Search

The optimal prey selection hypothesis, a part of Optimal Foraging Theory, uses prey energy content and forager searching and handling times to predict when a forager will choose only the most profitable prey and when it will include less profitable prey in its diet. I tested the hypothesis using eastern gray squirrels as foragers and pairs of prey--sunflower fruits and seeds, and pumpkin seeds and embryos-- that differed in handling time. In all foraging trials, the squirrels consumed both prey types, but showed a partial preference for the less profitable prey (sunflower fruit and pumpkin seed). For squirrels foraging on pumpkin seeds and embryos, the hypothesis, which predicts that the more profitable prey (embryos) alone would be selected, was not supported by a partial preference value significantly greater than 0.5 which would indicate that both prey types were consumed. The hypothesis may be limited to laboratory conditions in which prey are presented sequentially, a condition not met in the experiments described here where prey types were offered together and were constantly mixed as the squirrels searched for prey in a sand-containing dish. Instead, squirrels showed a slight preference for larger prey which may result from higher encounter rates or may result from squirrels using a "rule of thumb:" when hungry, consume prey as they are encountered. [ABSTRACT FROM AUTHOR]

The author discusses the history of the South Dakota Academy of Science, fluctuations in the memberships of the periodical from year to year and milestones achieved by the Academy including first symposium on mercury pollution, development of website and acceptance of student members.

The article offers information about a meeting of the South Dakota Academy of Science, organized by Dakota State University, in Oacoma, South Dakota, from April 8-9, 2011. It mentions that the composition of the Executive Council was also discussed during the meeting. It further mentions that the undergraduate winners of the poster presentation including Shania Sabel, Paul Mallory and Marissa Kern were honored.

The northern half of Warren Woods State Park, a 309-acre old growth, American beech-sugar maple forest in Berrien County, Michigan, has been the focus of numerous studies since 1919. The southern half was clearcut in the late 1800s and then pastured until 1919, at which time it contained a mix of perennial grasses, herbs and shrubs. In 2018, I counted and measured the diameter at breast height (dbh) of all trees > 2.54 cm dbh in 281 -- 100 m2 circular plots randomly located along E-W transects that were 30 m apart. My objectives were to 1) determine the progress of secondary succession by describing the current structure and composition of the second growth forest that had developed over 100 years; 2) to compare this to the old growth, beech-maple forest to the north which was its most probable seed source; and 3) to use size class distributions to predict the future community composition. Based on importance values, the second growth forest is dominated by red maple and American beech and contained an additional 16 tree species of lower importance. Compared to the current composition of the old growth forest, the second growth forest had on average smaller diameter trees with a lower diversity and with dominance share more widely. Based on size class distributions of the dominant species, the second growth forest appears to be developing into a beech-maple forest similar to the forest immediately to its north. [ABSTRACT FROM AUTHOR]

An abstract of the article "Fox Squirrels Do Not Prefer Salted Over Unsalted Sunflower Fruits," by Robert Tatina is presented.

Previous studies have shown that animals foraging in artificial patches quit feeding at higher giving up densities (GUDs) of food in risky locations compared to safe locations. Risky locations are those at which threats of predation are high. The purpose of my study was to determine if foragers, specifically urban fox squirrels (Sciurus niger), change their food preference under risk of predation. For 40 days in winter 2007-2008 in Mitchell, South Dakota, I exposed random combinations of sunflower fruits and seeds to squirrel foraging in four trays. Two trays were placed in a yard (risky location) into which a dog was periodically released. Two others were placed outside the yard (safe location), a location to which the dog had no access. At the end of each day I weighed seeds and fruits separately; these weights were the GUDs. The GUDs for each food type from risky and safe locations were compared using a Student's t-test. I also determined partial preference for fruits for each day in each tray and compared these using a Student's t-test. Mean GUDs for sunflower fruits from the risky location were 4.48 ± 0.91 (se) and 4.44 ± 0.91 (se). These were significantly greater than mean GUDs (1.58 ± 0.40 (se) and 1.67 ± 0.49 (se)) from the safe location (t = 4.85, df = 121, p = 0.0001). Likewise, mean GUDs for sunflower seeds from the risky location (10.11 ± 1.86 (se) and 10.09 ± 1.82 (se)) were greater than mean GUDs (4.56 ± 0.83 (se) and 5.56 ± 1.48 (se)) (t = 4.25, df = 136, p = 0.0001) from the safe location. Mean partial preference for fruits (PPF) in the risky location was 0.553 ± 0.018 (se) which was significantly greater than 0.500 (z = 7.67, N = 53, p = 0.00001). Mean PPF in the safe location was 0.590 ± 0.009 (se), also significantly greater than 0.0500 (z = 14.02, N = 61, p = 0.00001). PPFs were not different between the risky and the safe locations (t = 1.87, df = 79, p = 0.066). When urban fox squirrels foraged in the risky location their GUDs were higher than for the safe location because they balanced foraging against predator vigilance. However, they did not change their food preference. Natural selection has conserved that foraging behavior which is optimal (i.e., yields a net energy gain) regardless of the riskiness of the foraging location. [ABSTRACT FROM AUTHOR]