Associate Professor Department of Biology University of Western Ontario London, Ontario, N6A 5B7 CANADA Phone: (519) 850-2549 FAX: (519) 661-3935 lzanette@uwo.ca

Killam PDF, UBC, 1999-2001
Ph.D., University of New England, 1999
M.Sc., Queen's University, 1990
B.Sc., University of Toronto, 1988
         

Research Interests Graduate Opportunities Selected Publications

Volunteer Opportunities Song Sparrow Spotting

Website last updated 09 September, 2008

Overview

Dozens of species of songbirds have declined in abundance or disappeared altogether
from much of their historical range in association with large-scale habitat destruction,
and changes in land use, on every inhabited continent.  Rachel Carson’s warnings in the
early 1960’s that excessive pesticide use could result in a ‘silent spring’ highlighted the
effects of persistent toxic chemicals as a potential mechanism in these songbird declines.
By identifying a particular mechanism, Carson’s work was instrumental in changing
agricultural practices and thereby averting the disaster she foresaw.  Unfortunately, the
pattern of decline has continued.  Surprisingly, the mechanisms responsible for these
continued declines are not well understood.  The long-term goal of my research program
is to identify the mechanisms responsible for the global declines in songbird abundance.
Through a series of rigorously designed, large-scale, controlled field experiments, I am
testing the various mechanisms hypothesized to be responsible for these declines.
This research is already being cited as a model for the experimental approach to the study
of ecology and will have broad implications for the conservation of biodiversity.  As in
medicine, an accurate diagnosis is indispensable for both prevention and recovery.

Current Research

Synergistic effects of food and predators on the population viability of songbirds.

Most animals must continually balance the need for food against becoming food.  Hence,
food and predators are unlikely to have independent effects on demography.  Because
population level experiments on terrestrial vertebrates are rare, and bifactorial
experiments are rarer still, synergistic effects of food and predators on demography have
only recently been shown in mammals and have never before been demonstrated in birds.
My current research provides the first evidence of just such synergistic effects in birds.

These results confirm conclusions from my earlier work on the respective roles of
forest fragmentation, and Brown-headed Cowbirds, in songbird declines, and help to
explain why declines are both so common and so precipitous.  Since anthropogenic
disturbance both reduces food availability and increases predation, it follows that natural
systems must generally possess both more food and fewer predators.  When these natural
systems are disturbed, precipitous declines are to be expected if a there is a negative
synergism between food shortage and increased predation, and either food or predation
changes.  A fuller understanding of such synergistic effects is essential if we hope to
prevent further declines, and reverse existing ones.

Graduate student Marc Travers commutes to work

My current major research program involves an ongoing 2x2, manipulative food addition
plus natural predator reduction experiment on 14 populations of Song Sparrows
(Melospiza melodia).  Each site is home to about 7 territorial pairs.  Six sites are located
in Victoria, B.C., where predators are abundant, and the remaining 8 are located on
several small islands (in the adjacent Haro Strait), where predators are rare or absent.
From Feb.-Aug. food is added ad libitum to half (3) of the high predator and half (4) of
the low predator sites.  A single gravity fed feeder filled with a mixture of millet seed and
high protein pellets is located in the middle of each territory at the food supplemented
sites.  All 14 Song Sparrow populations are intensively monitored throughout the 7 mo.
breeding season.  Breeding success is established by finding every nest built by every
territorial pair as early as possible in the nesting cycle and conducting frequent nest
checks thereafter to accurately determine the pattern of nest failures and the
proximate cause (abandonment, starvation or predation).

Fed and control sites in low (Portland Isl.) and high (Victoria) predator areas

On average territories subject to the combined food addition + low  predator treatment
fledge almost twice (1.7 times) as many young as would be expected if the effects of
food and predators were independent and additive.  This effect (1.7 > additive)
is similar in scale to those (1.5-1.9 > additive) recently shown in mammals.

Balancing food and predator pressure induces chronic stress in songbirds.

Chronic physiological stress induced by the never-ending tension between finding food
and avoiding predators appears to be the proximate mechanism underlying the above
synergistic effects on demography.  The ‘chronic stress’ hypothesis predicts: 1) an
animal’s stress profile will be a simultaneous function of food and predator pressures
given the aforementioned tension; and 2) these inseparable effects on physiology will
produce inseparable effects on demography due to the resulting adverse health effects. 
Working with Prof. Michael Clinchy (UVIC), Prof. Rudy Boonstra (U of T) and Prof.
John Wingfield (U Washington) we have now documented the simultaneous food and
predator effects on measures of chronic stress predicted by the 'chronic stress'
hypothesis.  Chronic stress appears to provide the missing link between immediate
behavioural and longer-term demographic processes.
This work was featured in the Globe and Mail, National Post and on CBC webnews.

Professors Mike Clinchy and Rudy Boonstra stressing out on the Gulf Islands

Mobile Solar Video (MSV) systems for wildlife surveillance.

A chronic problem facing anyone studying the 90 % of vertebrates that are small and
secretive is that while the effect of predation is easily measured we rarely actually know
who the principal predators are.  The development in just the past few years of
miniaturized systems that allow us to ‘catch predators in the act’ is as significant an
innovation for ecology as the development of the microscope was for the study of
disease.  Technical constraints, however, have so limited the use of these systems that
only one study has generated enough data for statistical analyses.  While working with
me as a post-doc, and using funds from a Canada Foundation for Innovation (CFI) grant
on which I acted as PI, Prof. Michael Clinchy (UVIC) developed 8 Mobile Solar Video
(MSV) systems designed to permit 24 hr/day, continuous video surveillance of wildlife,
over a 20 ha area, at remote locations anywhere in Canada.  Prof. Clinchy's design
overcomes all of the constraints on earlier systems.  Each MSV consists of an enclosure
housing a digital video recorder (DVR) and batteries, from which cables up to 250 m in
length radiate out to up to 8 separate cameras and a photovoltaic (solar) power array.

Professor Clinchy and his Mobile Solar Video (MSV) system for wildlife surveillance

toss.  When the cowbird
leaves, there are 3 eggs.  So in less than 10 seconds the cowbird has punctured a
sparrow egg and laid her own all while being attacked by the song sparrow mom.

Using the DVR's programmable motion detection capabilities only visits to the nest by
parents or predators are recorded, eliminating the need to fast forward through hours and
hours of video of sleeping birds.

The DVR (left) is built into a size 1520 Pelican case.  It can be programmed using a small monitor
(in it's own Pelican case, upper right photo) and the DVR's built-in controls (circular buttons).
The bottom right photo shows a screenshot of the monitor filming 7 nests simultaneously.

Cowbird Research

Brown-headed Cowbirds skew host offspring sex ratios

Brown-headed Cowbirds (Molothrus ater) do not build their own nests but instead
lay their eggs in the nests of other species.  Because Cowbirds often destroy the
eggs or nestlings of the host to ensure that their own young has fewer competitors in
the nest, they may have the same effect on host numbers as other more conventional
predators.  Continentally, Cowbird numbers have increased in association with land
clearance for agriculture.  Many U.S. states presently invest millions in Cowbird
eradication.  Debate over the efficacy of these programs has persisted because the
evidence to date has all been correlational and circumstantial.  I collaborated in
conducting the very first large-scale, spatially and temporally replicated, controlled
Cowbird removal experiment in North America.  This research showed that adult
Cowbirds can reduce the annual reproductive success of their hosts by 50 %.  New
research in my lab has shown that the presence of Cowbird nestlings causes a
further 50 % loss of female host nestlings!  This new research was featured in Science
(immediately below) and I was interviewed concerning it by Bob McDonald on the
21 May, 2005, broadcast of CBC's radio's Quirks and Quarks.

Feature item in the Editor's Choice section of Science (2005, Vol. 308, p. 927).

Forest Fragmentation Research

Food supply, nest predation and songbird demography in forest fragments.

Many species of songbirds that do well when occupying only a few hectares within an
intact forest decline and disappear from similarly sized remnants.  Such ‘area-sensitive’
species often only persist in remnants that are much larger than would be expected given
their habitat requirements within intact forests.  I conducted a large-scale, spatially and
temporally replicated, mensurative experiment designed to test the joint effects of food
and predation on the demography of an area-sensitive songbird inhabiting forest
fragments of different size.  I compared three independent indices of food availability,
and three measures of predation, as well as monitoring seasonal fecundity and adult
female survival among Eastern Yellow Robins breeding in two small, and two large
forest fragments, set within an agricultural landscape in southeastern Australia.  All three
indices of food availability were indicative of food shortage in smaller fragments.  These
novel results have attracted considerable attention (see links to E.N.N. Report below).

Environmental News Network Report: "Deforestation may be starving songbirds"

Eastern Yellow Robin (Eopsaltria australis)

Graduate Opportunities

I am looking for both Ph.D. and M.Sc. students to work on a variety of projects within
the context of my current major research program.  If you find the kinds of questions my
research addresses compelling, please fill in my Potential Grad Student Questionnaire
and forward it to me (via e-mail) together with a brief (up to 2 page) outline of the kind
of research you envisage conducting in my lab.  Please also send your transcripts as an
attachment.  Transcripts from the web are fine (i.e., I do not require official transcripts).

View from Shell Beach (Control, bottom left Portland Isl. map)

Zanette, L., Clinchy, M., and Smith, J. N. M.  2006.  Combined food and predator
     effects on songbird nest survival and annual reproductive success: results from a
     bi-factorial experiment.  Oecologia, 147: 632-640.

MacDonald, I. F., Kempster, B., Zanette, L., and MacDougall-Shackleton, S. A.  2006. 
     Early nutritional stress impairs development of a song-control brain region in both male
     and female juvenile song sparrows (Melospiza melodia) at the onset of song learning. 
     Proc. R. Soc. B, 273: 2559-2564.
     (New Scientist feature "Hungry sparrows sing the saddest songs")

Zanette, L., MacDougall-Shakleton, E., Clinchy, M., and Smith, J. N. M.  2005.
     Brown-headed cowbirds skew host offspring sex ratios.  Ecology, 86: 815-820.
     (Quirks and Quarks interview with Bob McDonald, 21 May 2005)

Clinchy, M., Zanette, L., Boonstra, R., Wingfield, J. C., and Smith, J. N. M.  2004. 
     Balancing food and predator pressure induces chronic stress in songbirds. 
     Proc. R. Soc. B, 271: 2473-2479.
     (See features in the Globe and Mail, National Post and on CBC webnews).

Zanette, L., Smith, J. N. M., van Oort, H., and Clinchy, M.  2003.  Synergistic
     effects of food and predators on annual reproductive success in song sparrows.  
     Proc. R. Soc. B, 270: 799-803.

Smith, J. N. M., Taitt, M. J. and Zanette, L., and Myers-Smith, I. H. 2003.  How do
     Brown-headed Cowbirds (Molothrus ater) cause nest failures in Song Sparrows
     (Melospiza melodia)? A removal experiment. Auk, 120: 772-783.

Smith, J. N. M., Taitt, M. J. and Zanette, L.  2002.  Removing Brown-headed
     Cowbirds increases seasonal fecundity and population growth in Song Sparrows.
     Ecology, 83: 3037-3047.

Zanette, L.  2001.  What do artificial nests tell us about nest predation?
     Biological Conservation, 103: 323-329.

Zanette, L.  2001.  Indicators of habitat quality and the reproductive output of a forest
     songbird in small and large fragments. Journal of Avian Biology, 32: 38-46.

Zanette, L.  2000.  Fragment size and the demography of an area-sensitive songbird.
     Journal of Animal Ecology, 69: 458-470.

Zanette, L., and Jenkins, B.  2000.  Nesting success and nest predators in forest
     fragments: a study using real and artificial nests. Auk, 117: 445-454.

Zanette, L., Doyle, P., and Tremont, S. M.  2000.  Food shortage in small fragments:
     evidence from an area-sensitive passerine. Ecology, 81: 1654-1666. 
     (E.S.A. Press Release)

Leonard, M. L., and Zanette, L.  1998.  Female mate choice and male behaviour
     in domestic fowl.  Animal Behaviour, 56: 1099-1105. 
     (Nature Science Update)

Zanette, L., and Ratcliffe, L. M.  1994.  Social rank influences conspicuous behaviour
     by black-capped chickadees, Parus atricapillus. Animal Behaviour, 48: 119-127.
     ("Watching the hunted", Bird Watcher's Digest)

Herz, R. S., Zanette, L., and Sherry, D. F.  1994.  Spatial cues for cache retrieval in
     black-capped chickadees.  Animal Behaviour, 48: 343-351.