Feeding ecology of hairtail Trichiurus margarites and largehead hairtail Trichiurus lepturus in the Beibu Gulf, the South China Sea

We evaluated the feeding ecology of largehead hairtail (Trichiurus lepturus) and hairtail (T. margarites). We collected specimens from fishing ports in the Beibu Gulf (Gulf of Tonkin) from October 2008 to September 2009 and analyzed their gut contents. We collected 857 T. lepturus and 666 T. margarites samples. The number of stomachs examined in this study was sufficient to describe the monthly and ontogenetic diet shifts for the two species, as indicated by the trophic diversity curves. T. lepturus was a general omnivore, feeding primarily on Bregmaceros rarisquamosu, Decapterus maruadsi, and Acetes chinensis. Conversely, T. margarites preyed primarily on D. maruadsi, B. rarisquamosus, B. nectabanus, and A. chinensis. Both species exhibited distinct ontogenetic diet shifts. Although the two hairtail specie fed on similar sources in the same habitat, the diet overlap was relatively low. Our results suggest that hairtail play an important role in controlling small pelagic and benthic fish populations in the gulf. This trophic correlation shall be used for developing a marine ecosystem model for the Beibu Gulf.

Diet and feeding ecology of invasive icefish Neosalanx taihuensis in Erhai Lake,a Chinese plateau mesoeutrophicated lake

A comprehensive study of the invasive icefish Neosalanx taihuensis feeding ecology in Erhai Lake was conducted from November 2009 to October 2010. Prey items in the guts of the icefish sampled varied significantly according to season. This finding suggests a relationship between fluctuations in available prey in the environment and selective feeding by icefish. N. taihuensis preferred large-sized zooplankton, such as Daphnia and calanoids. Additionally, the gut fullness values differed significantly （P〈0.001） among sampling times. To compare the values at different times, samples were taken over a 24 h period every 2 months for the entire year. The feeding activities of the fish were concentrated either in the morning （8：00） and/or at dusk （20：00）, except in September 2010. This finding can be explained primarily by the variation in optimum light intensity. Daily N. taihuensis zooplankton consumption varied significantly, both diurnally and among seasons. The daily consumption values ranged from 0.089 to 0.237 g （wet weight） per 100 g wet fish weight in temperatures between 11.50℃ and 24.68℃. This is the first report of diel feeding periodicity and daily food consumption of icefish in their invaded ecosystems.

Progress of Chinese zooplankton ecology research in Prydz Bay, Antarctica

Zooplankton are considered an important trophic link between primary producers and higher trophic level species in the Southern Ocean ecosystem. Since 1989, when the Chinese Antarctic Zhongshan Station was built, zooplankton have regularly been sampled and investigated in Prydz Bay through oceanographic surveys of each Chinese National Antarctic Research Expedition. This review summarizes the main results from zooplankton ecology studies conducted in Prydz Bay by Chinese researchers. Major topics covered in this review are： （1） a description of the biology and ecology of Antarctic krill （Euphausia superba）, the key zooplankton species of the Southern Ocean ecosystem; （2） zooplankton community structure, including the horizontal distribution in the epipelagic region and vertical distribution between 0-1500 m; （3） feeding ecology of dominant species such as Antarctic krill, salps and copepods; （4） a short introduction to the molecular research; and （5） prospects for future research.

Feeding a Need A Chinese agricultural expert popularizes ecological livestock farming in Sao Toméand Príncipe

Toyamara Da Vera Cruz is all ears when Peng Yansen, her teacher, glves instructions. Although she has extensive experience in farming herself. coming from a long line of livestock breeders, Cruz is now learning a new skill from Peng.

Diet and Food Consumption of the African Catfish, <i>Chrysichthys nigrodigitatus</i>Lacépède (1803) (Siluriformes: Claroteidae), from the Hydrosystem Lake Togo-Lagoon of Aného (South of Togo)

Catfishes belonging to the genus Chrysichthys are generally important fish species in inland water bodies of Africa because of their high commercial value. Among them, C. nigrodigitatus could represent, at certain periods of the year the highest biomass of the littoral ichthyofauna, accounting for 17 to 43.8% of total catches. In this paper, its diet in the hydrosystem Lake Togo-Lagoon of Aného was investigated focusing on how differences in diet and food consumption are related to size, season and sexual maturity. A total of 195 males and 137 females were sampled from January to December 2017. The digestive tract of each individual was dissected and its content was analyzed, using indexes of stomach contents analysis method. Diet variability in relation to season and biometric parameters was also studied. About 99 stomachs were empty with an overall vacuity index of 29.82%. However, vacuity index was found to vary in relation to fish size and months. The fish has been found to be omnivorous with a carnivorous tendency consuming a wide range of prey items (H = 3.34). Juvenile and adult freshwater clams (Galatea paradoxa) were the numerical dominant preys (%N = 44%) while the penaeid shrimps (Farfantepenaeus notialis) with an annual frequency of occurrence (Fo) of 49.36% and all species confused of fish (33.91%) were the most preferred preys. The index of relative importance (IRI) reveals that freshwater clam (40.49%), penaeid shrimps (35.85%) and all species confused of fish (14.58%) were the most important preys of C. nigrodigitatus. The dominance of Malacostraca and Mollusca in the diet of C. nigrodigitatus in the hydrosystem Lake Togo-Lagoon of Aného is likely one of the more important considerations for future management plans.

Abundance of White-fronted Parrots and diet of an urban parrot assemblage(Aves:Psittaciformes)in a green Neotropical city

Urban ecosystems are evolutionarily recent novel environments acting as biodiversity filters.Psittacidae birds are considered successful urban adapters mainly due to their generalist feeding and opportunistic behavior,allowing them to occupy environments from cold temperate to dry xeric areas.Therefore,it is important to understand how these species interact in the urban environment.We studied the interannual(2013–2016)abundance of the White-fronted Parrot(Amazona albifrons)in the Neotropical cities of Xalapa and Coatepec,in Central Veracruz,México.Additionally,we studied the feeding ecology during 13 months of 6 parrot species detected in the city of Xalapa.The abundance of the White-fronted Parrot was significantly higher in Xalapa than in Coatepec,and it was homogeneous across years.Non-native plants represented 30–41%of Psittacidae diets in Xalapa,where seeds were the most commonly consumed resource.We recorded the highest Psittacidae species richness and highest diet overlap among species by the end of the dry season(April–May).The White-fronted Parrot had the highest plant richness in its diet,followed by the Monk Parakeet(Myiopsitta monachus)and the Green Parakeet(Psittacara holochlorus);yet,the White-fronted Parrot had a specialized diet dominated by two plant species(Grevillea robusta and Ficus aurea).The diet overlap among the three above-mentioned parrot species was not significantly different to a null model,where the White-fronted Parrot and the Monk Parakeet overlapped during the months of February,April,June,and September.The White-fronted Parrot is an urban adapter that has successfully expanded its geographic range via natural means and by human activities.The invasive Monk Parakeet is currently restricted to one park in Xalapa,and it has remained in that stage for many years(i.e.,pre-expansion phase).Exotic plant species in Xalapa represent∼55%of the woody vegetation,some of which have longer flowering and fruiting periods that may have aided the successful establishment of parrot species in urban environments.

Ecology and management of rodents in no-till agriculture in Washington, USA

No-till farming is an important approach to sustainable agriculture because it can conserve soil and water resources.Unfortunately, rodent populations can thrive under no-till conditions because burrow systems are not disrupted byannual plowing and plant residues build-up on the surface, providing cover and insulation. This can result in substantialcrop damage. We assessed rodent populations, habitat use, food habits, and crop damage in a no-till croppingsystem in Washington, USA. We also conducted preliminary trials of methods to reduce rodent populationsand crop damage. In the fall, many more rodents were captured in fields with unharvested crops than in fieldscontaining only plant stubble, suggesting that rodents leave fields after crop harvest, providing that suitable habitatsare nearby, even when adequate cover is still available in harvested crop fields. By spring, the number of volescaptured was much lower relative to fall. Despite this, capture rates were much higher in surrounding permanentgrass areas than in crop (barley, wheat, pea) fields, suggesting that these grassy areas serve as refugia for rodents.Furthermore, the permanent grass cover type was the landscape variable most associated with rodent capture rates.In three winter pea fields, rodents removed 5–15% of the pea plants over winter. Examination of stomach contentsrevealed that voles mainly fed on grain plants in spring, but that their diet was more diversified in fall. Deer micefed heavily on grain plants in both spring and fall, but also used insects as food. Metal barrier exclosures (9 m × 9m), extending above and below ground, did not prevent access by rodents. Rodent populations in areas treated withzinc phosphide on grain were comparable to untreated areas 1 year after application of the rodenticide, perhaps becauseof immigration and recruitment, suggesting that baiting does not provide a long-term solution to rodent damagein no-till agricultural fields.

Coping with drought?Effects of extended drought conditions on soil invertebrate prey and diet selection by a fossorial amphisbaenian reptile

Arid climates are characterized by a summer drought period to which animals seem adapted.However,in some years,the drought can extend for unusually longer periods.Examining the effects of these current extreme weather events on biodiversity can help to understand the effects of climate change,as models predict an increase in drought severity.Here,we examined the effects of“unusual”extended drought on soil invertebrate prey availability and on diet composition(based on fecal contents)and diet selection of a fossorial amphisbaenian,the checkerboard worm lizard Trogonophis wiegmanni.Weather data show interannual variations in summer drought duration.The abundance and diversity of soil invertebrates in spring were high,and similar to those found in a“normal”early autumn,after some rain had ended with the summer drought.In contrast,in years with“unusual”extended drought,abundance,and diversity of soil invertebrates in early autumn were very low.Also,there were seasonal changes in amphisbaenians’diet;in autumn with drought,prey diversity,and niche breadth decreased with respect to spring and autumns after some rain had fallen.Amphisbaenians did not eat prey at random in any season,but made some changes in prey selection that may result from drought-related restrictions in prey availability.Finally,in spite that amphisbaenians showed some feeding flexibility,their body condition was lower in autumn than in spring,and much lower in autumn with drought.If extended drought became the norm in the future,amphisbaenians might suffer important negative effects for their health state.

Prey decline leads to diet shift in the largest population of Indo-Pacific humpback dolphins?

The Pearl River Delta(PRD)region on the southeast coast of China has long been known as a highly productive fishing ground.Since the late 1980s,fishing pressure in the PRD has been intense,which warrants concerns of potential fishery-related impacts on the food resources and foraging ecology of apex marine predators in this region,such as the Indo-Pacific humpback dolphin(Sousa chinensis).In this study,we examined 54 stomachs with food remains,collected from beached carcasses of humpback dolphins recovered during fifteen years between 2003 and 2017.The 6043 identified prey items represent 62 teleost taxa,primarily small estuarine fish,but also larger reef fish.The dolphins appear to be opportunistic foragers,hunting across the water-column,with preference for shoaling and meaty fishes(e.g.Collichthys lucidus IRI%=38.6%,Johnius belangerii IRI%=23.1%,Mugil cephalus IRI%=14.0%).Our findings suggest a dietary shift in recent years,from primarily demersal(as previously reported)to greater intake of neritic and pelagic fish.Dolphin foraging group size has decreased in recent years,which corresponds with declining size and numbers of prey items retrieved from dolphin stomachs.We suggest that these are indicators of declining food resources.Faced with a shortage of preferred prey,humpback dolphins may have broadened their dietary spectrum to maintain their daily energy intake,while their foraging group size decreased in response to the altered tradeoff between the costs and benefits of group foraging.

Slow-growth high-mortality： A meta-analysis for insects

The slow growth-high mortality hypothesis （SG-HG） predicts that slower growing herbivores suffer greater mortality due to a prolonged window of vulnerability. Given diverse plant-herbivore-natural enemy systems resulting from different feeding ecologies of herbivores and natural enemies, this hypothesis might not always be applicable to all systems. This is evidenced by mixed support from empirical data. In this study, a meta- analysis of the SG-HM hypothesis for insects was conducted, aiming to find conditions that favor or reject SG-HM. The analysis revealed significant within- and between-group heterogeneity for almost a11 explanatory variables and overall did not support SG-HM. In this analysis, SG-HM was supported when any of the following 5 conditions was met： （1） host food consisted of artificial diet; （2） herbivore growth was measured as larval mass; （3） herbivores were generalists; （4） no or multiple species of natural enemies were involved in the study; and （5） parasitoids （i.e., parasitic insects） involved in the study were gregarious. SG-HM was rejected when any of the following 5 conditions was met： （1） herbivores were from the order Hymentoptera; （2） parasitoids from more than 1 order caused herbivore mortality; （2） parasitoids were specialists; （3） parasitoids were solitary; （4） parasitoids were idiobionts or koinobionts; and （5） single species of natural enemy caused mortality of specialist herbivores. All known studies investigated herbivore mortality for a short period of their life cycle. Researchers are encouraged to monitor herbivore mortality during the entire window of susceptibility or life cycle using life tables. Studies involving multiple mortality factors （i.e., both biotic and abiotic） or multiple natural enemy species are also encouraged since herbivores in nature face a multitude of risks during the entire life cycle. More comprehensive studies may increase our understanding of factors influencing the relationships between herbivore growth and mortality.

Does urbanization influence the diet of a large snake？

Urbanization facilitates synanthropic species such as rodents, which benefit the diets of many predators in cities. We investigated how urbanization affects the feeding ecology of dugites Pseudonaja affi- nis, a common elapid snake in south-west Western Australia. We predicted that urban snakes： 1） more frequently contain prey and eat larger meals, 2） eat proportionally more non-native prey, 3） eat a lower diversity of prey species, and 4） are relatively heavier, than non-urban dugites. We analyzed the diet of 453 specimens obtained from the Western Australian Museum and opportunistic road-kill collections. Correcting for size, sex, season, and temporal biases, we tested whether location influenced diet for our 4 predictions. Body size was a strong predictor of diet （larger snakes had larger prey present, a greater number of prey items, and a greater diversity of prey）. We identified potential collection biases： urban dugites were relatively smaller （snout-vent length） than non-urban specimens, and females were relatively lighter than males. Accounting for these effects, urban snakes were less likely to have prey present in their stomachs and were relatively lighter than non-urban snakes. Other urban-adapted carnivores appear to benefit from urbanization through increased food supplementation, but we found the opposite of this： urban dugites were less likely to contain a meal, and their meals were smaller, indicating they did not make greater use of synanthropic species than was evident for non-urban snakes. In contrast to other carnivores, snakes do not appear to fit a consistent directional pattern for size differences between urban and non-urban populations.

Diet of Chinese skink, Eumeces chinensis: is prey size important?

The diet of the skink,Eumeces chinensis(Lacertilia:Scincidae),in Xiamen(Amoy),China was examined using stomach analysis during April and May,and its selection of prey size was tested by feeding trials.Insects(primarily Coleoptera,Lepidoptera,and Orthoptera),gastropods and arachnids constituted most of the E.chinensis diet,but earthworms,leeches,crustaceans and fish were also consumed.In the field,male skinks ate more prey items that were 11–20 mm in length than other size classes.When presented with a choice of different-sized prey in the laboratory,male E.chinensis exhibited a strong preference for prey items 11–20 mm in length over other size classes.The relationship between prey size and handling time was exponential,indicating that there is an upper limit to the ability of E.chinensis to process prey.Mean energy intake for handling different-sized prey showed that selection of midsize-class prey items would provide male E.chinensis with the most energy-efficient prey option.These results indicate that prey size selection in E.chinensis favors maximization of rates of energy intake,which is in agreement with optimal foraging theory.

Exploiting a readily available but hard to digest resource:A review of exudativorous mammals identified thus far and how they cope in captivity

Gum is a widely available carbohydrate,composed mainly of non-digestible structural carbohydrates.No mammalian enzymes can digest gum;therefore,a mammal ingesting gum must rely on microbial fermentation to access the energy it possesses.Gums are relatively nutrient poor.Despite this,some mammals have evolved to exploit this food resource.We aim to review the literature for all mammal species which have been recorded to ingest gum,whether quantified or not,and discuss this in the context of their evolutionary adaptations.We also investigated the recommended captive diets for these species to look at whether gum is recommended.We conducted a literature search on ISI Web of Knowledge to tabulate all mammal species observed ingesting gum and classified them as obligate,facultative or opportunistic feeders.We encountered 94 mammal species that eat gum in the wild(27 obligate feeders,34 facultative feeders and 33 opportunistic feeders).Obligate feeders have entirely evolved to exploit this resource but were found to not be given gum in captivity,which may explain why they are failing to thrive,as opposed to facultative feeders,which have fewer issues.Gum may be necessary for the health of obligate feeders in captivity.Future research should focus on the physiological effects that gum ingestion poses on different digestive systems.

Demography, reproductive biology and diet of the bushveld gerbil Tatera leucogaster (Rodentia: Gerbillinae) in the Lake Rukwa valley, south-western Tanzania

Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The gerbilswere collected over a 2-year period using Sherman live and Victor hold-fast snap traps in permanent 4.5-ha grids. Atotal of 664 individuals were captured over 13 650 trap nights, giving an overall trap success rate of 4.9%. Trapsuccess varied between seasons with and without crops in the field but not between habitat types. At this site, thebreeding activity of this species is seasonal. All individuals whose stomachs were analyzed ate a wide range ofitems, indicating omnivory in this species at this site;however, seeds were the most preferred diet category, with amean contribution of 50.4%, followed by arthropods, with a mean contribution of 25.7%. Other plant materialsbecame important during the very dry periods.