Biology Program

                                                               Penn State Erie, The Behrend College



Dr. Margaret A. Voss

Assistant Professor of Biology

Ph.D., Biology, Syracuse University, Syracuse NY, 2001

M.S., Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse NY, 1995
B.S., Environmental and Forest Biology, SUNY-College of Environmental Science and Forestry, Syracuse NY, 1992


Teaching Interests:

Upper level courses in Behavioral Ecology, Physiological Ecology, Evolution, and Comparative Anatomy.  I approach all of my classes with the belief that students must be given ample opportunity to practice science if they are to become scientists.  I attempt to incorporate student-formulated hypothesis testing into labs wherever possible and to use student generated questions as the basis for class discussions.  I believe that every student brings a wealth of information into my classroom, and I attempt to tap into that resource through interactive Socratic-style discussions when ever possible.

Research Interests:  Behavioral Ecology and Physiological Ecology

Optimal foraging behavior, avian energetics and embryonic development – quantitative predictions and tests of optimal foraging models for intermittently incubating passerines.  I am primarily interested in the trade of between parental self-maintenance during incubation and maintenance of adequate egg temperature for proper embryonic development.

The influence of embryonic development on parental behavior. Intermittent incubators must balance their energy demands with the thermal requirements of the eggs. Mean Egg temperature depends on three components of the session-recess cycle: egg cooling during recesses, and egg heating and equilibrium temperatures during sessions. We tested hypotheses concerning the influence of day length and ambient temperature on the trade-offs between mean egg temperature and foraging time within the context of latitudinal variation in parental investment.  Dr. Caren Cooper (Cornell Lab of Ornithology) and I have been using biophysical models to predict that heat flux from eggs as embryonic development proceeds.  We predicted that heat flux should increase as embryos develop, constraining the length of parental recesses from the nest during intermittent incubation. We have tested for temporal shifts in incubation strategy among Black-capped Chickadees and examined the consequences of different strategies to variation in egg temperature and nestling quality. As predicted, the rate of clutch heat loss increased as embryos aged. Daily incubation strategy shifted 5 days after the onset of night incubation.  Egg temperatures increased as embryos aged corresponding to changes in female behavior. Post-shift, females maintained higher egg temperatures and higher nest attendance through frequent, short recesses, relative to fewer, long recesses prior to the shift. The shift likely minimized egg cooling, thereby lowering the energetic costs of re-warming eggs. The dynamic aspects of parent-embryo trade-offs highlight the need to view incubation along a continuum of thermal contributions of parental care rather than as an all-or-none process.

Male incubation in the Barn Swallow (Hirundo rustica). It has been hypothesized that male birds in North American populations of the Barn Swallow (Hirundo rustica erythrogaster) reduce the negative effects of egg cooling during female absence from the nest by actively incubating.  Most reports of incubation by male H. rustica have not measured egg temperature in a manner appropriate to test this hypothesis.  Male presence at the nest may also serve to reduce egg predation or nest parasitism, so it is important to determine whether developing embryos receive any substantial thermal benefit from this behavior.  This work examines the effect male presence might have embryonic development through egg temperature records, field observations, and calculations of Q10, the rate at which embryonic development could be increased through increases in egg incubation temperature.

The effects of traffic noise on mate display, reproductive fitness, immune function, foraging, and incubation behavior. The increased traffic noise associated with some forms of habitat fragmentation may modify normal reproductive behaviors and alter life history strategies by changing the environmental backdrop for breeding displays.  For example, a noisy environment might make the reproductive strategy of sneaking onto other males’ territories to gain access to females more successful. This “sneaker” male strategy might proliferate in a population in which it was rarely seen before, altering the breeding system and reducing fitness for high quality males that continue to choose the more traditional strategy of defending territories. My students and I have monitored nesting birds on Behrend’s campus for the past four years to test some aspects of this idea. All of our sites are comparable in prey density and nesting opportunities (i.e., number of nest boxes and natural tree snags), but vary in sound level. Some bird species are quite plastic in their ability to shift song frequency and pitch to be heard above the background noise. Black-capped chickadees, one of the species we have been working with, are physiologically limited in this regard. We predict male chickadees defending noisy territories will be highly susceptible to extra-pair paternity due to their inability to compensate for background noise, regardless of their social rank. We have collected data from nesting pairs of chickadees on ambient sound levels, incubation patterns, egg temperatures, social rank, and blood samples for paternity analysis and immune function tests.  Preliminary results suggest an increase in extra-pair paternity on noisy sites due to impaired female perception of male quality.

Does variation in microclimate actually benefit developing avian embryos? When animals are kept in captivity, they are often maintained at what we believe to be optimal environmental conditions. If we think of pathogens and their host organisms as being in a continual evolutionary struggle, an arms race of sorts, we could postulate that constant environments should favor the pathogens. Bacterial generation times are much shorter than those of host species, allowing for rapid multiplication under constant environmental conditions. Thus, what we perceive as variable and therefore “non-optimal” environmental conditions might actually be beneficial to some host organisms. I believe this might explain the phenomenon of intermittent incubation, which is clearly less efficient than constant incubation from the point of view of the developing embryo. I have recently begun an interesting collaboration with two colleagues at Behrend that would make use of the climate controlled nest boxes to test this idea. We believe that nest microclimate is maintained through structural and behavioral means to augment embryonic development. The choice of plant material used in construction, the content and structure of the nest lining (feathers, fur, grasses), and parental incubation behavior may also interact to regulate the microbial flora of nests. The maintenance of beneficial microbes while simultaneously minimizing pathogenic strains may be an important factor in decreasing embryonic mortality. We recently proposed a study to NSF that seeks to 1) characterize the microbial communities present in nests and eggs of several species of North American birds, 2) investigate correlations between species specific nest structure and microbial flora, 3) determine if microbial communities change in composition before and after nestling fledge, 4) determine if microbial communities change in composition when nest microclimate is altered, and 5) document changes in parental incubation behavior and embryonic mortality associated with composition changes in microbial communities in nests. 

Recent Publications:

Ellis-Felege, S. and M.A. Voss.  (In review). Changes in Embryonic Development as a Cue for Parental Time Allocation during Avian Incubation.  The Wilson Journal of Ornithology.


Cooper, C. B. and M. A. Voss.  (In review).  Incubation Patterns Reflect Dynamic Temporal Changes in Developing Clutches.  The Auk


Ardia, D.R. , J.H. Pérez , E.K. Chad, M.A. Voss , and E.D. Clotfelter. 2008. Temperature and Life History: Experimental Heating Leads Female Tree Swallows to Modulate Egg Temperature and Incubation Behavior.  Functional Animal Ecology  (Accepted ).


Voss, M.A. , M.A. Rutter, N. Zimmerman , and K. Moll.  2008. The Adaptive Value of Thermally Inefficient Male Incubation in the American Barn Swallow (Hirundo rustica erythrogaster).  The Auk 125 (3):637-642.


Voss, M.A., Hainsworth, F.R., Ellis-Felege, S.N.  2006. Use of a New Model to Quantify Compromises between Embryo Development and Parental Self-maintenance in Three Species of Intermittently Incubating Passerines. Journal of Thermal Biology, pp 453-460.


Hunnicutt, DW, Cingolani, J, and M.A. Voss. 2005. Use of mtDNA to Identify Genetic Introgression among Related Species of Catfish. In press, Journal of Great Lakes Research 31(4) 482-491.


Hainsworth, FR, and M.A. Voss. 2002. Intermittent Incubation: Predictions and Tests for Time and Heat Allocations. Chapter 15 in Avian Incubation: Behaviour, Environment and