Dept. Ecology &Evolutionary Biology, Princeton
Alexander von Humboldt - Fellow
Interests: My main interests focus on behavioral and physiological
stress responses of free-ranging animals solicited by the approach
of a human or a predator. On the proximate level I am interested
in modifications of the stress response due to differences in individual
characteristics, e.g. social status, body condition, prior experience
and learning. On the ultimate level I am interested in the fitness
consequences of individual differences in stress responses. The
methods applied are derived from behavioral ecology and endocrinology.
In collaborative projects the scope of these investigations is extended
with the study of the interactions of an animal's stress response
and the functioning of its immune system.
here for list of publications
M.S., University of Munich, Germany (Zoology, Botany, Wildlife Biology)
Ph.D., University of Munich (Zoology, Behavioral Ecology)
Postdoc., Ben Gurion University, Israel
Research Associate, Max-Planck Research Unit for Ornithology
and consequences of low wariness in
is famous for the tameness of its wildlife what
is generally attributed to the lack of large terrestrial predators.
Choosing the marine iguana (Amblyrhyhnchus cristatus) we want
to understand the relationship between the perception of a
potential threat, the activation of a HPA stress response,
and the initiation of, or, the lack of flight behavior. When
animals demonstrate low wariness, is human approach not perceived
as a potential threat, i.e. a physiological stress response
is not mounted? Or, alternatively, is an increase in stress
hormones not translated into a flight response? A comparative
approach serves to reveal differences between populations
with different impact by tourism and/or introduced predators.
An experimental approach will reveal the underlying mechanisms
that are responsible for such differences. This project shall
also contribute to applied conservation biology by offering
a better understanding of the impact that tourism and
introduced predators might have on the fitness of
Galápagos marine iguanas.
response and fitness in Marine Iguanas
of the HPA-axis during potentially
stressful situations has evolved to bring the animal into
a physiological state of emergency that is helping to cope
with the situation and to increase survival. The
Marine iguana is a good model to investigate the
relationship between the stress response and potential fitness
benefits, because individuals vary largely in body size, body
condition, and social status. We are trying to characterize
fitness differences between individuals that can be related
to differences in the functionality of their HPA-axis.
collaboration with Prof. Michael Romero, Tufts
University, and Silke Berger, University Ulm, Germany
hormones and the immune system in Marine Iguanas
Baseline and stress-induced
elevations of the "stress-hormone" corticosterone
are expected to influence the animals' responsiveness to experimental
immune challenges. We are testing these relationships in free-ranging
marine iguanas applying PHA and KLH challenges and using blood
cell counts to demonstrate immune cell trafficking and to
determine hematological indices. We are especially interested
in factors explaining individual differences in the immune
response due to social status, body condition, sex, and age.
collaboration with Silke Berger, University Ulm, Germany;
Lynn B. Martin, Princeton University; Prof. Mark Mitchell,
Louisiana State University
collaboration with Prof. D. Ward, Stellenbosch University,
Matieland, S-Africa; Adam Green,
University of Wisconsin, Madison; Prof. A. Golan-Goldhirsch,
Dr. O. Barazani & Dr. S. Volis all Ben Gurion University,
mistletoes, and human settlements
This is a multidisciplinary
study on a system composed of a desert mistletoe (Plicosephalus
acaciae), its main bird vector, the Yellow-vented bulbul (Pycnonotus
xanthopygos) and human settlement activity in the Arava valley
between Israel & Jordan, which favors bulbul populations.
We are characterizing the mechanisms of fruit dispersal in
this system to explain the patterns of distribution of the
plant through the birds' behavior as a function of human settlement
activities. Past work consisted of behavioral studies on bird
activity ranges, of physiological experiments on the birds
gut passage time as well as the mistletoe establishment capacity,
of analysis of movement data for the determination of a seed
shadow, and of spatially explicit geographical data on the
species' distribution. We want to add information on the genetic
distances between populations.
differences in testosterone
concentrations in breeding birds
bird species usually face a rigid annual cycle that requires
tight timing of reproductive events. In addition, many birds
in the temperate zones are migratory and face strong competition
for territories and sexual partners during the relatively
short breeding season. Therefore, it is generally assumed
that temperate zone birds demonstrate higher testosterone
concentrations during the reproductive period than tropical
species. We are testing this prediction in captive European
Stonechats (Saxicola torquata ssp.) from different populations
of tropical and temperate origin, held in a common garden
situation, using a recently established non-invasive method
of quantification of fecal steroid metabolite concentrations.
in collaboration with Prof. E. Gwinner & Dr. W. Goymann,
both at the Research Unit for Ornithology, Max-Planck
Society, Andechs, Germany
Gwinner, E., T. Rödl, H. Schwabl, 1994. Pair territoriality
of wintering stonechats: behaviour, function and
hormones. Beh. Ecol. Sociobiol. 34: 321-327.
1994. The wintering of territorial Stonechat pairs Saxicola
torquata in Israel. J. Ornithol. 136: 423-433.
& H. Flinks, 1996. Nutrition of Stonechats (Saxicola torquata)
and Mourning Wheatears (Oenanthe
lugens) wintering sympatrically in Israel. Ecology of Birds
1999. Environmental factors determine numbers of overwintering
European Stonechats Saxicola rubicola
- a long term study. Ardea 87(2): 247-259.
& D. Ward (2002). Host recognition in a desert mistletoe:
early stages of development are influenced by
substrate and host origin. Funct. Ecol. 16(1): 128-134.
& E. Gwinner (subm.) State-dependent territorial aggression
in wintering European Stonechats (Saxicola
torquata). Behav. Ecol. Sociobiol.
M., Rödl, T. Vant Hof, T. & Gwinner, E. (subm.)
The function and control of song in overwintering stonechats.
Rödl, T. 1997. Relationship between status and aggression
in wintering stonechats, Saxicola torquata, in Israel.
in: M. & B. Taborsky (eds.). Advances in Ethology 32,
suppl. to Ethology: p.147. Proc. of the International
Ethological Conference, Vienna.
M., T. Rödl, V. Canoine & T. Vant Hof 1998.
Is singing in wintering Common Stonechats Saxicola torquata
associated with territory density? In: Adams, N.J. & R.H.
Slotow (eds) Proc. 22 Int. Ornithol. Congr., Durban:
BirdLife South Africa.
& Gwinner, E. 2002. "Assessing the likelihood of
cross-seasonal pair associations in a wintering
migrant", Smithonian Symposium "Birds of Two Worlds",
Popularization of my work
Max-Planck-Research 2/2002: 50-53. Christina Beck: Stonechats
in Dummy Test.
Zeitung [major German newspaper] 10. Juli 2002: R5. Bernhard
Granier: Birds have no jetlag.
Germany Oct. 2002: 16. Margit Enders: Platonic love
4/2003: Christina Beck: ... (in press).