Increasing browse and social complexity can improve zoo elephant welfare

While recent work has assessed how environmental and managerial changes influence elephant welfare across multiple zoos, few studies have addressed the effects of management changes within a single institution. In this paper, we examine how management changes related to social structure and diet affect the behavior of a group of zoo elephants over a 23‐month period while also considering underlying factors, such as time of day, hormonal cycle, and individual differences. We recorded individual behaviors using 2‐min scan samples during 60‐min sessions. We analyzed behavioral changes across several study variables using generalized linear mixed models. We found that increasing browse can improve opportunities for foraging throughout the day but may not be sufficient to reduce repetitive behaviors. We observed that increasing group size and integration of bulls with cows can lead to increased social interaction in African elephants. Our results highlight the importance of using multiple management alterations to address elephant welfare, and considering environmental factors, when making management decisions.     

Selecting browse plants to supplement cassava peel-based diet for peri-urban small ruminants

Cassava (Manihot esculanta) peel is routinely fed to ruminants in Ghana and most parts of Africa, but the low protein content and lack of suitable protein supplements limits its full exploitation in small ruminant production systems. This study assessed the suitability (degradation characteristics and synchrony between nitrogen release and organic matter degradation) of the leaves of three browse plants, chaya (Cnidoscolus aconitifolius), ficus (Ficus exasperata), and terminalia (Terminalia catappa), as supplements for sheep fed a cassava peel-based diet. Four ruminally fistulated Djallonké wethers were used in a randomized complete block design experiment to determine ruminal disappearance of dry matter (DM), organic matter (OM) and nitrogen (N) from the three leaves and from cassava peels. For chaya, ficus and terminalia, OM content was 93.1%, 83.8% and 90.3% (P < 0.05), respectively, whereas N was 3.4%, 3.1% and 1.7% (P < 0.05, DM basis). The OM and N content in cassava peel was 95.3% and 1.0%, respectively. Ruminal DM disappearance of chaya, ficus, terminalia and cassava peel after 24 h of incubation was 79.0%, 36.4%, 48.0%, and 43.0% (P < 0.05), respectively. The ratio of N released from chaya leaves to OM from cassava peel was 1:16 or lower during 24 h ruminal incubation, compared to 1:31 during the first 8 h and 1:25 after 12 h of incubation of ficus leaves. The ratio for terminalia leaves from 4 to 24 h of incubation ranged between 1:51 and 1:63. The high N content and ideal synchronous release of N and OM ratio of 1:33 (N:OM) made ficus leaves the most suitable supplement among the three browse leaves, with the potential to supply adequate N to optimize ruminal microbial protein synthesis in sheep on a cassava peel-based diet.     

Seeds,browse, and tooth wear: a sheep perspective

While grazing as a selective factor towards hypsodont dentition on mammals has gained a lot of attention, the importance of fruits and seeds as fallback resources for many browsing ungulates has caught much less attention. Controlled‐food experiments, by reducing the dietary range, allow for a direct quantification of the effect of each type of items separately on enamel abrasion. We present the results of a dental microwear texture analysis on 40 ewes clustered into four different controlled diets: clover alone, and then three diets composed of clover together with either barley, corn, or chestnuts. Among the seed‐eating groups, only the barley one shows higher complexity than the seed‐free group. Canonical discriminant analysis is successful at correctly classifying the majority of clover‐ and seed‐fed ewes. Although this study focuses on diets which all fall within a single dietary category (browse), the groups show variations in dental microwear textures in relation with the presence and the type of seeds. More than a matter of seed size and hardness, a high amount of kernels ingested per day is found to be correlated with high complexity on enamel molar facets. This highlights the high variability of the physical properties of the foods falling under the browsing umbrella.     

Seasonal differences between moose and roe deer in ability to digest browse

The digestive capacity of free-living moose Alces alces (L.) and roe deer Capreolus capreolus (L.) for four plant species was studied with in vitro technique. Moose were found to digest all species better than roe deer. Individual variations were also smaller for moose. In moose the level of digestibility was the same both summer and winter, while roe deer shot in winter digested winter samples of bilberry Vaccinium myrtillus L. and to some extent Scots pine Pinus silvestris L. better than did summer roe deer. This was taken as evidence for a seasonal adaptation in the roe deer rumen. Digestibility of the plant material studied showed a strong negative correlation to the fiber content. The results are discussed in relation to winter problems for roe deer and possible food competition between moose and roe deer.     

Effects of grass and browse consumption on the winter mass dynamics of elk

Much of the research into herbivore ecology and evolution has focused on patterns and mechanisms of niche partitioning in the diets of specialized grazers and browsers, but the significance of the balance of grazing and browsing within intermediate feeders present unique questions that have received less attention. We explored the nutritional effects of varying the balance of grass and browse in the winter diets of elk (Cervus elaphus). We compiled published data from three similar studies that monitored the mass dynamics of captive elk fed diets of pure grass, pure browse or 1 of 14 mixed diets in winter feeding trials. Elk lost mass (up to 22% of initial body weight) in 29 of 33 feeding trials, similar to wild elk in winter. We used regression models of mass dynamics, considering the linear, quadratic or logarithmic effects of the proportion of the diet that was grass (≈1 − proportion of the diet that was browse) and the additive and interactive effects of nitrogen intake. Diet composition had strong effects on mass dynamics, and all models explained ≥73% of the variation (adjusted r ²) in mass dynamics. Nitrogen intake had uniformly positive effects on mass balance, and increasing grass intake caused improved maintenance of body mass up to a point, but further increases in the proportion of grass in the diet had neutral or negative effects on body mass. Overall, the data suggest that elk are adapted to consuming mixed diets. Nonetheless, data on the foraging behavior and diet selection of wild elk in many populations show that elk often consume grass-dominated diets and sometimes consume browse-dominated diets, but rarely consume mixed diets. Physiological adaptations to mixed diets may place unique spatio-temporal constraints on diet selection in intermediate feeders and impose large penalties for a sub-optimal balance of grazing and browsing.     

Seasonality affects leaf nutrient and condensed tannin concentration in southern African savannah browse

Trees that maintain some leaves throughout dry seasons become important ruminant browse depending on nutritive and antinutritive values. Leaves from seven tree species that maintained some leaves during the dry season were collected during dry and wet seasons and analysed for nutritive and antinutritive values. Neutral detergent fibre of leaves was either not different or less (P ≤ 0.05) during the dry season as compared to the wet season depending on species. Acid detergent fibre was either not different or greater (P ≤ 0.05) during the dry season as compared to the wet season. Crude protein and condensed tannins (CT) were either not different or less (P ≤ 0.05) during the dry season than during the wet season for the seven species. The biological activity (protein‐binding ability; PB) of the CT was highly species specific and was either not different between seasons, more bioactive during the wet season, or more bioactive during the dry season depending on the species. Based on combinations of low fibre, high protein and potentially beneficial levels of bioactive CT, Senegalia caffra, Vachellia karoo and Searsia lancea may be the most promising dry‐season browse of the species studied.     

Composition of kermes oak browse as affected by shade and stage of maturity

Kermes oak (Quercus coccifera L.) is a sclerophyllous evergreen shrub of the Mediterranean region. In Greece, it grows either alone or in a mixture with other sclerophyllous species in shrublands or as the understory in Pinus brutia forest.The nutritive value and digestibility of kermes oak browse were investigated under 2 light conditions: an an understory species in a P. brutia forest and in adjacent open shrublands. The comparison was made at 3 phenological stages: during the season of rapid growth (in April), after rapid growth was terminated (in May) and when growth had ceased and stems had hardened (in June).Crude protein content of the leaves and twigs was higher in the shaded than in the unshaded plants during the growing season, while the concentrations of total non-structural carbohydrate, cell contents and soluble protein were higher in the unshaded than in the shaded plants. Tannins and lignin content were higher in shaded than in unshaded plants. Similarly, dry matter digestibility was higher in unshaded plants, but declined more drastically in the shaded plants during the growing season. Production was also higher in unshaded than in shaded plants at the end of the growing season.     

Moose herbivory,browse quality,and nutrient cycling in an Alaskan treeline community

Moose (Alces alces) browsing on diamondleaf willow (Salix planifolia pulchra) caused significant increases in subsequent growth of stems and leaves in treeline plant communities in central Alaska, USA. Willows growing in the shade were significantly more palatable for moose than those growing in the sun. Moose density had strong effects on rates of nutrient cycling, ostensibly through effects of browsing and inputs from fecal and urinary nitrogen. Moose are a keystone herbivore that likely mediate rates of nutrient cycling in northern ecosystems.     

Involvement of volatile compounds of Artemisia in browse preference by mule deer

Twelve collections of sagebrush, representing eight taxa at an unfenced plot near Price, Utah, were investigated to determine if the relative levels of eight major volatile compounds in the leaves influenced mule deer utilization of the various taxa during the winter. The compounds investigated were methacrolein, -pinene, camphene, β-pinene, arthole, 1,8-cineole, p-cymene, and camphor. Stepwise regression analysis indicated that one-fifth or less of the variability in utilization could be attributed to the relative percentages of the volatile constituents in the leaves. Oxygenated compounds (especially methacrolein and arthole) seemed to be more highly correlated with sagebrush utilization than hydrocarbons, and this correlation appeared to be inverse.     

Beyond the browse line: complex cascade effects mediated by white‐tailed deer

In many ecosystems, browsing of large mammals can affect plant species compositions. However, much less is known about potential above‐ and below‐ground trophic interactions of large browsing mammals. This study focused on the direct and indirect effects of browsing on trophic and abiotic interactions within forest ecosystems. To quantify above‐ and below‐ground cascade effects, white‐tailed deer have been excluded for over 18 years from three 4‐ha plots, which were paired with same sized deer access plots. Our results demonstrate complex direct and indirect cascade effects on forest food webs. Deer exclusion directly altered woody species composition and significantly increased shrub and sapling density. Above‐ground cascade effects include greater leaf litter accumulation and higher arthropod density and biomass within the exclosures. Below‐ground indirect effects include significant decrease in soil nutrients, and higher arbuscular mycorrhizal fungal inoculum potential in the exclosures. Because ecosystems have finite resource availability, high deer density may imbalance the system by redirecting resources toward maintaining deer biomass at the expense of multiple trophic levels throughout the forest community. Both complex bottom up and top down trophic cascade effects demonstrated largely unidirectional negative responses suggesting that high deer density has reduced the biodiversity of the forest community.     

The relationship between possum density and browse damage on kamahi in New Zealand forests

To minimize the impacts of introduced pests and to justify and prioritize pest control, managers need to know the relationship between pest density and damage. This relationship can be difficult to quantify because pest impacts can be highly variable. In New Zealand, introduced brushtail possums (Trichosurus vulpecula) browse a wide range of native forest species. However, possum browse is extremely patchy making it difficult to quantify the relationship between density and damage, meaning the benefits of reducing possum densities are poorly understood. We quantified patterns of possum browse on kamahi (Weinmannia racemosa), a common canopy tree species, at 21 forest sites that were repeat‐measured over an 8‐year period in the North Island, New Zealand, during which time possum densities fluctuated widely. We fitted a multilevel statistical model in order to quantify the relationship between possum density and browse damage while simultaneously quantifying how browse varied among trees, sites and years. Higher possum densities were associated with greater browse damage, but browse was also patchily distributed among trees at the same site, and among sites and years for a given possum density. This heterogeneity meant there was no simple density damage relationship, with the relationship differing from tree to tree and among sites and years. Our results show that at most sites reductions in possum density would have little benefit in reducing the probability of heavy browse on kamahi trees, but at a few sites there would be substantial benefits. This approach provides insights into the pattern and potential causes of variability in possum impacts, and a quantitative basis for prioritizing sites for possum control.     

Quercus ilex browse utilization by Caprini in Sierra de Cazorla and Segura (Spain)

The impact of domestic and wild Caprini browsing on Quercus ilex has been examined in an area of the Sierra de Cazorla. Vegetation as a herbivore food supply, herbivore feeding regime and density in the study area during six sampling periods throughout two years, has been quantified. Wild Caprini show diets similar to the available vegetation, whereas domestic Caprini tend more towards the trophic specialities (browsing or grazing) of their genus. Nevertheless, this tendency was more pronounced in domestic goats than in sheep. A hypothetical estimate of Q. ilex intake by each species under the study conditions was carried out. It was found that domestic Caprini have a greater impact on the holm oak than wild Caprini, density and feeding-niche deviations being the main factors responsible for this situation.Abbreviations DM= dry matter     

Sapling growth responses to warmer temperatures ‘cooled’ by browse pressure

Rising temperatures are predicted to cause temperate tree species to expand north into currently boreal dominated forests. Other factors, such as overabundant deer, may hinder temperate expansion. We examined how interactions among temperature, browse pressure, light availability, and initial size impact height and radial growth of naturally regenerated, competing temperate and boreal saplings across their overlapping range limits in central North America. In 9 of 10 growth model comparisons, the inclusion of mean summer temperature and browse damage as explanatory variables strongly improved model performance over the base model with only initial size and light availability as parameters. Potential growth reductions due to browse damage and temperature limitation were similar in magnitude (up to ~50%). Temperate sapling growth increased and boreal growth decreased with temperature across a regional summer temperature gradient (2.3 °C), causing a rank reversal in growth rates, and suggesting that temperature is a key driver of sapling performance and range boundaries. However, under high browse pressure positive temperate responses to temperature were eliminated, essentially pushing the crossover point in growth between temperate and boreal species further south. These results highlight the importance of interactions among global change agents and potential impediments for tree species to track a rapidly changing climate.     

Analyses of African elephant (Loxodonta africana) diet with various browse and pellet inclusion levels

To more closely simulate the diet of free-ranging elephants, the diet of six (2.4) African elephants (Loxodonta africana) was altered to include more browse and less pelleted complete feed (5% total diet). Dietary proximate compounds, minerals, vitamins A (and carotenoids), D and E, and fatty acids were analyzed on pelleted diet items and forages including hay, grass, and browse. A total of 42 browse species were offered over 1 year with an average total diet inclusion of 5.2% (dry matter basis) per day. Dietary Na and Se were low while Fe and Mn were high compared to published intake levels for elephants. Analyzed nutrients within browse varied widely among seasons and species. Ingredient analyses were used to create predicted elephant nutrient intake for (a) the current diet, (b) a diet excluding pellets, and (c) a diet excluding pellets and providing browse at doubled levels. Formulated diets excluding pellets had lower mineral levels than the current diet and doubled browse did not alter mineral inclusions of concern. This study provides seasonal data on the nutrient levels of Southeastern browse species important for various pachyderm and herbivorous species. Predicted nutrient intake with new diet scenarios does not support the exclusion of pellets in the diets of African elephants without greater browse quantity availability, strict diet management, or additional supplements.     

Terpene production and growth of three Pacific Northwest conifers in response to simulated browse and nutrient availability

Natural variation in ungulate browsing behavior interferes with the understanding of plant morphological and biochemical responses to herbivory. To investigate mechanisms for recovery from herbivory, we examined growth patterns and biosynthesis of terpenoids under simulated browse (three clipping intensities) and supplemental mineral nutrition (four levels of controlled-release fertilization) for Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco], western hemlock (Tsuga heterophylla Raf. Sarg.), and western red-cedar (Thuja plicata Donn ex D. Don) seedlings on a reforestation site in Northwestern Oregon, USA, that was fenced to exclude ungulates. Higher clipping intensities increased relative height growth (at cost of diameter growth) for all the species. Only western red-cedar showed a decline in monoterpene concentrations with increasing clipping severity, suggesting prioritization in biosynthesis of terpenoids for this species. Douglas-fir and western hemlock responded to fertilization mostly through increased growth. Western red-cedar growth responses to fertilization were less pronounced, but monoterpene concentrations were 2–3 times higher compared to non-fertilized trees. Douglas-fir and western hemlock browse recovery and responses to fertilization consisted primarily of increased growth, while western red-cedar balanced growth promotion with production of chemical defense compounds. Our data suggests the evolution of species-dependent resource allocation strategies in response to both browse and soil nutrient availability.     

Seasonal variations in the quality of mopane leaves as a source of browse for mammalian herbivores

This paper deals with seasonal variations in the chemical composition of mopane leaves in terms of their palatability to herbivores. Green mopane leaves were found to be most palatable over summer, a period when, due to very poor rainfall, the veld was at its most desolate. Senescing leaves were at their most palatable in late winter/early spring, this resource maintaining many herbivores for the short period before the spring leaf flush. Four leaf classes were identified during the spring leaf flush: young green leaves were the most palatable followed by very young leaves, mature green leaves and senescent leaves. The flush is independent of rain and coincides with the end of the dry season, a period when most tree species occurring in association with the mopane are leafless and the grass sward is very poor. It begins earlier on heavily browsed trees. Most ungulates present in the area were found to utilize the nutritious young leaves. The importance of this leaf flush is discussed with respect to the management of the area, and the importance of the heavy pressure large mammals are imposing on this veld type is elicited.