Giant pandas exhibit seasonal changes in bamboo plant part preference. The influences on the gastrointestinal tracts (GIT) microbial populations were evaluated during a 14-month period for a pair of adult male and female giant pandas housed at the Memphis Zoo using traditional culturing methods to enumerate eight bacterial groups (total anaerobes, total aerobes (TAR), streptococci (STR), total enterics, Escherichia coli, Bacteroides spp., lactobacilli and Clostridium spp.). Both the male and female pandas altered bamboo consumption behaviours, with a sharp decrease in leaf preference in April 2010 and returning to high levels of leaf preference from June to October, corresponding to significant shifts in the densities of TAR, STR, and lactobacilli and Bacteroides spp. These findings indicate seasonal changes in food preference affect the assemblages of microbial populations within the GIT of the giant panda and contribute to a better understanding of the importance of bamboo in this species' foraging strategy.

Corticosterone plays a central role in maintaining homeostasis, promoting energy acquisition, and regulating the stress response in birds. Exposure to elevated levels of corticosterone during development can profoundly alter offspring behaviour and physiology, but the effects of elevated maternal corticosterone on offspring development remain poorly understood.We tested two competing hypotheses concerning the effect of maternally derived corticosterone on growth and development of free-living house wrens: (i) elevated maternal corticosterone causes damaging effects on nestling phenotype and fitness (collateral damage hypothesis) and (ii) increased maternal corticosterone enhances offspring fitness by preparing nestlings for the environment experienced by their mother (environmental/maternal-matching hypothesis).We used a non-invasive means to increase maternal corticosterone by providing females with corticosterone-injected mealworms prior to and during egg production in the absence of any overt pre-natal maternal stress. To disentangle pre- and post-natal effects of this elevation in maternal corticosterone, we cross-fostered young in two experiments: (i) nestlings of control and experimental females were reared by unmanipulated, natural females in a uniform maternal environment; (ii) a split-brood design that enabled us to assess the interaction between the mother’s corticosterone treatment and that of the nestlings.There were significant pre-natal effects of increased maternal corticosterone on nestling growth and survival. Offspring of females experiencing experimentally increased corticosterone were heavier and larger than offspring of control females. There also was a significant interaction between maternal corticosterone treatment and the corticosterone treatment to which young were exposed within the egg in their effect on nestling survival while in the nest; experimental young exhibited greater survival than control young, but only when reared by control mothers. There was also a significant effect of maternal corticosterone treatment on nestling stress reactivity and, in both experiments, on the eventual recruitment of offspring as breeding adults in the local population.These patterns are broadly consistent with the environmental/maternal-matching hypothesis, and highlight the importance of disentangling pre- and post-natal effects of manipulations of maternal hormone levels on offspring phenotype.

Seasonal changes in the foodscape force herbivores to select different plant species or plant parts to meet nutritional requirements. We examined whether the search for calorie-rich carbohydrates explained giant panda’s selection for bamboo culm over leaves during spring. Leaves and culms were collected from four Phyllostachys bamboos (P. aurea, P. aureosulcata, P. glauca, and P. nuda) once per month over 18–27 months. Monthly changes in annual plant part nutrients were examined, and compared to seasonal foraging behaviors of captive giant pandas. Although total fiber was greater (p<0.0001) in culm (85.6 ± 0.5%) than leaves (55.3 ± 0.4%) throughout the year, culm fiber was at its lowest in spring (79–85%) when culm selection by giant pandas exceeded 70% of their overall diet. Culm starch also was greatest (p = 0.044) during spring (5.5 ± 1.1%) and 2.5-fold the percentage of starch in leaves (2.2 ± 0.6%). The free sugars in spring culm consisted of a high proportion of glucose (35%) and fructose (47%), whereas sucrose made up 42% of the total free sugar content of spring leaves. Bound sugars in culm consisted of 60% glucose and 38% xylose likely representative of hemicellulose. The concentrations of bound sugars (hemicelluloses) in spring culms (543.7 ± 13.0 mg/g) was greater (p<0.001) than in leaves (373.0 ± 14.8 mg/g). These data help explain a long-standing question in giant panda foraging ecology: why consume the plant part with the lowest protein and fat during the energetically intensive spring breeding season? Giant pandas likely prefer spring culm that contains abundant mono- and polysaccharides made more bioavailable as a result of reduced fiber content. These data suggest that phenological changes in bamboo plant part nutrition drive foraging decisions by giant pandas.

Captive African (Loxodonta africana) and Asian (Elephas maximus) elephants can experience foot pathologies and arthritis. As a preventative measure against these pathologies and to alleviate the potential discomfort due to concrete substrates, some zoological institutions have renovated elephant housing to increase the amount of natural or shock-absorbent substrates. The objective of this study was to compare behavioral (diurnal and nocturnal) and glucorticoid (e.g., serum cortisol) responses of three female African elephants before, during, and after renovation to their indoor housing floor to assess whether renovations had short-term effects on the elephants’ behavior and stress physiology. Behavioral data were collected using scan-sampling methods, and activity budgets were constructed for each of the three elephants. In addition, the duration of all lying rest activities were recorded. Weekly serum cortisol concentrations were determined with enzyme immunoassay (EIA). Overall, eating was the most prevalent behavior exhibited outdoors during the day, while resting (either in a lying or standing position) were most common during the indoor, nocturnal periods. Although variation existed among the three elephants, all three females spent significantly more time walking and less time eating during the day after the completion of the renovations. The extent to which the three elephants exhibited nocturnal lying rest behavior varied among the elephants, with the oldest elephant exhibiting the least amount (an average of 13.2 ± 2.8% of the nightly behavioral scans) compared to the two younger elephants (an average of 34.5 ± 2.1% and 56.6 ± 2.8% of the nightly behavioral scans). There was a significant increase in lying rest behavior for one elephant and standing rest for a second elephant following renovations. Baseline cortisol concentrations prior to renovations were 3.0 ± 0.4 ng/ml, 4.5 ± 0.5 ng/ml, and 4.9 ± 0.5 ng/ml for the three elephants. Cortisol concentrations remained baseline for two of the elephants throughout and after the renovation period, while one elephant that was pregnant had elevated cortisol during construction. Cortisol concentrations for the pregnant elephant remained higher than baseline once she was introduced to the new flooring and allowed back into the building, but these values were closer to the cortisol concentrations before renovations than during construction. Our findings demonstrate that individual elephants can vary in their behavioral and physiological responses to exhibit modifications. Given that the elephants walked more during the day, two of the three elephants had an increase in rest behavior during the night, and there were minimal changes in cortisol response after the flooring renovations, we conclude that the flooring renovations overall had a positive impact on animal welfare.

During the annual period of bamboo shoot growth in spring, free-ranging giant pandas feed almost exclusively on the shoots while ignoring the leaves and full- height culm. Little is known about the nutritional changes that occur during bamboo shoot growth, if nutritional changes differ among species, or how these changes might influence forage selection. Our objective was to examine the nutrient and mineral composition during three phases of shoot growth (<60, 90-150 and >180 cm) for seven species of bamboo (Phyllostachys (P.) aurea, P. aureosulcata, P. bissetii, P. glauca, P. nuda, P. rubromarginata, Pseudosasa japonica) fed to captive giant pandas at the Memphis Zoo. Total dietary fiber content of bamboo shoots increased (p < 0.0001) from an overall species average of 61% dry matter (DM) at < 60 cm to 75% DM at shoot heights > 180 cm, while crude protein, fat and ash exhibited significant declines (p < 0.05). Phyllostachys nuda had the overall greatest (p = 0.007) crude protein (21% DM) and fat (4% DM) content, and lowest overall total fibre (61% DM) content compared to the other species examined. In contrast, Pseudosasa japonica had the overall lowest crude protein and fat, and relatively higher fibre content (9%, 3% and 74% respectively). Concentrations of Zn and Fe were highest in shoots <60 cm (10-50 μg/g DM) and decreased (p < 0.05) during growth in all species examined. Concentrations of Ca, Cu, Mn, Na and K varied among species and were largely unaffected by growth stage. Due to their higher concentrations of nutrients and lower fibre content in comparison to culm and leaf, bamboo shoots should be a major component of captive giant panda diets when available.