ e with Holling Ⅲ functional response. The Dulac's criterion is applied and lia punov functions are constructed to establish the global stability.