Enticing nonhuman primates to forage for their standard biscuit ration

Ordinary feeder-boxes for macaques were converted into food puzzles by remounting them onto the square mesh (22 × 22 mm) of the front of the cages, away from original access holes. Feeding a standard ration of bar-shaped biscuits (40 × 24 × 16 mm; Purina Monkey Chow #5038; 236 g per animal), 8 adult pair-housed male rhesus macaques spent, on average, 61.0±15.6% of the first 30 min retrieving biscuits from food puzzles, but only 0.5±0.1% from feeder-boxes. Their total amount of time engaged in gathering food was, on average, 141 times higher at food puzzles (42.2±7.2 min) than at feeder-boxes (0.3±0.1 min). It was concluded that using feeder-boxes as food puzzles, baited with the standard biscuit ration, offers a cost- and work-effective way to promote foraging activities in captive nonhuman primates. © 1993 Wiley-Liss, Inc.     

Evaluating timing in spontaneously hypertensive and Wistar-Kyoto rats using the peak procedure

A core deficit in timing may underlie the symptoms of attention-deficit/hyperactivity disorder (ADHD). Timing deficits have been observed in ADHD-diagnosed children but have yet to be fully explored in the spontaneously hypertensive rat (SHR), a purported model of ADHD. We asked whether SHRs demonstrate ADHD-like timing deficits using the peak procedure. Response rates across peak intervals were modeled using the sum of two Gaussian curves. Results showed that SHRs peaked earlier than Wistar-Kyotos based on 4 s intervals that contained the individuals’ maximum response rates but not based on model parameters. The strains showed approximately equal precision of timing based on Weber fractions derived from model parameters, a result that replicates previous findings and does not support the use of SHRs to model this aspect of ADHD.     

Guardians' Knowledge and Husbandry Practices of Feline Environmental Enrichment

Feline environmental enrichment can prevent numerous disorders including anxiety, stress, obesity, and feline idiopathic cystitis. Despite its easy implementation and low cost, it has received little attention. The main goal of this study was to assess guardians' knowledge concerning feline environmental enrichment and husbandry practices. A questionnaire was given to 130 companion animal guardians at the Lisbon Veterinary Faculty's Teaching Hospital. The applications of 22 environmental enrichment measures related to food/water, litter box, and space/entertainment areas were evaluated. The majority of the households studied (74.6%) had a moderately enriched environment. Hygiene-related measures were those most adopted by guardians, while those requiring guardians' commitment or previous awareness were the least implemented. A rating scale was proposed and applied to assess feline domestic environmental quality.     

Primate puzzleboard: A simple environmental enrichment device for captive chimpanzees

An environmental enrichment device was designed and evaluated for captive chimpanzees. The puzzleboard consisted of a 61-cm, square piece of clear plastic with holes of various sizes drilled into the center. The puzzleboard was bolted to the roof of a chimpanzee enclosure. Flavored primate treats were arranged on top of the board, and the chimpanzee used a finger to manipulate the food across the board to be retrieved through the larger holes. The behavior and puzzle use of 29 chimpanzees housed in eight groups were evaluated while the device was empty and while filled with food. For each group, four 1-hr scan samples were recorded for each condition. Data showed that an average of 40 min elapsed from the time the puzzleboard was filled to the last recorded contact by a subject. Mean individual use ranged from 4.8 to 23.8 min/hr. Female chimpanzees used the puzzle significantly more often than did males. Aggressive, affiliative, inactive, and self-directed behaviors were significantly reduced when the puzzle was filled. In addition, the puzzleboard was inexpensive, sturdy, and easily constructed, mounted, and operated.     

Potential effects of elevated atmospheric carbon dioxide on benthic autotrophs and consumers in stream ecosystems: a test using experimental stream mesocosms

Elevated atmospheric carbon dioxide (eCO₂) has been shown to have a variety of ecosystem‐level effects in terrestrial systems, but few studies have examined how eCO₂ might affect aquatic habitats. This limits broad generalizations about the effects of a changing climate across biomes. To broaden this generalization, we used free air CO₂ enrichment to compare effects of eCO₂ (i.e., double ambient ～720 ppm) relative to ambient CO₂ (aCO₂～360 ppm) on several ecosystem properties and functions in large, outdoor, experimental mesocosms that mimicked shallow sand‐bottom prairie streams. In general, we showed that eCO₂ had strong bottom‐up effects on stream autotrophs, which moved through the food web and indirectly affected consumer trophic levels. These general effects were likely mediated by differential CO₂ limitation between the eCO₂ and aCO₂ treatments. For example, we found that eCO₂ decreased water‐column pH and increased dissolved CO₂ in the mesocosms, reducing CO₂‐limitation at times of intense primary production (PP). At these times, PP of benthic algae was about two times greater in the eCO₂ treatment than aCO₂ treatment. Elevated PP enhanced the rate of carbon assimilation relative to nutrient uptake, which reduced algae quality in the eCO₂ treatment. We predicted that reduced algae quality would negatively affect benthic invertebrates. However, density, biomass and average individual size of benthic invertebrates increased in the eCO₂ treatment relative to aCO₂ treatment. This suggested that total PP was a more important regulator of secondary production than food quality in our experiment. This study broadens generalizations about ecosystem‐level effects of a changing climate by providing some of the first evidence that the global increase in atmospheric CO₂ might affect autotrophs and consumers in small stream ecosystems throughout the southern Great Plains and Gulf Coastal slope of North America.     

Carbon dioxide enrichment reduces shoot growth in sweet chestnut seedlings (Castanea sativa Mill.)*

Abstract. Two-year-old potted sweet chestnut seedlings were grown at 350 ppm CO₂ and 700 ppm, day and night in constantly ventilated tunnels during two full growing seasons, near Paris, France (48° N, 2° E). Enrichment with CO₂ caused an unusual shoot growth response. After the end of July, stem elongation ceased in 62% of the CO₂ enriched plants as compared with 37% in the control. The leaves of CO₂-enriched seedlings showed early senescence, indicated by premature yellowing and a decrease in chlorophyll content. This was associated with nutrient dilution brought about by the rapid growth of these trees. The increase in total dry weight of the CO₂-enriched seedlings was essentially the result of increase in the root dry weight (69%). Shoot weight decreased by 22% relative to the control. Total leaf area per enriched plant was 25% smaller than the control. This unusual pattern of growth and carbon allocation of the CO₂ treated Chestnut trees emphasizes the concept of a response specificity within trees to an increase of atmospheric CO₂.