Shifts in foraging behavior of wintering Hooded Cranes(Grus monacha) in three different habitats at Shengjin Lake, China

Background: Wetland loss and degradation result in a reduction in the availability and quality of food for wintering waterbirds. Birds normally modify their foraging behavior to adapt to variations in food availability. In this study, we compared shifts in foraging behavior of Hooded Cranes(Grus monacha) in three different habitats at Shengjin Lake, China to understand the response of these cranes to changes in habitat.Methods: We investigated the food density and foraging behavior of Hooded Cranes in Shengjin Lake National Nature Reserve from November 2014 to April 2015. We used regression equations to describe the changes in food density. A total of 397 behavioral observations were used in the analyses of their foraging efforts. We fitted a candidate set of generalized mixed linear models to analyze the relationship of foraging efforts and food density. We used a method of information theory to guide the selection of the model and Akaike's Information Criterion to calculate the value of each model. The relationship between food density, disturbances and foraging behavior was illustrated using a generalized linear model.Results: Along with the temporal variation and exploitation of food biomass, the food density varied widely among foraging sites. During the early winter period, foraging efforts were more pronounced in the paddy fields and meadows but not significantly different among the three habitats. The cranes spent more foraging effort in the paddy fields and meadows during the middle stage and in the meadows and mudflats during the late winter. The results of the generalized linear model showed that food density and disturbances had different effects on the rate of foraging success during the winter, while the effect of foraging effort was not significant. Furthermore, the rate of feeding success was markedly affected by disturbances in the paddy fields. The combined action of food density and disturbances had a significant effect on the rate of foraging success in the meadows, while the effect of foraging effort was also not significant in three habitats.Conclusions: Changes in foraging behavior were significant in three habitats, which were affected by food density and disturbances. The rate of foraging success increased in the habitat with low food density and low disturbances to increase the foraging efficiency in the lake. With abundant food and a high level of disturbance, the rate of foraging success decreased to ensure more secure access to food.

Distributional and behavioral responses of the wintering Oriental Storks to drought in China’s largest freshwater lake

Extreme droughts are increasing in frequency and severity globally as a result of climate change.Developing understanding of species’responses to drought is crucial for their conservation,especially in regions experi-encing increased aridity.Although numerous studies have investigated birds’responses to drought,the emphasis has primarily been on landbirds.Drought can significantly alter the wetland environments that waterbirds inhabit,but the response of waterbirds to drought remains understudied.In this study,we surveyed the distri-bution and behavior of Oriental Storks(Ciconia boyciana)in Poyang Lake,which is the largest freshwater lake in China.Results indicate that drought-induced catchment areas at the lowest water level limited the total popu-lation size of Oriental Storks in the sub-lakes.Sub-lakes with large catchment areas at the lowest water level demonstrated a capacity to support a larger population of wintering Oriental Storks.Over time,Oriental Storks exhibited a gradual concentration in Changhu Lake,characterized by larger catchments,after resource depletion in sub-lakes with smaller catchments.Additionally,the duration of Oriental Storks’vigilance and moving be-haviors decreased significantly compared with that observed before the drought.After the drought,Oriental Storks increased their foraging efforts,as evidenced by increased presence in deeper water and reaching their heads and necks into deeper water to forage,higher search rates,but lower foraging rates.In accordance with area-restricted search theory,reductions in habitat quality resulting from drought,including extensive fish die-offs,forced Oriental Storks to increase their foraging efforts.Sustaining a specific water area in sub-lakes during droughts can preserve resource availability,which is crucial for the conservation of Oriental Storks.Imple-menting measures such as water level control and micro-modification of lake bottoms in sub-lakes might mitigate the impact of drought on the piscivorous Oriental Storks.

The influence of past experience on wasp choice related to foraging behavior

Memory has been little studied in social wasps. Vespula germanica （Fab.） （Hymenoptera： Vespidae） frequently revisits nondepleted food sources, making several trips between the resource and the nest. In this study, we analyzed this relocating behavior in order to evaluate whether this species is capable of remembering an established association after 1 h. To this end, we trained wasps to feed from a certain array. Then it was removed, setting it up again 1 h later, but this time 2 baited feeders were put in place, one at the original feeding site and the other opposite the first. We recorded the proportion of returning foragers, and their choice of feeder, after either 1 or 4 feeding trials. After 1 h, 78% of wasps trained with 4 feeding trials and 65% trained with 1, returned to the experimental area. Furthermore, during the testing phase, wasps trained with 4 feeding trials collected food from the previously learned feeder significantly more frequently than from the nonlearned one （P 〈 0.05）. In contrast, wasps that had been trained only once chose both feeders equally. Thus, memory retrieval could be observed 1 h after wasps had collected food on 4 consecutive occasions, but not after only 1. To our knowledge, this is the first study showing that V. germanica is capable of remembering an association 1 h after the last associative event, demonstrating that 1 h does not impair memory retention if4 feeding experiences have occurred.

Long-term spatial memory in Vespula germanica social wasps： the influence of past experience on foraging behavior

Social insects exhibit complex learning and memory mechanisms while for- aging. Vespula germanica （Fab.） （Hymenoptera： Vespidae） is an invasive social wasp that frequently forages on undepleted food sources, making several flights between the resource and the nest. Previous studies have shown that during this relocating behavior, wasps learn to associate food with a certain site, and can recall this association 1 h later. In this work, we evaluated whether this wasp species is capable of retrieving an established association after 24 h. For this purpose, we trained free flying individuals to collect proteinaceous food from an experimental plate （feeder） located in an experimental array. A total of 150 individuals were allowed 2, 4, or 8 visits. After the training phase, the array was re- moved and set up again 24 h later, but this time a second baited plate was placed opposite to the first. After 24 h we recorded the rate of wasps that returned to the experimental area and those which collected food from the previously learned feeding station or the nonlearned one. During the testing phase, we observed that a low rate of wasps trained with 2 collecting visits returned to the experimental area （22%）, whereas the rate of returning wasps trained with 4 or 8 collecting visits was higher （51% and 41%, respectively）. Moreover, wasps trained with 8 feeding visits collected food from the previously learned feeding station at a higher rate than those that did from the nonlearned one. In contrast, wasps trained 2 or 4 times chose both feeding stations at a similar rate. Thus, significantly more wasps returned to the previously learned feeding station after 8 repeated foraging flights but not after only 2 or 4 visits. This is the first report that demonstrates the existence of long-term spatial memory in V. germanica wasps.

A short note on extractive foraging behavior in gray snub-nosed monkeys

Extractive foraging(EF)involves the exploitation of hidden or embedded foods,generally any food that is not visible to the naked eye.Therefore,EF is particularly important for survival in marginal habitats as it provides seasonal fallback foods in low food availability seasons.Although many studies consider primates’EF behavior and category,colobine species are usually categorized as non-extractive foragers and few studies quantitatively examine their EF behavior.In this study,we examined the EF behavior of one colobine species,the gray snub-nosed monkey(Rhinopithecus brelichi),at Yangaoping in Fanjingshan National Nature Reserve,Guizhou.We recorded 6 categories of EF behaviors.The most frequently sought-out foods were seeds,young bamboo and invertebrates.Extracted foods accounted for an average of 26.02%of feeding records.As the monkey engages in little EF behavior in the winter when the food availability is low,these results seem to do not support the hypothesis that EF serves to secure additional resources during lean times in marginal or seasonal habitats.According to these findings,we suggest R.brelich should be considered as an extractive forager.Our study also highlights the need for increased representation of colobines in the EF literature to better inform the discussion concerning its link to primate brain evolution.

Effect of conspecific and heterospecific urine odors on the foraging behavior of the golden spiny mouse

The common spiny mouse(Acomys cahirinus)inhibits the foraging activity of the golden spiny mouse(A.russatus).These two sympatric species of spiny mice,which are considered habitat competitors,occur in extreme arid environments.To test this theory of competition,the influence of urinary odors of both conspecific and heterospecific mice on the foraging behavior of A.russatus was studied under controlled laboratory conditions.Twenty adult males,born in captivity and unfamiliar to the odors of the donor mice,were tested in 3 experimental conditions choosing between 2 seed patches that were scented with urine of either heterospecifics(A.cahirinus),conspecifics(A.russatus)or controls(odors of the tested individual).Of the 20 males,12 were also tested with urine of unfamiliar gerbils,bushy-tailed jird,considered as competitors in the field.Both conspecific and heterospecific urine samples from Acomys significantly reduced foraging behavior of A.russatus when compared to the control odor.The inhibitory effect of the Acomys urine does not result from the novelty of chemical stimuli of the urine because no effect was shown with unfamiliar gerbil urine.The findings are in accordance with the general theory that A.cahirinus dominates the foraging activity of A.russatus.We hypothesize that chemical cues in the urine of Acomys spp.might induce a negative effect on the foraging behavior of A.russatus.

Scaly-sided Merganser(Mergus squamatus)equalizes foraging costs with depth by switching foraging tactics

Throughout evolutionary history,animals are finely tuned to adjust their behaviors corresponding to environmental variations.Behavioral flexibility represents an important component of a species'adaptive capacity in the face of rapid anthropogenetic environmental change,and knowledge of animal behaviors is increasingly recognized in conservation biology.In aquatic ecosystem,variation of water depth is a key factor affecting the availability of food;thus,the foraging behaviors of many waterbirds,especially piscivores.In this study,we compared the foraging behaviors of the Scaly-sided Merganser(Mergus squamatus),an endangered migratory diving duck endemic to East Asia,in habitats with different water depths(Shallow waters:0–40 cm;Deep waters:40–300 cm),using video camera records obtained from the known wintering sites during three winters from 2018 to 2020.Further,the energy expenditure of foraging behavior profile and energy intake based on fish sizes were calculated to study the foraging energetics.In total,200 effective video footages that contained 1086 min with 17,995 behaviors and 163 events of catching fish were recorded.Results showed that:1)time length for fishing(including eye-submerging,head-dipping,diving and food handling)of M.squamatus in shallow waters was significantly more than in deep waters;2)M.squamatuss spent significantly more time for preparing(including vigilance,preening and swimming)in deep waters than in shallow waters;3)the mean catch rate was 0.28 fish/min in shallow waters,which is significantly higher than the value of 0.13 fish/min in deep waters;4)despite the distinct foraging behavior profiles and energy intakes,M.squamatus showed similar energetics in shallow and deep waters.We concluded that M.squamatus is a good example of behavioral flexibility that aligns with expectations of optimal foraging theory,in that it behaves in accordance to resource availability in different environments,resulting in high foraging efficiency.

Nutrition Analysis of Forage Plants and Foragnig Behavior of Mongolian Gazella

The study on winter food constitution of Mongolian gazella (Procapra gutturosa) was conducted in Hulunbeir grassland(Xinbarhuyou Banner, Hulunbeir League, Inner Mongolia) from spring 1994 to summer 1995. With microhistological analysis technique of feces, 21 plant species were identified to be availlable for Mongolian gazella as forage in winter and their nutritive trait were analyzed. Some foraging behavior of Mongolian gazella were also discribed.

Activity Recording of Free-Ranging Tri-spine Horseshoe Crabs in the Southeastern Coast of Sabah,Borneo

In Inderasabah(southeast Sabah),tri-spine horseshoe crab Tachypleus tridentatus was observed for their locomotion activity using data loggers from September to November in 2015.A female with acceleration and depth-temperature loggers and five males with acceleration loggers were recaptured between 10 and 49 days after their release.From the record of 194 activity days that involve all six T.tridentatus,four horseshoe crabs,including the female,were active throughout the 24.0 h cycle,whereas the activity of the remaining two males was consistent with the 12.4 h cycle.Using the 40-day recording,three horseshoe crabs,including the female,were primarily active around the new moon and full moon,but they were dormant around the first and third quarter moon days.The female spent much time in shallow shores(depth<0.3 m)during the new moon and full moon.This result indicated that the female attempted to spawn in a minimum of three spring tide periods while lingering in the vicinity.Meanwhile,after spawning,the female spent time foraging in shallow water(depth 0.3–18 m).As for the two male individuals,their activity was consistent with semi-lunar periodicity.Therefore,both of them were in amplexus.In addition,a solitary male individual was active only during the first and third quarter moon days.Through activity recording,all the T.tridentatus in Inderasabah was active during daytime and nighttime.This result was contrary to T.tridentatus activity cycles in western Japan,where the species was found to be primarily nocturnal.Perhaps,the regional differences in activity cycles for T.tridentatus were related to their population adaptation toward water temperature,depth,and prey-searching periods.

The compromising foraging of a clonal submerged plant in variable environments of substrate type and light condition: a simulation study

Aims Foraging behavior was concerned less in plants especially for clonal aquatic species.The goal of this study was to test the foraging behav-ior and the function of phenotypic plasticity of a clonal submerged plant,Potamogeton maackianus A.Benn in variable manipulative environments.Methods To explore the foraging behavior of a clonal submerged plant,clones of P.maackianus were cultivated in variable environments of different substrate types and light conditions.We measured bio-mass,specific root area(SRA),specific root length(SRL),branch-ing angle of the ramet,chlorophyll content of apical leaves(CCAL),Fv/Fm(chlorophyll fluorescence parameter that indicates maximal photosystem II(PS II)efficiency)and biomass distribution in soil and light contrast treatments after harvest.Important Findings We found that the atypical non-clonal-like foraging behavior homogenized the performance of the stoloniferous clonal spe-cies,P.maackianus,in the measurement of biomass in our study.Substrate type had significant effects on most traits of P.maackianus,except on total biomass,shoot biomass distribution and CCAL.Patchy substrate mediated more root distribution into sand patch rather than into clay patch.Increase of SRA,SRL and Fv/Fm might be adaptive to substrate heterogeneity.Moreover,substrate hetero-geneity induced‘sidewalk’stolon lineage on the edge of sand patch along the patch border.Light condition only had significant effects on branching angle,shoot biomass distribution and Fv/Fm.Shade led to more shoot assignment in light-rich zone than in light-poor zone.Potamogeton maackianus adjusted the branching angle of ramet rather than clonal exploitation in heterogeneous substrates with patchy shade.Moreover,shade led to higher Fv/Fm.A com-promising foraging strategy promoted P.maackianus to escape unfa-vorable environments.Phenotypic plasticity,which maximized the performance of P.maackianus in the measurement of biomass in variable environments,may explain its domination in some shallow lakes of the middle and lower reaches of Yangtze River.

Evidence of associative blocking during foraging in the social wasp Vespula germanica

While foraging,Vespula germanica usually return to abundant food sites.During this relocation behavior,these wasps learn to identify contextual cues associated with food position.We analyzed associative blocking in this species,that is,how an association with a conditioned stimulus(CS1)blocks subsequent learning when a novel stimulus(CS2)is added on a second foraging visit.Three groups of wasps(A,B,and C;total 74 individual wasps)were observed while collecting meat during one or two consecutive visits.In group A,an environmental cue(CS1)was paired with food placed at a specific site,and on the second visit,a second cue(CS2)was added while food remained in the same position.In a subsequent testing phase,CS1 was removed and the food source displaced nearby.We then recorded the number of hovers performed over the empty dish(previously baited).Group A wasps appeared to ignore the addition of CS2 on their second visit because they performed fewer hovers over the learned site.For group A,the duration of the decision-making process to finally fly toward the baited dish was shorter than when CS1 and CS2 were presented together on their first visit(group B).This is the first study to demonstrate the occurrence of associative blocking in vespids,confirming that a prior foraging experience influences subsequent food relocation in V.germanica.Our findings reveal that first learning episodes block further associations with novel contextual cues,contributing to understanding of complex cognitive processes involved in V.germanica´s foraging behavior.

Neighborhood effects on the tannin-related foraging decisions of two rodent species under semi-natural conditions

Neighborhood effects on seed predation and dispersal processes are usually seed-characteristic-dependent;however,how seeds with certain characteristics affect the foraging behavior of rodents in relation to other seeds nearby is unclear.Because large differences in seed characteristics between neighboring seeds may lead to significant differences in rodent foraging preferences,we hypothesized that neighborhood effects were more likely to be detected when paired seeds differed in seed characteristics.We investigated the foraging decisions of two rodent species,the red spiny rat Maxomys surifer and the Chinese white-bellied rat Niviventer confucianus,in semi-natural enclosures by presenting them with artificial seeds containing different levels of tannin(0,3%,and 6%tannin).Both rodents showed similar preferences and preferentially consumed high-tannin seeds(6%tannin)and scatter hoarded low-tannin seeds(0 tannin).The scatter hoarding of low-tannin(0 tannin)and high-tannin(6%tannin)seeds was significantly higher when these seeds were neighboring higher-tannin seeds than when they neighbored lowertannin seeds,whereas the scatter hoarding of intermediate-tannin seeds(3%tannin)varied little when they had different neighbors.High-tannin-seed(6%tannin)scatter hoarding was lowest when they neighbored low-tannin seeds(0 tannin),while low-tannin-seed(0 tannin)scatter hoarding was highest when they neighbored high-tannin seeds(6%tannin).Therefore,the seeds that the rodents scatter hoarded were next to(neighbored)seeds that they preferred to eat immediately,and vice versa.Our findings suggest that seed neighborhood effects affect rodent foraging behavior and the relationship between plants and rodents,and may have a profound effect on the regeneration and spatial structure of plant communities.

A suture-free, shape self-adaptive and bioactive PEG-Lysozyme implant for Corneal stroma defect repair and rapid vision restoration

limitation of donor tissue shortage clinically. In addition, suturing-needed transplantation potentially causes postoperative complications. Herein, we design a PEG-Lysozyme injective hydrogel as a suture-free, shape self-adaptive, bioactive implant for corneal stroma defect repair. This implant experiences a sol-gel phase transition via an in situ amidation reaction between 4-arm-PEG-NHS and lysozyme. The physicochemical properties of PEG-Lysozyme can be tuned by the components ratio, which confers the implant mimetic corneal modulus and provides tissue adhesion to endure increased intraocular pressure. In vitro tests prove that the implant is beneficial to Human corneal epithelial cells growth and migration due to the bioactivity of lysozyme. Rabbit lamellar keratoplasty experiment demonstrates that the hydrogel can be filled into defect to form a shape-adaptive implant adhered to native stroma. The implant promotes epithelialization and stroma integrity, recovering the topology of injured cornea to normal. A newly established animal forging behavior test prove a rapid visual restoration of rabbits when use implant in a suture free manner. In general, this work provides a promising preclinical practice by applicating a self-curing, shape self-adaptive and bioactive PEG-Lysozyme implant for suture-free stroma repair.

Effects of soil substrate heterogeneity and moisture on interspecific competition between Alternanthera philoxeroides and four native species

Aims Clonal plant species have the potential for high relative performance in heterogeneous environments,and this might increase the com-petitive ability and invasiveness of introduced clonal plant species.It was hypothesized that clonal species whose performance responds more to heterogeneity of a resource have higher competitive ability in habitats where this resource is more heterogeneous and that this relationship is stronger when other resources are less limiting.Methods To test these hypotheses,the perennial clonal herb Alternanthera philoxeroides,which is invasive in China,was grown alone or with each of four clonal perennial,co-occurring herbs native to China,i.e.Alternanthera sessilis,Cynodon dactylon,Hemarthria altissima and Wedelia chinensis.Plants were given homogeneous or het-erogeneous soil substrate crossed with low and high levels of soil moisture.Important Findings Effects of heterogeneity on the accumulation of mass and ramets and on competitive effect and response of A.philoxeroides differed between native species and interacted with effects of soil moisture.A.philoxeroides reduced the final total mass or ramet number of the native species except A.sessilis,and the negative competitive effects on H.altissima and C.dactylon were more pronounced in heterogeneous than in homogeneous soil.Competitive response of A.philoxeroides was more negative to A.sessilis than to the other native species.Across native species,the competitive response of A.philoxeroides was more negative in heterogeneous than in homo-geneous soils at low moisture level,but the reverse was true at high moisture level.Results do not consistently support either hypoth-esis,but do suggest that competitive ability can be partly explained by individual species traits such as size,and that some competi-tive effects and responses are emergent properties of interspecific interactions.

Subterranean termites （Isoptera： Rhinotermitidae）： Exploitation of equivalent food resources with different forms of placement

Coptotermes gestroi and Heterotermes tenuis have been described as important urban pests in Brazil. The establishment of control technologies using baits that consider the social behavior of termites requires a better knowledge of their foraging behavior. Thus, this study analyzed the feeding behavior of these species with three different forms of food placement： food on the surface of a substrate and food either partially or completely buried in the substrate. Experimental arenas were composed of a central chamber connected to three food chambers. Each central chamber contained 550 foragers of C. gestroi or 517 foragers of 11. tenuis. Blocks of Pinus elliottii were placed in the different food chambers. After 28 days, the consumption of each wood block and the percentage of foraging individuals recruited for food chambers were verified in relation to the total survival rate obtained for each one of the 20 replicates. Results showed that completely buried food was most consumed for H. tenuis and presented a higher recruitment rate of workers and soldiers for both species. Although the consumption had non-significant differences for C. gestroi, these termites exhibited a tendency to prefer completely buried food. In these conditions, it can be concluded that the forms of food placement used in the present research influenced the recruitment of individuals for both species. Data also suggests that when the foraging subterranean termites find food resources in the tunneling substrate, they tend to concentrate their efforts on it, a behavior regime that reduces exposure to external environment.

Grassland-based ruminant farming systems in China: Potential, challenges and a way forward

With an increasing demand for high-quality,eco-friendly food products and growing concerns over ecological conservation,the development of ecology-based alternatives for ruminant production in China is urgently needed.This review discusses the capabilities for integrating grassland grazing into existing livestock farming systems to meet the contemporary human needs for high-quality foods and ecologically stable environments.Additionally,this review provides a critical analysis of the challenges and future directions associated with grassland-based ruminant farming systems.Integrating nutritional manipulation with grazing manipulation is critical for improving the productivity of grassland-based ecosystems and natural ecological functions.Biodiversity is the primary determinant of grassland ecosystem functions,while the composition and function of rumen microbiomes determine ruminant production performance.Future studies should focus on the following aspects:1)how livestock grazing regulates grassland biodiversity and the mechanisms of grassland biodiversity maintenance,offering an important scientific basis for guiding grazing manipulation practices,including grazing intensity,livestock types,and grazing management practices;to 2)characterize the microbial ecology within the rumen of grazing ruminants to offer clarified instruction for the nutritional manipulation of grazing ruminants.Our recommendation includes creating a transdisciplinary system that integrates ecology,animal nutrition,and animal behavior to develop grassland-based ruminant farming systems sustainably,thereby achieving high-quality animal production and environmentally sustainable goals.

Encounters with aphid predators or their residues impede searching and oviposition by the aphid parasitoid Aphidius ervi （Hymenoptera： Aphidiinae）

Intraguild predation （IGP） can be an important factor influencing the effective- ness of aphid natural enemies in biological control. In particular, aphid parasitoid foraging could be influenced by the presence of predators. This study investigated the effect of larvae of the predatory hoverfly Episyrphus balteatus DeGeer （Diptera： Syrphidae） and the multicolored Asian ladybird Harmonia axyridis Pallas （Coleoptera： Coccinellidae） on the foraging behavior of the aphid parasitoid, Aphidius ervi Haliday （Hymenoptera： Aphidiidae） in choice experiments using a leaf disc bioassay. Wasp response to chemical tracks left by those predator larvae was also tested. Parasitoid behavior was recorded using the Observer （Noldus Information Technology, version 5.0, Wageningen, the Netherlands）. The experiments were conducted under controlled environmental conditions using leaves of the broad bean plant, Viciafaba L. （Fabaceae） with Myzus persicae Sulzer （Homoptera： Aphididae） as the host complex. A. ervi females avoided aphid patches when larvae of either predator were present. A similar avoidance response was shown by A. ervi to aphid patches with E. balteatus larval tracks, whereas no significant response was observed to tracks left by H. axyridis larvae. It was concluded that IG predator avoidance shown by the aphid parasitoid A. ervi may be a factor affecting their distribution among host patches.