Teaching Interests
BSC 692 Introduction to Ecological
Modelling
Research Interests
Much of my research explores ecological
and behavioral processes that operate across different
spatial scales in avian migratory systems. Since the
health of many migratory bird populations remains in
question after years of pervasive land use change,
understanding migration biology is important to their
conservation. However, most nearctic/neotrpical
migratory birds fly at night, stopping only briefly
between flights to rest and refuel before continuing
migration. For this reason, they make challenging study
subjects and much avian migratory ecology and behavior
remains unknown or poorly understood, especially at the
larger spatial scales over which migration occurs.
Doppler weather surveillance radar has proven useful for
studying nocturnal avian behavior at large scales, and
development and application of radar as a biological
tool remains a focus of my research. Below is a small
sample of the rich variety of migratory behavior
captured by radar (pages take long time to download with
low bandwidth connections).
My current collaborative
research falls into four areas
- Ecological and behavioral modeling
We are building spatially explicit,
individual-based models exploring how the
distributions and behaviors of individual migrants
collectively lead to emergent migratory patterns
observed across large spatial scales. This
compute-intensive model will iteratively converge
toward ecological and behavioral parameters that
yield virtual distributions of birds aloft that best
match those recorded by weather radar. Converged
model parameters describe what bird distributions in
the landscape and behaviorl traits during migratory
exodus led to patterns observed on radar.
- Avian mortality
Birds encounter many natural and
anthropogenic hazards during migratory passage. In
part for this reason, many assert that migration is
risky behavior, yet this position is supported by
little research. Sources of mortality remain largely
speculative, because the specific conditions or
circumstances leading to bird deaths seldom occur
where they can be monitored or observed. I am
collaborating on researching both the theoretical
basis for risk associated with migration and
assessing risk to migrants posed by different
potential sources of mortality. In a recent case
study, we examined the causes of mass bird mortality
associated with Lake Michigan as a supposed barrier
to migration. I am also collaborating on research
led by J. Gehring to understand the risk
communication towers pose to birds during flight.
- Habtitat use
Many factors influence avian
distributions during migratory stopover, and perhaps
most important among these are anthropogenic changes
to the landscape. In collaboration with scientists
from the USGS National Wetlands Research Center,
data from surveillance radar will inform structural
equation models developed by J. Grace that predict
the influence of human development and other habitat
characteristics on habitat use by migratory birds.
Other research in Michigan and in landscapes along
the Gulf of Mexico applies this capability of radar
in associating birds with their stopover habitats to
identify landscape vegetative characteristics
important to birds during migratory stopover.
Efforts are also underway to apply the same
techniques to identify important waterfowl habitats.
- Software and Instrumentation
In recent years, interest in applying
radar to biological questions grew considerably as
research reported on the unexplored potential of
weather radar as a biological tool. Yet the most
resolute data from weather radar systems is
inaccessible to most biologists interested in
application. We are developing software to bridge
this technical gap. Software will provide biologists
with radar analytical tools and the ability to
convert obscure data formats into more generally
useable forms. Weather radar is a broad brush
instrument which capably illustrates large scale
structure in animal distributions aloft, but it does
so at the expense of details on the behavior of
individuals. Therefore, we are developing an
inexpensive portable radar for small scale research
applications that complements weather radar by
focusing on the
behavior of individual targets.
Representative Publications
Cryan, P. and R. Diehl. In press.
Analyzing bat migration. Invited chapter. 2nd ed.
Behavioral and ecological methods for the study of bats.
Diehl, R. H., R. P. Larkin. 2005. Introduction to the
WSR-88D (NEXRAD) for ornithological research. In:
Ralph CJ, Rich TD, editors. Bird Conservation
Implementation and Integration in the Americas:
Proceedings of the Third International Partners in
Flight Conference 2002 March 20-24. Asilomar,
California: Pacific Southwest Research Station, Forest
Service, U.S.D.A., Gen. Tech. Rep. PSW-191, Albany, CA.
p 876-888.
Larkin, R. P. and R. H. Diehl. In press.
Spectrum width of birds and insects on pulsed Doppler
radar. IEEE Transactions on Geoscience and Remote
Sensing.
Diehl, R. H., R. P. Larkin, and J. E.
Black. 2003. Radar observations of bird migration over
the Great Lakes. Auk. 120:278-290.
Wikelski, M., E. Tarlow, A. Raim, R.
H. Diehl, H. Visser, and R. P. Larkin. 2003. Costs of
migration in free-flying songbirds. Nature. 423:704.
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