Annual Diet Research Articles

Cohort profile: the CARTaGENE Cohort Nutrition Study (Quebec, Canada)

PurposeTo address emerging nutritional epidemiological research questions, data from contemporary cohorts are needed. CARTaGENE is the largest ongoing prospective cohort study of men and women in Québec, Canada. Dietary information...

Dental microwear analysis of Kudaro cave bears: Insights into dietary evolution from the Middle to Late Pleistocene

The dietary changes of early cave bear populations from the Middle to Late Pleistocene are poorly understood. In this study, we analysed 60 m1 through dental microwear analysis of three diachronic Middle (Ursus praekudarensis and U. praekudarensis/kudarensis) to Late Pleistocene (U. kudarensis) populations inhabiting the Kudaro 1 and Kudaro 3 caves in the Southern Caucasus. The diet of all populations was inferred to be omnivorous, although it changed over time, adapting to the climatic and ecological conditions of the period. Bones from U. praekudarensis/kudarensis populations accumulated throughout the year; thus, microwear suggests an average annual diet dominated by plant resources. The widespread presence of hypercoarse scratches in U. kudarensis and U. praekudarensis populations suggests animal protein intake during the hyperphagia. The presence of omnivorous guild competitors and harsh conditions in a high-altitude environment could have driven the Caucasian cave bears to consume animal protein as a fallback diet during their predormancy period. Furthermore, the cave bears' capacity for dietary flexibility through time highlights the ability of cave bears to withstand climatic changes, while competition with other omnivorous species could have driven their dietary niche during their hyperphagia period towards animal protein consumption throughout the Middle to Late Pleistocene.

Effects of Habitat and Fruit Scent on the Interactions between Short-tailed Fruit Bats and Piper Plants.

Piper is a mega-diverse genus of pioneer plants that contributes to the maintenance and regeneration of tropical forests. In the Neotropics, Carollia bats use olfaction to forage for Piper fruit and are a main disperser of Piper seeds via consumption and subsequent defecation during flight. In return, Piper fruits provide essential nutrients for Carollia year-round. There is evidence that the types and diversity of Piper frugivores are influenced by the primary habitat type of different Piper species (forest and gap), with forest Piper depending more on bats for seed dispersal; however, this pattern has not been tested broadly. We aimed to characterize and compare the interactions between Carollia and Piper across forested and gap habitats, and further investigate whether differences in fruit traits relevant to bat foraging (i.e., scent) could underlie differences in Carollia-Piper interactions. We collected nightly acoustic ultrasonic recordings and 24 h camera trap data in La Selva, Costa Rica across 12 species of Piper (six forest, six gap) and integrated this information with data on Carollia diet and Piper fruit scent. Merging biomonitoring modalities allowed us to characterize ecological interactions in a hierarchical manner: from general activity and presence of bats, to visitations and inspections of plants, to acquisition and consumption of fruits. We found significant differences in Carollia-Piper interactions between forested and gap habitats; however, the type of biomonitoring modality (camera trap, acoustics, diet) influenced our ability to detect these differences. Forest Piper were exclusively visited by bats, whereas gap Piper had a more diverse suite of frugivores; the annual diet of Carollia, however, is dominated by gap Piper since these plants produce fruit year-round. We found evidence that fruit scent composition significantly differs between forest and gap Piper, which highlights the possibility that bats could be using chemical cues to differentially forage for gap vs. forest Piper. By integrating studies of Piper fruit scent, plant visitation patterns, and Carollia diet composition, we paint a clearer picture of the ecological interactions between Piper and Carollia, and plant-animal mutualisms more generally.

Spatial distribution and diet of Lake Michigan juvenile lake trout

Most studies of Lake Michigan lake trout (Salvelinus namaycush) have focused on adults, with scant attention to juveniles (<400 mm). We explored the spatial distribution and diet of juvenile lake trout using U.S. Geological Survey September bottom trawl data (2015–2022) and stomach content information opportunistically collected since 2012 by various agencies using multiple gear types. Most juvenile lake trout in the September bottom trawl survey were caught at 37–64 m bottom depths. Length frequency data from the bottom trawl survey identified three size classes likely associated with wild juvenile lake trout age: < 85 mm (∼age-0), 85–170 mm (∼age-1) and > 170 mm (∼age-2+). Largest catches of wild lake trout < 170 mm occurred along a northeastern transect (near Frankfort, Michigan), whereas most > 170 mm were collected along southern transects. Mysis diluviana was the dominant prey for juvenile lake trout < 170 mm, and > 250 mm were primarily piscivorous, while 170–250 mm appeared to be a transitional period of switching from Mysis to fish. Species composition of prey fishes consumed by lake trout varied spatially and we found evidence of seasonal and annual diet variation within Grand Traverse Bay. Diporeia, once an important component of juvenile lake trout diet, appears to no longer be consumed by juvenile lake trout in Lake Michigan to any measurable degree. Continued research on the ecology of juvenile lake trout may provide insight into the effects of a changing ecosystem on juvenile lake trout diet and growth, thereby contributing to the effort to rehabilitate the Lake Michigan lake trout population.

Quantified diet provides suggestions for habitat restoration for the world's rarest primate

Habitat restoration for endangered species requires sufficient understanding of species' feeding ecology. Hainan gibbon (Nomascus hainanus) is the world's rarest primate species, with only one population of ca. 40 individuals living in Bawangling, Hainan Province, China. Limited habitat is the main factor restricting its population recovery. Previous studies suggested Hainan gibbons live in suboptimal habitats and recommended Lauraceae for habitat restoration. From September 2021 to December 2022, we used 5-min interval scans sampling method to collect quantitative data of feeding behavior of two Hainan gibbon groups. We totally tracked gibbons for 1477 h over 216 observation days and collected 17,249 feeding behavioral records. As a result, the two gibbon groups were observed to consume 146 plant species from 111 genera, 65 families. Fruits and figs from average 79 plant species contribute 85.36 % to the annual diet of each group. The larger number and higher proportion of fruit species in the annual diet comparing to those of other gibbon populations indicate that the habitat quality of extant Hainan gibbons is not as poor as previously thought. Meanwhile, species of Lauraceae are abundant in the habitat but contributed little to the gibbon's diet, thus should not be recommended for habitat restoration. We utilized four quantified indexes to filter three important food species lists, which can be reliable references for plant selection in habitat restoration. By clarifying these crucial misunderstandings and providing species lists for habitat restoration, our work again emphasizes the importance of quantified diet on habitat restoration for endangered species.

Feeding ecology of a highland population of hamadryas baboons (Papio hamadryas) at Borena-Sayint National Park, northern Ethiopia.

Studying the diet and feeding behavior of primates is essential to understanding their ecology and designing effective conservation plans. Despite decades of study on the hamadryas baboon (Papio hamadryas) in lowland habitats, little is known about the feeding ecology of this species in highland ecosystems. To address this empirical gap, we tracked temporal changes in vegetation abundance and their relation to the dietary choices of hamadryas baboons in highland habitat at Borena-Sayint National Park (BSNP) in northern Ethiopia. We performed behavioral scan sampling on a focal study band of 21-37 hamadryas baboons over a 12-month period. We found that mature and young leaves were the most abundant plant parts throughout the year, while fruits and flowers were the least abundant, with significant seasonal variation that followed the bimodal pattern of rainfall characteristic of the Ethiopian highlands ecosystem. The annual diet of hamadryas baboons at BSNP consisted mostly of fruits (32.0%) and graminoid blades (21.2%), and included 52 food species across 22 families of plants and three families of animals. Food raided from nearby farms accounted for 8.8% of their diet. The availability of fruits and flowers was positively correlated with their consumption, suggesting that these are preferred foods, whereas graminoid blades, and other leaves, appeared to be less preferred foods. The feeding ecology of hamadryas baboons at BSNP differs considerably from that of lowland populations. The well-studied lowland hamadryas baboons in Awash National Park obtain much of their diet from Acacia species and palm fruit, whereas those at BSNP, where Acacia trees are rare and palms are absent, relied on Olinia rochetiana and Rosa abyssinica for a combined 27% of their annual diet. The reliance of hamadryas baboons at BSNP on cultivated crops for nearly one-tenth of their diet leads to conflict with humans and warrants more detailed study so that this issue can be addressed in conservation plans for the area.

Feeding ecology of the vulnerable aoudad (Ammotragus lervia) in north‐western Sahara

AbstractThe feeding ecology of the aoudad (Ammotragus lervia) was investigated for the first time in north‐western Sahara, Djebel Antar (Bechar province, Algeria), from autumn 2015 to summer 2016. Microhistological analyses of faeces revealed an annual diet composed of 23 identified taxa belonging to 16 plant families. The highest species diversity was recorded in spring and summer (23 species), despite a marked consumption of two species: Vachellia tortilis (17.7%) and Avena sterilis (14.0%); diet diversity was lower in autumn and winter (16 species), including mainly Teucrium polium (14.7%, 21.0%) and Gymnocarpos decander (19.7%, 10.0%). The main plant parts consumed during these seasons were stems (77.7%, 65.3%), while leaves and inflorescences were mostly consumed during spring and summer (54.7%, 52.3%). Forbs dominated the aoudad's diet, with 46.3% average relative abundance, including mainly T. polium, Limoniastrum feei, and Chrysanthemum macrocarpum. Woody plants including mainly V. tortilis and G. decander accounted for 33.3% (50.0% in autumn), and grasses including A. sterilis and H. murinum for 20.4% (32.0% in summer). Based on this diet, A. lervia can be classified as a “generalist mixed‐feeder.”

Relative abundance, habitat selection, and diet of the coyote in northern México

The coyote (Canis latrans) is a widespread predator with a high degree of adaptation to different ecosystems. The objective of this study was to estimate the relative abundance index, habitat selection, and diet of C. latrans through scent stations, in two types of vegetation located in northwestern Chihuahua. From April 2018 to March 2019, ten fixed scent stations (SS) were placed in pine-oak forest and other ten in semi-open grassland, with a linear separation of 500 meters between each station to achieve a five km transect in each vegetation during 12 samplings (two sampling night per month) for totaling 420 SS after discarding inactive SS. The relative abundance index of coyote showed that both types of vegetation, pine-oak forest (0.30) and semi-open grassland (0.23) were used in a similar way. The habitat selection test (Chi2) showed that coyote abundance and type of vegetation were independent (χ2 = 2.96, P &gt; 0.05), not showing statistically significant differences in annual relative abundance index of coyotes between the two vegetation types. The food items detected in thirty-four scats collected belonged to mammals (55.9 %), fruits (35.3 %) and arthropods (8.8 %). Rodents and lagomorphs were the main source of food. Throughout the sampling period, the pine-oak forest showed the greatest relative abundance index of C. latrans. This may be because the forest provides them with shelter from climatic situations and a greater variety of seeds, fruits and insects. In this study the two seasons with the highest relative abundance were spring and autumn in both ecosystems, coinciding with an increase in rainfall, resulting in an abundance of potential prey (rodents and lagomorphs), and other food items like fruits. Regarding annual diet the most consumed prey were mammals. We found differences in diet between seasons, that can be explained by the variation in food availability among seasons.

Diet shifting of tortoise-eating Golden Eagles (Aquila chrysaetos) in southeastern Bulgaria

Top predators may adapt their diets to changes in prey availability where human-induced environmental changes are intense. This long-term study of the breeding-season diet of Golden Eagle (Aquila chrysaetos) in the Strandzha Mountains analyzed shifts in diet caused by the population decline in principal prey species, the tortoises (Testudo hermanni and T. graeca). Tortoises comprised 50.0% of the eagle diet by prey number in the 1990s, but that share collapsed to 5.8% in 2014–2021. During this later interval, Golden Eagles preyed more intensively on lighter-weight prey such as Northern White-breasted Hedgehog (Erinaceus roumanicus, an increrase of 28.2% by number) and Edible Dormouse (Glis glis, an increase of 14.9% by number). Hedgehogs predominated in the diet of an individual eagle nest site for the first time in 1998 and became the principal prey in 2014–2021. Differences in food niche breadth and proportions of mesopredators between tortoise- and hedgehog-dominated individual annual diets were not significant, corresponding to a low level of food stress. The only eagle with an annual diet dominated by Squamata (snakes and lizards) was an exception, having the widest food niche. Young domestic ungulates have almost completely disappeared from eagle diets at the same as the reduction of tortoises, corresponding to a concurrent decline of livestock farming. The results obtained here have relevance to conservation management of both predator and prey populations.

Effects of food availability and its seasonal changes on the dietary habits of wild silvery lutungs (Trachypithecus cristatus) in a coastal forest in west Sumatra, Indonesia

Abstract The dietary composition of primates is often affected by the availability of food, as well as seasonal variations within their habitat. This study presents quantitative data on the feeding behavior of wild silvery lutungs (Trachypithecus cristatus) inhabiting a coastal forest in West Sumatra, Indonesia. This research emphasizes the relationship between food availability and the way this changes by season. Feeding strategies of these primates was also examined. Feeding behavior of a group of wild silvery lutungs was observed for 12 months from August 2018 to July 2019, with a total observation time of 482 hours. We recorded 74 items from 37 different plant species that were included in the lutungs’ diet. Nineteen out of 37 plant species comprised &gt; 1% of the lutung’s annual diet. They can therefore be considered the main plant food sources for the lutungs. The lutungs mainly fed on young leaves (68.3%). However, during certain months, both ripe and unripe fruit formed a major part of their diet. Plant part-based analyses showed a negative correlation between the availability of young leaves and ripe fruit feeding. Plant species-based analyses revealed few significant positive relationships between the feeding percentages of the main dietary items (mainly young leaves) and their availability. This implies that young leaves and ripe fruit were both the preferred and the fallback foods. This also indicates that lutung activity, ranging patterns, and activity at the study site are affected mainly by food distribution and availability. Further research is needed to increase the understanding of Asian colobine feeding strategies, feeding patterns, and food resource characteristics.

Trophic niche overlap between coyotes and gray foxes in a temperate forest in Durango, Mexico.

Resource partitioning, and especially dietary partitioning, is a mechanism that has been studied for several canid species as a means to understand competitive relationships and the ability of these species to coexist. Coyotes (Canis latrans) and gray foxes (Urocyon cinereoargenteus) are two canid species that are widely distributed, in Mexico, and they are sympatric throughout most of their distribution range. However, trophic dynamic and overlap between them have not been thoroughly studied. In order to better understand their ecological relationship and potential competitive interactions, we studied the trophic niche overlap between both canids in a temperate forest of Durango, Mexico. The results are based on the analysis of 540 coyote and 307 gray fox feces collected in 2018. Both species consumed a similar range of food items, but the coyote consumed large species while the gray fox did not. For both species, the most frequently consumed food categories throughout the year and seasonally were fruit and wild mammals (mainly rodents and lagomorphs). Coyotes had higher trophic diversity in their annual diet (H' = 2.33) than gray foxes (H' = 1.80). When analyzing diets by season, trophic diversity of both species was higher in winter and spring and tended to decrease in summer and autumn. When comparing between species, this parameter differed significantly during all seasons except for summer. Trophic overlap throughout the year was high (R0 = 0.934), with seasonal variation between R0 = 0.821 (autumn) and R0 = 0.945 (spring). Both species based their diet on the most available food items throughout each season of the year, having high dietary overlap which likely can lead to intense exploitative competition processes. However, differences in trophic diversity caused by differential prey use can mitigate competitive interactions, allowing these different sized canid species to coexist in the study area.

Seasonal diet composition of Himalayan goral (Naemorhedus goral) in Kajinag National Park, Jammu and Kashmir, India

Abstract In temperate environments, forage availability and quality are known to influence life history traits of wild ungulates. However, variations in foraging strategies of these mountain dwellers with changing plant availability have received little attention. The seasonal vegetation availability in temperate climatic conditions of Kajinag National Park (KNP) was assessed by plot method at different altitudes (1900–3600 m a.s.l.) from 2018 to 2020 on seasonal basis. The objective of this study was to determine the impact of availability of vegetation on seasonal diet composition of Himalayan goral (Naemorhedus goral) inhabiting the National Park. We recorded 61 plant species whose availability differed significantly across seasons (F 3,240 = 20.14, p &lt; 0.05). We found seasonal variation in the diet composition of Himalayan goral depicting a strong relationship between plant consumption and dynamic availability in the study area. Himalayan goral consumed herbs in spring (dominated by Dioscorea deltoidea relative importance value (RIV) = 27.20, Poa pratensis RIV = 14.99 and Themeda spp. RIV = 12.87), grasses in summer (dominated by Themeda spp. RIV = 34.12, P. pratensis RIV = 30.14, Bothriochloa ischaemum RIV = 22.72) and autumn (dominated by Themeda spp. RIV = 34.64, P. pratensis RIV = 30.14, Stipa spp. RIV = 29.73) and shrubs in winter (dominated by Indigofera heterantha RIV = 47.05, Prunus tomentosa RIV = 17.51 and Lonicera spp. RIV = 16.98). The annual diet of Himalayan goral was dominated by graze species (72.66%). The proportion of graze items in the diet showed a sharp decline from spring (90.67%) to winter (19.23%) whereas that of browse showed a huge increment from spring (4.67%) to winter (74.43%). This shift shows a survival or foraging strategy of a temperate ungulate in harsh winters with limited forage availability.

Seasonal paleoecological records from antler collagen δ13C and δ15N

AbstractCervids living in high latitudes have evolved to thrive in ecosystems that experience dramatic seasonal changes. Understanding these seasonal adaptations is important for reconstructing cervid life histories, ecosystem dynamics, and responses in the distant and not-so-distant past to changing seasonality caused by climate change. Cervid antlers provide a rare opportunity for insight into faunal seasonal ecology, as they are grown and shed each year. Stable isotopes of carbon and nitrogen measured directly from antlers have the potential to provide seasonal dietary data for individuals. If the isotopic signals in bone and antler are controlled by the same metabolic processes, then the stable carbon and nitrogen isotope compositions of collagen (δ13CColland δ15NColl) from incrementally grown antler tissue provide time-constrained dietary signals from the spring and summer growth season. Bone, by comparison, provides an average signal over several years. The amino acid (glutamate and phenylalanine) δ15N in antlers from modern captive caribou showed similar trophic discrimination factors to earlier results for other collagenous tissues (bone, tooth dentin, and cementum). Hence, growth rate was not the primary control on the stable isotope composition of antler collagen. We applied this knowledge to assess seasonal shifts in Quaternary fossils of three Cervidae species: elk (Cervus elaphus), moose (Alces alces), and caribou (Rangifer tarandus). Paired antler–bone δ13CColland δ15NCollfrom the same individual were used to identify differences between summer and annual diet and ecology. Intra-antler isotopic variability from serially sampled antlers was used to examine seasonal dietary shifts and specialization.

Fermented food consumption in wild nonhuman primates and its ecological drivers.

Although fermented food use is ubiquitous in humans, the ecological and evolutionary factors contributing to its emergence are unclear. Here we investigated the ecological contexts surrounding the consumption of fruits in the late stages of fermentation by wild primates to provide insight into its adaptive function. We hypothesized that climate, socioecological traits, and habitat patch size would influence the occurrence of this behavior due to effects on the environmental prevalence of late-stage fermented foods, the ability of primates to detect them, and potential nutritional benefits. We compiled data from field studies lasting at least 9 months to describe the contexts in which primates were observed consuming fruits in the late stages of fermentation. Using generalized linear mixed-effects models, we assessed the effects of 18 predictor variables on the occurrence of fermented food use in primates. Late-stage fermented foods were consumed by a wide taxonomic breadth of primates. However, they generally made up 0.01%-3% of the annual diet and were limited to a subset of fruit species, many of which are reported to have mechanical and chemical defenses against herbivores when not fermented. Additionally, late-stage fermented food consumption was best predicted by climate and habitat patch size. It was more likely to occur in larger habitat patches with lower annual mean rainfall and higher annual mean maximum temperatures. We posit that primates capitalize on the natural fermentation of some fruits as part of a nutritional strategy to maximize periods of fruit exploitation and/or access a wider range of plant species. We speculate that these factors contributed to the evolutionary emergence of the human propensity for fermented foods.

Diet and Activity Budget in Colobus angolensis ruwenzorii at Nabugabo, Uganda: Are They Energy Maximizers?

Introduction: Colobine monkeys are specialized folivores that use foregut fermentation to digest leaves. The slow process of fermentation forces them to spend a lot of time resting and to minimize their energy expenditure to subsist on a lower-quality diet. Methods: We recorded the diet and activity budget of Colobus angolensis ruwenzorii, which form a three-tiered multi-level society, at Lake Nabugabo, Uganda, over 12 months using scan sampling on adults and subadults, to determine whether they utilize the energy minimization strategy typical of colobines. Results: We found that the annual diet was primarily comprised of high-quality food resources (young leaves 65% and fruit 31%), and fruits were the only plant part the monkeysselected when available. Both the fruits and young leaves of some species were preferred food items in some months, and mature leaf consumption correlated negatively with preferred food availability. Mature leaves appear to be a fallback food for this population but are rarely relied upon (3%). The C. a. ruwenzoriiat Nabugabo spent less time resting (40%) and more time moving (25%) than is typical for other species of black-and-white colobus. Discussion/Conclusion: The high-quality diet of this population appears to allow them to utilize an energy maximization strategy. Their reliance on food items that tend to be clumped in space and time likely explains the frequent fission-fusion behaviour that we observe between core units. Our findings demonstrate that the foraging strategies of colobines may be more flexible than was previously thought and illustrate how food availability and distribution can impact primate social organization.

Timing of dietary switching by savannah elephants in relation to crop consumption

Tree and grass quality on the African savannah shows seasonal variation, driving mixed-feeding herbivores to switch between browsing and grazing. During this switch, crop consumption could be an attractive alternative to browsing. We analysed elephant diet variability in the Okavango Delta, Botswana, using faecal stable isotope ratios of carbon (δ^13C) and frequencies of elephant crop consumption, to determine the extent to which crop consumption relates to this potential switch. Although elephants did increase their relative grass consumption in the wet season, browse dominated the annual diet. After February, the proportion of grass in the diet dropped considerably, and continued decreasing through April when farmers reported most crop consumption. Generalized Linear Models revealed that the occurrence of elephant crop consumption increased with the proportion of grass consumed and with decreasing grass quality. The proportion of grass in elephant faeces increased with increasing crop consumption intensity. As crop consumption could also be related to nutrient deficiencies in elephant diet, we calculated the total dietary input of nutrients to reveal potential deficiencies. Elephant diet contained insufficient levels of sodium year-round, and insufficient phosphorus from February to July. As the latter coincides with the timing of crop consumption, we consider our results an indication that phosphorus –and potentially sodium - deficiencies, could play a role in elephant dietary choices, including crop consuming behaviour. Further experimental research is required to show whether supplying elephants with supplementary phosphorus and sodium sources could reduce this micro-nutrient deficiency, and could play a role in reducing elephant crop consumption.

Feeding of European Pilchard, Sardina pilchardus (Walbaum, 1792) in Derna Coast, Eastern Libya

A total of 700 specimens of Sardina pilchardus were collected monthly from the catch of trawling net and lampara fishery operating on the Derna coast on the Mediterranean Sea from August to July 2018. The feeding habits including the annual diet composition, monthly variations in the diet composition, and the variations of the diet with length, and the intensity of feeding were studied. Sardinella pilchardus feed on a wide variety of prey types: copepods (37.9%), cladocerans (22.0%), polychaete larvae (17.0%), dinoflagellates (14.1%), diatoms (5.2%), and crustaceans eggs (3.9%). Copepods and cladocerans were the major food item all year round (59.9%) and it was found in all length groups. In the present study copepods, cladocerans, polychaeta larvae, and crustacean eggs increased as the size increased while diatoms and dinoflagellates decreased as the fish size increased. The feeding intensity was quite high during the autumn (72.9%), summer (74.7%), and spring (60.7%).

Asymmetric competition between sympatric endangered primates affects their population recovery

Species interactions including predation, competition, and parasitism, matter to species conservation. Sympatric species can have a profound influence on the population recovery of endangered species through a number of ecological processes, but particularly feeding competition. We investigated ranging (spatial pattern) and feeding (trophic overlap) behavior of sympatric critically endangered western black crested gibbons (Nomascus concolor) and endangered Indochinese gray langurs (Trachypithecus crepusculus). Our 1-year study of one group of each species found potential for asymmetric feeding competition between langurs and gibbons on Mt. Wuliang, China, in that: (1) the home range (2 km2) of the gibbon group was nearly entirely within the home range of the langur group (4.2 km2); (2) langurs had a greater niche breadth than gibbons, and their trophic overlap was 0.23; (3) 14 out of 26 primary food items comprising 56.7% of gibbon annual diet were consumed by langurs; and (4) langurs routinely consumed unripe fruits before they ripened sufficiently for gibbons to eat. Differences in group size, feeding habits, and reproductive rate could increase the effects of asymmetric dietary in potential competition, which appears to limit population recovery of gibbons. Rapid recovery of one species may cause unintended conservation consequences through complex interspecific interaction. Thus, it is important that conservation strategies take species interactions into account when designing conservation interventions. To ensure the ongoing survival of gibbons it may be necessary to manage langur populations.

Diet of the marsh deer in the Paraná River Delta, Argentina—a vulnerable species in an intensive forestry landscape

The marsh deer (Blastocerus dichotomus) is the largest deer native to South America, occurring in wetlands and marshy habitats. The southernmost population of the species is found in the Parana River Delta, Argentina, in a wetland system highly modified by intensive forestry activity. Foresters perceive high levels of economic losses attributed to deer herbivory which drives marsh deer poaching. We carried out the first study of the dietary composition of the marsh deer in this wetland by using microhistological analysis of feces collected seasonally. Seventy-three food items were identified in the marsh deer diet, but only eight had frequencies of > 3% in the annual diet. Macrophytes dominated the diet throughout the year (seasonal percent frequencies 31–42%) due to the high occurrence of Ludwigia bonariensis (24% of average seasonal frequency). Trees, vines, forbs, and shrubs contributed less frequently to the diet, while grasses and grass-like plants were marginally represented (i.e., < 2%). Exotic plant species comprised 38% of the annual diet, and tree species of commercial importance (Salix sp. and Populus R22) were poorly represented (≤ 5.5% per season). The marsh deer in this wetland could be categorized as a browser, differing from the feeding behavior reported for the species in the Brazilian Pantanal (grazer–browser) and suggesting a trophic elasticity in this cervid. Since commercial tree species comprised a very small portion of the diet of this deer, a change in producers’ perception toward the species is needed to diminish this conflict, and our data are important to develop context-specific conservation and management solutions.

A quantitative case study assessment of biophysical and economic effects from altering season of calving in temperate pasture-based dairy systems

In theory, a late winter-early spring calving date in temperate grazing systems best matches pasture supply and herd demand, thereby minimizing the need for nonpasture feeds and maximizing profitability. We used a quantitative case study approach to define the effects of season of calving on biophysical and financial performance in a grazing system without the confounding effects of imported feeds (i.e., milk production directly from grazed pasture). A 2-yr production system experiment was established to quantify the effects of changing onset of seasonal calving (i.e., planned start of calving; PSC) from winter (July in the Southern Hemisphere) to spring (October), summer, (January), or autumn (April) on pasture and animal production and profitability. Eighty Holstein-Friesian cows were randomly allocated to 1 of 4 PSC treatments, each of which had a different PSC [mean calving date of January 10 (JAN), April 10 (APR), July 10 (JUL), or October 10 (OCT)]. Data were analyzed for consistency of treatment response over years using ANOVA procedures with year, PSC treatment, and year × PSC treatment interactions as fixed effects. Collated biological data and financial data extracted from a national economic database were used as fixed variables to model the financial performance for the different treatments. A stochastic risk analysis was undertaken, where historical pasture growth and milk price data were used to estimate the probability distributions for stochastic input variables. Gross farm revenue and operating profit per hectare were modeled under 2 scenarios: (A) milk price did not include a premium for milk supplied during the winter, and (B) milk price included a realistic premium for milk supplied in winter. Annual and seasonal pasture growth did not differ between treatments, but the pasture growth (kg of dry matter/ha) and profile of the JUL treatment best matched the lactation nutrient demand profile. In comparison, profiles for JAN, APR, and OCT calving treatments had periods of greater surplus and deficit due to the time of calving and herd demand relative to the pasture growth profile. As a result, the JAN and OCT treatments conserved more pasture as silage and cows consumed a larger proportion of their annual diet as silage. Although the amount of silage conserved and consumed did not differ between the JUL and APR calving treatments, the timing of the silage consumption was different, with silage making up a greater proportion of the diets in the APR treatment 1 to 90 and 91 to 180 d postcalving and being offered to the JUL calving treatment only 271 to 365 d postcalving. As a result of differences in the quantity and proportion of pasture and pasture silage in the lactating diet, the JUL treatment herd tended to produce greater milk, 4% fat-corrected milk, fat, protein, and lactose yields (kg/cow) than the other PSC treatments, which did not differ from each other. Operating expenses per hectare did not differ materially between calving date scenarios, but operating expenses per kilogram of fat-corrected milk and kilogram of fat and protein were 15 to 20% less in the JUL treatment. With or without a realistic winter milk premium, gross farm revenue and operating profit per hectare were greater in the JUL treatment than in the APR treatment, which had greater revenue and profitability than the remaining 2 calving date treatments. In summary, our results indicate that a PSC in late winter is most profitable in a grazing system not importing feed, with or without a realistic price incentive scheme.