Graduate student Kim Brand (Univ. South Florida) demonstrates her electronic balance used to weigh Florida scrub-jays; photo by Nancy Deyrup.

Research intern Rachel Butzler (Penn State Univ.) collects algae samples from a seasonal wetland at Buck Island Ranch; photo by Patrick Bohlen.

Plant Ecology. The negative chemical effects of Florida rosemary (Ceratiola ericoides) on seven subordinate rosemary scrub species was studied by intern Molly Hunter (see photo, page 37 top). Leachates with rosemary leaves or litter suppressed germination of species that tend to be found in gaps among rosemary shrubs. This allelopathy may therefore restrict the distribution of endangered scrub species to recently burned areas and natural gaps. Molly is now a graduate student at the University of Illinois at Chicago.

Christine Hawkes (Univ. Pennsylvania) completed her Ph.D. thesis in 2000, on the interaction of biological soil crusts with vascular plants in Florida scrub. These crusts, which consist of algae, cyanobacteria, and other components, aggregate surface soil in areas with low vegetation cover such as deserts and shrublands. Christine found that crusts were most abundant 10-15 years postfire and in gaps between dominant shrubs. Crusts affected germination of three rosemary scrub plants, but the effects were variable among years. Mycorrhizal plants were able to obtain nitrogen from soil crusts, whereas non-mycorrhizal plants depended on soil or precipitation for nitrogen. Soil crusts also fix nitrogen, so they may alternatively supply or compete with plants for this nutrient. Christine is now a postdoc at the University of California at Berkeley.

For his intern project, Will Satterthwaite (now a graduate student at Univ. California-Santa Barbara), assisted by Pedro Quintana-Ascencio, assessed population viability using long-term data collected by Eric Menges and the plant lab on scrub buckwheat (Eriogonum longifolium var. gnaphalifolium). Scrub buckwheat populations declined in years without fires (mean finite rate of increase = 0.978) but increased during years in which they were burned (mean finite rate of increase = 1.246). Frequent and more complete burns promoted population viability. Extinction probabilities stayed near zero for complete fires occurring every 3 years, but exceeding 50% for complete burns less frequent than once per 15 years. Frequent (1-3 year) patchy burns or moderately frequent (3-15 year) complete burns should promote viable populations.

Ornithology. Student research in the Bird Lab continues to focus on graduate students and their thesis and dissertation work. Tina Fleischer obtained a M.S. degree from the University of South Florida (USF) during fall 2000. Her thesis title was "Reactions of Florida scrub-jays (Aphelocoma coerulescens) to eggs and shams added to their nests." Avian brood parasites, such as certain species of cowbirds, are now invading the range of the Florida scrub-jay. Tina tested the reaction of nesting scrub-jays to experimentally introduced foreign eggs and sham eggs. All shams, most cowbird eggs, and all other non-scrub-jay eggs were ejected within one day of insertion. Most foreign scrub-jay eggs were accepted. Cowbirds appear to pose little threat to scrub-jays. Reed Bowman also served on Tina’s committee.

William Keating obtained an M.S. degree from USF during spring 1999. His thesis title was "Nocturnal roosting behavior of the Florida scrub-jay." The jays initiated and terminated diurnal activity earliest relative to dawn during late summer and early fall. The jays initiated diurnal activity later and terminated diurnal activity earlier during winter. Scrub-jays roosted in dense clumps of low growing scrub oaks, palmettos, or lyonias. Roost-site fidelity presumably reduces the time required to coordinate activities at dawn. Reed Bowman also served on Bill’s committee.

Kimberly Brand (see photo this page) finished field work on her Master’s thesis (USF) and is writing the results. Her research pertains to annual mass changes of breeding Florida scrub-jays. Basic to the field work is the weighing system we have developed. Jays are trained to jump onto an electronic pan balance (connected to a computer) to obtain peanut bits; the computer records their weights. Reed Bowman is a member of Kim’s committee.

Avian Ecology. Student research in the Avian Ecology Lab is focused on suburban Florida scrub-jays and always with comparisons to jays in natural habitats at Archbold Biological Station.

Artie Fleischer completed his M.S. thesis (University of South Florida (USF)) on the effects of supplemental food on the behavior of pre-breeding females. He found that supplemented birds decreased foraging time and increased perching time and that food handling rates were most strongly related to time of breeding. Matthew Shawkey, MS student at USF, continued his research on the proximate mechanisms of brood reduction in suburban scrub-jays. Matt’s research suggests that both the quantity and quality of food delivered to nestlings may be poorer than in natural habitats. However, the effects of limiting food resources may be exacerbated by longer hatching spans and larger nestling size asymmetries at hatch completion. Both patterns increase the amount of brood reduction, which is an important factor limiting reproduction in this population. Sonja LeClair tested the hypothesis that scrub-jay brood reduction is mediated, in part, by food limitation, by providing nestlings with supplemental protein twice a day between hatching and day 5. She found that the smallest nestlings in the brood had higher survival rates than control nestlings and fledging success and post-fledging survival was higher in supplemented broods. Ari Levine examined possible food limitation in the fall by examining variation in acorn abundance and caching behavior of suburban scrub-jays. Suburban jays cached many fewer acorns than jays at Archbold and instead, diverted that foraging time to feeding on arthropods. Because supplemental food is available throughout the year, jays may not depend on acorns during periods of low arthropod availability.

The impacts of urbanization begin long before houses are built. Roads dramatically alter the fire regime. Brent Sewall studied the relative impacts of fire suppression and urbanization on avian community structure in the scrub-jay suburbs. He found that bird-species diversity and richness increased with urbanization, but evenness declined.

Entomology. Joshua Ladau (Cornell Univ.) studied the predatory habits of the grizzled mantis, Gonatista grisea, documenting its strong tendency to face downward on tree trunks while waiting for prey to come within striking distance. He showed that the mantis can catch insects when facing upward as easily as in the normal down-facing position, and is now working on the hypothesis that more insects climb up tree trunks than climb down. Teresa Justice (Eastern Carolina Univ.) began a study of the genetics of Florida scrub insects on various ridges in Florida. Her goal is to explore and quantify the divergence of populations. Included in this study so far are scrub grasshoppers, scarab beetles, sand roaches, and pygmy mole crickets.

Mac-Arthur Agro-ecology Research Center. Matt Baber (Florida International Univ.) completed his Ph.D. dissertation in spring 2001, on the importance of landscape heterogeneity and local biotic and abiotic factors in structuring tadpole community structure in seasonal wetlands. Matt’s research showed that the structure of frog communities in isolated wetlands was strongly influenced by the landscape surrounding the wetland (see MAERC article, Wetlands Research section, for details). Matt is currently a postdoc at University of New Hampshire.

Lakeisha Hill (Unv. Florida), a Master’s student in the Soil and Water Sciences Department, is doing her Master’s research on storage and forms of phosphorus (P) in different soil layers across topographic gradients in our experimental pastures. Previous work showed that surface soils in the improved pastures have more available P than in semi-native pastures. Lakeisha’s research will determine whether there is significant storage of P in deeper soil layers.

Several interns have done projects on nutrient dynamics or productivity in seasonal wetlands at MAERC. Laura Spangler compared organic matter storage, P concentrations, and inorganic nitrogen (N) in wetlands sediments from improved and semi-native pastures and the Audubon Kissimmee Prairie Preserve. Rachel Butzler (see photo, this page) examined algal productivity in seasonal wetlands in improved and semi-native pastures. Wilhelmina Tsang examined organic matter in wetland sediments in relation to pasture land use and found that land-use affected both the quality and quantity of organic matter in wetland sediments.

Two MAERC interns studied plant communities and productivity. Tim Dickson set out to examine the interactive influences of water, nutrients and grazing on productivity in semi-native tallgrass prairie at MAERC. Christy Edwards examined the distribution of bromeliads in relation to microhabitat characteristics in hammocks at MAERC. Tim is currently a doctoral candidate at the University of Kansas and Christy is entering a Ph.D. program in Botany at the University of Florida.