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Jolyon Troscianko
Tel: +44 (0)
1223 334 430
Fax: +44 (0) 1223 336 676
Email: jt at jolyon.co.uk
Position held:
Research Assistant (to Martin Stevens)
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| Current
Research |
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I
shall be working on projects covering sensory ecology, animal colouration
and bird vision with Martin Stevens.
Our research will investigate how various anti-predator colouration
strategies such as camouflage, warning signals, motion dazzle and
eyespots interact with the predators’ vision, and how they work
together to evade predation. This research will use woodland birds
as wild predators and artificially generated moths as prey, but will
also use humans as ‘predators’ shown computer simulations
of prey with different colouration and motion strategies.
Using brood parasitism as a model system I will work with Claire
Spottiswoode to investigate how parasitic chicks successfully
‘trick’ their host parents into raising them using visual
mimicry at a number of developmental stages, from egg-shells to fledging
chick.
Further work will focus on the properties of avian vision to help
us understand how the different signalling strategies of prey have
evolved in response to the receivers’ visual system.
My responsibilities also include the supervision of undergraduate
projects in the lab and field.
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| Previous
Research |
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My
PhD at Birmingham University focused on the fascinating tool-use
behaviour of New Caledonian crows, studying various aspects
of their behavioural ecology, morphology and cognition. These
crows often use tools to extract wood-boring beetle larvae from
deadwood, but tool-use proficiency can take years to develop
in young crows. Using novel filming methods in the wild I found
that the crows can vary their tool probing strategies in response
to the larva’s orientation and weight, suggesting that
this apparently simple tool-use task requires costly investment
whilst individuals develop subtle probing strategies. This study
also suggested visual feedback could be important during tool-use.
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Holding a tool in the bill places awkward physical constraints
on watching the tool-tip – a problem that primates don’t
encounter. I found that New Caledonian crows have a unique
visual field that combines with their peculiarly straight
bill, enabling them to see directly down the tool into a small
hole. All other corvids have curved bills – which are
ideal for probing into substrates and tearing at carrion –
but would project the tool down into a narrow area of their
visual field so they wouldn’t be able to see what they’re
doing. To my knowledge this represents the only case of morphological
adaptations for tool-use outside of the human hand, and could
provide a simple explanation for the scarcity of tool-use
in intelligent corvids.
Above:
A still-frame from video footage of a captive NC crow probing
into a tube for a mealworm, with the eyes apparently oriented
forwards and looking down the tube.
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Above: (a) Photograph of an unmarked wild crow ‘fishing’
a larva from a larva-cam log. (b) Still frame of footage from
inside the log; the larva is positioned mandibles-up, shown
interacting with a tool-tip. Two mirrors behind either side
of the central tube provide an uninterrupted view of the tool-tip
and larva from all around.
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In
order to understand how tool-use evolved in New Caledonian crows we
must first ascertain the ecological importance of the behaviour. Stable
isotope analysis revealed how larvae and nuts make up a substantial
component of their daily nutritional intake, and our previous study
using motion-triggered video cameras reveals that the majority of
these larvae are extracted using tools. However, observing the tool-use
of elusive wild New Caledonian crows is exceedingly difficult away
from feeding tables or sites of high activity, indeed we know almost
nothing about the tool-use ecology of crows in the humid forests.
I therefore helped to develop a new type of video camera that grants
us a unique “birds’ eye view”, which will allow
us to observe their humid forest behaviour.
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Above: Schematic
showing how we attach ‘crow-cam’ units to the tail so
that the camera films through the bird’s legs. |
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| Prior
to my PhD I worked on the biomechanics of insect flight, and the rate
of evolution and gene loss in an annelid worm during my Biosciences
MSc at Oxford University. I also researched the conspicuousness of
woodland bird species under different lighting regimes during my BA
in Biology at Oxford. |
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| Publications |
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- Rutz, C.
Bluff, L.A. Reed, N. Troscianko, J. Newton, J. Inger, R. Kacelnik,
A. & Bearhop, S. (2010). The Ecological Significance of Tool
Use in New Caledonian Crows — Science: 329, 1523-1526
- Bluff, L.
A., Troscianko, J., Weir, A. A. S., Kacelnik, A. & Rutz, C.
(2010). Tool use by wild New Caledonian crows Corvus moneduloides
at natural foraging sites — Proceedings of the Royal
Society B: Biological Sciences 277, 1377-1385
- Takahashi,
T., McDougall, C., Troscianko, J., Chen, W. C., Jayaraman-Nagarajan,
A., Shimeld, S. M. & Ferrier, D. E. K. (2009). An EST screen
from the annelid Pomatoceros lamarckii reveals patterns of gene
loss and gain in animals. — BMC Evolutionary Biology
9, 240.
- Troscianko,
J., Bluff, L. A. & Rutz, C. (2008). Grass-stem tool use in
New Caledonian Crows Corvus moneduloides. — Ardea
96, 283-285.
- Lovell, P.
G., Tolhurst, D. J., Parraga, C. A., Baddeley, R., Leonards, U.
& Troscianko, J. (2005a). Stability of the color-opponent
signals under changes of illuminant in natural scenes. —
Journal of the Optical Society of America a-Optics Image Science
and Vision 22, 2060-2071.
- Lovell, P.
G., Tolhurst, D. J., Parraga, C. A., Baddeley, R. J., Leonards,
U., Troscianko, J. & Troscianko, T. (2005b). Opponent channel
responses to changes in the illuminant of natural scenes for primates
and birds. — Perception 34, 59-59.
- Troscianko,
T., Parraga, C. A., Leonards, U., Baddeley, R. J., Troscianko,
J. & Tolhurst, D. J. (2003). Leaves, fruit, shadows, and lighting
in kibale forest, Uganda. — Perception 32, 51-51.
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