Profile
I am ecologist interested in behaviour, conservation, and evolution of migratory
animals. Our lab addresses a variety of topics including effects of climate change and
habitat loss throughout the annual cycle in seabirds and songbirds, the role of
migration networks and seasonal interactions in predicting changes in population
size, the development of optimal conservation plans for a range of migratory
species, the costs and benefits of migration, and life-history trade-offs between
different periods of the annual cycle. My research integrates behavioural and
demographic field research with landscape ecology, theoretical and empirical
modeling, and biogeochemistry. Our lab conducts field research in a number of
locations including the BC Pacific coast, Costa Rica, the Bay of Fundy, and right here
on the University of Guelph campus.
Education
B.E.S. – University of Waterloo (1998)
M.Sc. - York University (2000)
Ph.D. - Queen's University (2004
NSERC/Killam Postdoc, University of British Columbia (2006)
Research
General overview
Migration represents one of the most complex and fascinating behaviours in nature.
Found in a wide variety of taxa including insects, fish, reptiles, mammals, and birds,
migration can span thousands of kilometers and occur over multiple life-history
stages and habitats. Identifying the factors that influence individual success and
population abundance requires knowledge of how events are linked throughout the
migratory cycle. The primary obstacle, thus far, has been the inability to track
individuals over large geographic distances, resulting in research that has been
limited to isolated stages of the migratory cycle. This has made it challenging to
determine how populations are spatially connected between periods and for
understanding how events in one season carry-over to influence success in
subsequent seasons. Novel technologies, such as stable isotopes, trace elements and
radio-telemetry are beginning to bridge these gaps by providing the ability to
integrate life-history and demographic information throughout the migratory cycle.
The long term goals of my research are: (1) understand how events within and
between seasons interact with behaviour and habitat quality to influence population
abundance and life-histories, and (2) parameterize and develop a set of predictive
models that can be used to test aspects of life-history evolution and population
dynamics in migratory animals, (3) develop and refine sets of accurate and noninvasive methods to track individuals over large geographic distances, and finally
(4) apply year-round populations models to construct optimal conservation plans
that can be used for a variety of species worldwide. Below, I briefly outline four
primary areas of research in our lab.
Migratory connectivity
Migratory connectivity is the degree to which populations mix between different
periods of the annual cycle. Uncovering patterns of migratory connectivity is critical
for understanding the evolution and dynamics of migratory populations,
particularly for many species that have experienced severe declines over the past
few decades. Our knowledge of connectivity for most species, however, is extremely
limited because of the difficultly of following individuals over large geographic
distances. Our current and recent work has used stable isotopes, trace elements, and
genetic markers to examine the connectivity of (a) small migratory songbirds (Tree
swallows Tachycineta bicolor, American redstarts Setphaga rutucilla, Cerulean
warblers Dendroica cerulea) between their temperate breeding and tropical
wintering grounds, (b) Western sandpipers (Calidris mauri) between their
wintering grounds in Central and Southern America and breeding grounds in Alaska
and Russia, and (c) Monarch butterflies (Danaus plexippus) between breeding
populations in eastern North America and Mexican wintering grounds. We continue
to refine and develop additional markers and statistical methods that can be used to
track animal movements. Some of our recent work involves examining how heavy
stable isotopes, such as strontium, vary predictably over large geographic ranges
and refining assignment tests that consider multiple markers and multiple sources
of error. At our ‘local’ breeding site at the University of Guelph, we continue to
examine the causes of variation in light isotopes using one of our favourite model
species, the Tree swallow.
Seasonal interactions
Understanding the evolution of life-histories and the factors that limit and regulate
migratory populations requires knowledge of how events interact throughout the
annual cycle. Some of our recent empirical work using stable isotopes has provided
evidence that the quality of habitat and diet during the non-breeding period in
passerines and seabirds can influence reproductive success in the subsequent
breeding season. Using a unique automated telemetry system, we are currently
examining the trade-offs between reproduction, parental care, molt and migratory
behaviour in an island population of Savannah sparrows (Passerculus
sandwichensis) located on Kent Island in the Bay of Fundy.
Designing optimal conservation plans for migratory species
Each year, billions of dollars are spent on conserving and managing migratory
species worldwide. However, decisions on how to allocate fund for conservation is
largely based on ad-hoc approaches or simple ranking methods. Our research seeks
to integrate demographics and movement data across multiple stages of the annual
cycle to develop optimal conservation strategies for migratory species. We use both
theoretical- and empirical-based models to explore how various population
parameters influence resource allocation decisions.
Forensic population ecology
Forensic ecology takes advantage of intrinsic makers, such as stable isotopes, trace
elements, and DNA, in historical samples to examine past events related to
individual, population or community dynamics. As part of a project aimed at
understanding population declines in the Marbled murrelet (Brachyramphus
marmoratus) , we are using stable-nitrogen and -carbon isotopes to reconstruct the
diet of this threatened seabird over the past 100 years. Murrlets nest in mature
coastal forest but reside most their life at sea from Alaska to California and are listed
as threatened in Canada (COSEWIC). Causes of population decline are thought to
include the loss and fragmentation of forest habitat and increased mortality due to
over-fishing, climate change and other factors related to declines in the quality of
habitat at sea. Currently, we have analyzed the vast majority of available museums
samples from Murrelet specimens located between Puget Sound and southern
Alaska and dating as far back Captain Cook’s west coast voyage in 1778. Currently,
we are collected and analyzing museum specimens from Atlantic puffins (Fratercula
arctica) collected from Canada, Iceland and Scandinavia.
Behaviour and conservation
Isolation of habitat is thought to impede the movement of animals living in
fragmented landscapes. The effect of habitat isolation on the behaviour of animals,
however, is not well understood. Knowledge of how behaviour is affected by habitat
fragmentation is not only important for determining changes in per capita rates but
also for understanding how and why individual chose to settle in certain landscapes.
For example, we have show how patch size and the degree of isolated can inhibit
male and female Hooded warblers (a small songbird) from seeking extra-par
copulation's from neighbouring females. Previous work has shown that extra pair
copulations and extra-territorial behaviour is a widespread phenomenon in this
species and many other migratory birds. Inhibiting individuals from crossing gaps,
therefore, can disrupt social mating systems and result in individuals avoiding
certain landscapes or isolated patches. In the future, we will continue to research
the effect of fragmentation on movement by examining the effect of isolated on
parental care on tropical and temperate avian populations.
Selected Publications
Janssen, M.H., Arcese, P., Kyser, T.K., Bertram, D., Williams, T.D., McFarlaneTranquilla, L., and D.R. Norris. 2009. Pre-breeding diet quality and timing of
breeding in a threatened seabird, the Marbled murrelet. In press: Marine
Ornithology.
Sorenson, M.C., Hipfner, J.M., Kyser, T.K., and D.R. Norris. 2009. Carry-over effects in
a Pacific seabird: stable isotope evidence that non-breeding diet quality influences
reproductive success. In press: Journal of Animal Ecology.
Wunder, M.B., and D.R. Norris. 2008. Improved estimates of certainty in stableisotope-based methods for tracking migratory animals. Ecological Applications
18:549-559.
Wilson, S., D.R. Norris, A. Wilson, and P. Arcese. 2007. Experience and density affect
the ability of a temperate songbird to respond to future variation in climate.
Proceedings of the Royal Society, London: Biological Sciences 274:2669-2675.
Martin, T.M., I. Chades, P. Arcese, P.P. Marra, H.P. Possingham, and D.R. Norris. 2007.
Optimal conservation of migratory birds. Public Library of Science, One 2(8):e571.
Norris, D.R., P. Arcese, D. Preikshot, D.F., Bertram, and T.K. Kyser. 2007. Diet
reconstruction and historic population dynamics in a threatened seabird. Journal of
Applied Ecology 44:875-884.
Taylor, C.M., and D.R. Norris. 2007. Predicting conditions for migration: effects of
density-dependence and habitat quality. Biology Letters 3:280-283.
Norris, D.R., P.P. Marra, T.K. Kyser, L. M. Ratcliffe, and R. Montgomerie. 2007.
Continent-wide variation in feather colour of a migratory songbird in relation to
body condition and moulting locality. Biology Letters 3:16-19.
Norris, D.R., P.P. Marra, G.J. Bowen, L.M. Ratcliffe, J.A. Royle, and T.K. Kyser. 2006.
Migratory connectivity of a widely distributed Neotropical-Nearctic songbird.
Ornithological Monographs 61:14-28.
Norris, D.R., and C.M. Taylor. 2006. Predicting the consequences of carry-over effects
in migratory animals. Biology Letters 2:148-151.
Norris, D.R. 2005. Carry-over effects and habitat quality in migratory populations.
Oikos 109:176-186.
Norris, D.R., P.P. Marra, R. Montgomerie, T.K. Kyser, and L.M. Ratcliffe. 2004.
Reproductive effort, molting latitude and feather color in a migratory bird. Science
306:2249-2250.
Norris, D.R., P.P. Marra, T.K. Kyser, T.W. Sherry, and L.M. Ratcliffe. 2004. Tropical
winter habitat limits reproductive success in a long-distance migratory songbird.
Proceedings of the Royal Society, London: Biological Sciences 271:59-64.
Click here for a full list of publications
Teaching
Whether in the field or the classroom, my philosophy is to provide students with an
atmosphere that will allow them to enjoy the material and develop higher level
learning skills rather than simply regurgitation material. I strive to get students to
evaluate, analyze, and synthesize information while providing them with a solid
theoretical background. In the classroom, I rely partly on student participation and
peer learning. In the field, I allow students to develop and execute hypothesis-based
research on a wide range of topics in behaviour, as well as population and
community ecology.
Courses taught
ZOO*4070: Animal Behaviour
ZOO*4410: Field Ecology in Algonquin Park
Grad Students
If you are interested in any of the research areas outlined above, please feel free to
contact me via email and make sure to include a cover letter, CV, and unofficial
transcript. I am open to novel and creative research ideas and I worked closely with
my graduate students to develop and refine their thesis topics. Typically, my
students have a field component to their research but I will also supervise students
conducting purely theoretical work as well. I strongly encourage students to write a
series of publications that will eventually form the chapters of their thesis.
Current graduate students:
Mitchell, Greg (PhD)
Janssen, Michael (MSc)
Miller, Nathan (MSc)
Sheehy, Justin (MSc)
Links
Ecology @ Guelph [http://www.uoguelph.ca/~ecology/]
Queen’s Facility for Isotope Research [http://geol.queensu.ca/isotope_lab/]
Centre for Applied Conservation Research-UBC [http://cacr.forestry.ubc.ca/]
Center for Wildlife Ecology-SFU [http://www.sfu.ca/biology/wildberg/]