Social responses without early experience: Australian brush-turkey chicks use specific visual cues to aggregate with conspecifics
Animal Behaviour Laboratory, Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia
* Author for correspondence (e-mail: ann{at}galliform.bhs.mq.edu.au)
Accepted 1 April 2004
![]() |
Summary |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: megapode, social aggregation, imprinting, species recognition, brood parasite, behavioural development
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Three groups of birds, however, reveal that other developmental pathways
can evolve. Interspecific brood parasites, such as cuckoos and cowbirds
(Molothrus ater), are incubated and raised by members of other
species. Black-headed ducks (Heteronetta atricapilla) are incubated
by heterospecifics but live independently of their foster parents soon after
hatching (Weller, 1968).
Megapodes also receive no parental care, but in this case the heat required
for incubation is derived from inanimate sources, depriving the chicks of any
potential social interactions.
The development of social attachments in brood parasites has been the focus
of much study (Hamilton and Orians,
1965; West and King,
1987
; Soler and Soler,
1999
; Hauber et al.,
2000
; Payne et al.,
2000
; Hauber and Sherman,
2001
; Hauber,
2002
), but less attention has been paid to this aspect of megapode
ontogeny. Megapodes leave the incubation of their eggs to solar heat,
geothermal heat in burrows or the heat produced by microbial decomposition in
mounds of leaf litter (Jones et al.,
1995
). Their highly precocial chicks dig themselves out of their
underground nest and never form bonds with their parents
(Jones et al., 1995
;
Göth, 2001b
).
Opportunities for imprinting thus do not occur. Wong
(1999
) repeated the classic
experiments designed to test imprinting in other birds
(Hess, 1958
) and found that,
in a circular runway, young chickens (Gallus gallus domesticus)
followed a ball that was moved away from them, and thereby imprinted on it,
but hatchlings of the Australian brush-turkey (Alectura lathami Gray;
henceforth brush-turkey) showed no such response.
Recent work on brush-turkey chicks the only megapode species
studied in detail also suggests that they are unlikely to imprint on
similar-aged conspecifics during a sensitive period after hatching.
Brush-turkeys hatch asynchronously and spend, on average, 40 h buried in the
incubation mound before dispersing
(Göth, 2002). Thereafter,
they usually live on their own while foraging in the leaf litter beneath
protective thickets (Göth and Vogel,
2003
). Brush-turkey chicks are capable of finding adequate food
alone (Göth and Proctor,
2002
) and of responding appropriately to predators without prior
experience (Göth, 2001a
).
These attributes enable them to survive without assistance from others. In a
recent radio-tracking study, free-ranging brush-turkey chicks were seen
feeding near at least one other chick in 6% of all encounters (N=166
encounters with 31 chicks, aged 2 days to 4 weeks;
Göth and Jones, 2003
).
Chicks older than 100 days are seen in groups more often
(Jones, 1988
). Brush-turkeys
hence first aggregate with conspecifics at an unpredictable age, between two
days and several weeks following emergence from the incubation mound.
A recent study in which chicks were kept in a large outdoor aviary revealed
that social responses to similar-aged conspecifics were apparent from as early
as two days. All of the behaviour patterns found in older chicks were present
in hatchlings, and these did not change appreciably with age
(Göth and Jones, 2003).
In addition, hatchlings stayed close together (median distance 0.1 m while
feeding and 0.34 m while resting), despite the large size (76 m2)
of the aviary (Göth and Jones,
2003
). Brush-turkey chicks thus have competent social behaviour
when they first encounter a conspecific, suggesting that the mechanism
responsible for aggregation is largely independent of early social experience.
What features of a conspecific are involved in evoking this aggregation
response? The aim of this study was to evaluate the role of visual cues,
including both morphology and movement.
Our general approach was based upon recent work with cowbirds (Hauber et
al., 2000,
2001
). These brood parasites
face a similar developmental challenge in that they grow up without parents or
siblings. Imprinting on the features of a heterospecific foster parent would
lead to subsequent errors in species recognition and mate choice
(Hauber and Sherman, 2001
).
Young cowbirds seem to rely instead upon self-referent phenotype matching, a
mechanism in which they learn salient aspects of their own phenotype, such as
calls or plumage colour, and then match the appropriate features of
conspecifics to these (Hauber et al.,
2000
,
2001
).
We tested whether two particular aspects of the brush-turkeys' phenotype
affect social aggregation: `colour' (i.e. the spectral shape of the light
reflectance function) and behaviour, in particular pecking movements. Recent
work has shown that plumage colour plays an important role in many avian
social interactions (Hill,
1991; Bennett et al.,
1997
; Cuthill et al.,
1999
; Hunt et al.,
2001
). Classic studies established that galliform chicks are
particularly responsive to maternal pecking
(Turner, 1965
), suggesting
that this particular motor pattern might also be important with similar-aged
companions. We did not consider vocalisations a likely cue because
brush-turkey hatchlings rarely call
(Göth and Jones, 2003
).
This is the first investigation of the way in which any megapode aggregates
with conspecifics. It forms part of a series of experiments exploring whether
such mechanisms are convergent across different groups with the shared
life-history property of having no reliable opportunity to learn
species-specific characteristics from others.
![]() |
General methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Procedure
Tests took place in a large, T-shaped, outdoor aviary
(Fig. 1), in which the chicks
were presented with a simultaneous choice between two stimuli in opposite
arms. The aviary was constructed in a forest (Macquarie University Fauna
Park), which resembled the natural habitat of brush-turkeys. Chicks are very
wary and are most likely to behave naturally in such an environment
(Göth and Jones, 2003).
The centre of the aviary contained a covered area (30 cm high), which was the
section from which tests were begun (Fig.
1). Chicks entered the choice arms by crossing a line delineated
by inconspicuous markers on the ground. A very fine green mesh `division net'
separated the central compartment from the two arms containing the stimuli
(Fig. 1). The floor of the test
aviary was covered with sand, pebbles and leaf litter. Observations were
conducted from a hide directly opposite the covered area and connected to the
test arena via a sliding door
(Fig. 1). Water and seeds were
provided beneath the covered area.
|
Tests were begun by placing a chick under the covered area, after which the
observer slowly crawled back to the hide and closed the sliding door. Chicks
usually crouched during this 1016 s-long procedure and afterward
remained still for a period of up to 10 min. Such immobility is the typical
response of brush-turkey chicks to predators
(Göth, 2001a); it usually
ended when the chick stood up and started to scan its surroundings or peck at
the ground. Of the 96 chicks tested, 91 showed this behavioural sequence of
crouching and scanning/pecking and it can thus be inferred that they made an
active choice when finally leaving the covered area to enter one of the choice
arms. Four chicks ran into a choice arm while the observer was still
retreating to the hide. These were excluded from the analysis because their
behaviour seemed more likely to be an antipredator response than social
aggregation with the stimulus. One chick did not leave the covered area for
one hour and was also excluded from the analysis. Tests were conducted in the
morning (07:00 h11:00 h) on fine days, except for three that had to be
postponed until the afternoon due to rain. Each chick was tested only once and
experienced a single pair of stimuli. Stimuli were assigned to the choice arms
in a constrained random sequence, such that they were presented an equal
number of times on the left and right side. Tests lasted for one hour.
All procedures were approved by the Macquarie University Animal Ethics Committee (Protocol no 2002/013) and the New South Wales National Parks and Wildlife Service (Licence no. S10473).
Scores and analysis
Four video cameras covered the choice arms of the aviary
(Fig. 1). These were connected
to a multi-channel monitor in the hide, which the observer relied upon
whenever the chick was in a blind corner. At all other times, she used direct
observation and recorded continuously with a stopwatch the time that the
chicks spent in the centre area and in each of the two choice arms. Half of
the observations were conducted by A.G., the other half by a research
assistant. For analysis, we converted the time recorded in each choice arm to
a percentage of the total time spent in both choice arms. Exploratory analysis
revealed considerable heterogeneity of variance, and data transformation did
not generate normality. We thus adopted the non-parametric Wilcoxon
signed-rank test for all pairwise comparisons, as this is sensitive to both
the direction and magnitude of differences
(Siegel and Castellan, 1988).
Tests were one-tailed because we had a priori predictions about chick
preference in every case (see below).
Pilot test
We began with a test designed to verify that the aggregation response was
expressed normally in the T-shaped aviary. Six chicks were each presented with
a simultaneous choice between a conspecific in one choice arm and a box of
similar colour and dimensions (17x10x13 cm) in the other. We
predicted that the box would be approached less often than the live chick. The
stimulus chick was 23 days old and provided with food and water.
Stimulus chicks were moved into the area behind the division net at least half
an hour before the test. They appeared calm, moved around freely and showed
the full range of natural chick behaviour. A different stimulus chick was
presented in each test. Four of the five tested chicks spent 100% of their
time in the choice arm containing the stimulus chick, one chick spent 97.5% of
its time near the stimulus chick and the remaining time near the box. As a
group, chicks approached the stimulus chick significantly more often than the
box (Wilcoxon test, z=2.33, P=0.01, one-tailed,
N=6). This strong spontaneous preference for another chick over a
size-matched object of equal novelty provides the basis for subsequent
analyses designed to identify the features responsible for the aggregation
response.
![]() |
Behaviour as a cue evoking social aggregation |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
We tested movement preferences using two comparisons: (1) a pecking versus a static robot and (2) a pecking versus a scanning robot. The first experiment was designed to detect a general preference for realistic movement, while the second evaluated the specificity of response by comparing pecking with a control movement of similar amplitude but in an orthogonal plane. We used one-tailed tests because we predicted that the pecking robot would be more attractive than either the static or the scanning robot. These predictions were based both upon our own previous studies of brush-turkey chicks and on published accounts of general galliform behaviour.
Brush-turkey chicks held in groups often approach a pecking companion and
then fixate upon the food it is feeding on; such a response is less likely to
be evoked by other types of conspecific behaviour
(Göth and Jones, 2003).
In addition, classic studies have established that galliform chicks in general
are particularly responsive to maternal pecking
(Turner, 1965
), suggesting
that in megapodes (which do not form bonds with their parents) this particular
motor pattern might be important with similar-aged companions. There are also
functional reasons for predicting that the pecking model should be more
salient. Brush-turkey hatchlings face an unusual challenge: they have to find
food on their own, unaided by their parents. A pecking conspecific is likely
to indicate a source of food, so that preferential approach will likely
enhance foraging success. Finally, sensitivity to specific motor patterns is
ubiquitous in vertebrates because it helps animals to select the small sub-set
of visual motion cues that are functionally important and to filter these from
the many irrelevant events occurring in the environment
(Nakayama and Loomis, 1974
;
Fleishman, 1992
). We predicted
that pecking movements would be responded to in this way.
Methods
The robots were constructed from taxidermally prepared mounts of 3-day-old
chicks that had died naturally. They contained a servo motor (`Nagro'; Grand
Wing Servo-tech, Hsichih, Taipei, Japan) that was operated by radio control
(`Attack' 2-channel system; Futaba Bioengineering, Irvine, CA, USA). The motor
moved the chick body in either a vertical (pecking movement) or horizontal
(scanning movement) plane, while the feet remained stationary
(Fig. 2). During pecking, the
head moved from a static position (in which the beak was pointing forward),
downward until it made contact with the ground
(Fig. 2AC). During
scanning, the robot performed horizontal movements of the whole body, through
an angle of approximately 45° to either side of the resting position
(Fig. 2DF). Three
pecking robots were used randomly in the choice tests (including the `filter
tests' described below), and one scanning robot was presented in the
peckingscanning comparisons. The static control model was mounted in a
neutral posture, with the head horizontal, the beak pointing forward and the
feathers sleeked.
|
An assistant moved the robot via remote control at the beginning of each test, while the chick was being placed under the covered area by the observer. Robots were moved in bouts of 10 pecking or scanning movements with a total duration of 6.58.0 s, which made up a single `stimulus event'. The intervals between stimulus events were varied between 1 min and 4 min to minimize habituation. In tests that involved the presentation of two robots, both were moved simultaneously.
Results
When given the choice between static and pecking robot models of
similar-aged conspecifics, chicks spent significantly more time near the
pecking robot (Fig. 3A;
Wilcoxon test, z=1.79, P=0.042, one-tailed,
N=15). Chicks also significantly preferred the pecking robot over the
scanning robot (Fig. 3B;
Wilcoxon test, z=1.80, P=0.036, one-tailed,
N=11). This latter result suggests a degree of specificity in the
aggregation response. Chicks seem to have been sensitive to the plane of
movement not just to its presence or absence.
|
![]() |
Body colour as a cue evoking social aggregation |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The use of colour filters allowed us to make global changes to the colour
of the whole robot by altering the spectral shape of ambient light. This
method of colour manipulation has been widely adopted in mate choice
experiments with birds (Hill,
1991; Bennett et al.,
1996
,
1997
;
Cuthill et al., 1999
; Hunt et
al., 1999
,
2001
). Filters were mounted
horizontally above the robot chicks, on a frame 35 cm high, 72 cm wide and 72
cm deep. We adopted this technique in preference to a vertically mounted
filter in front of the robot stimulus, as this would have changed the overall
light conditions in the choice arm, including the background
(Bright and Waas, 2002
). The
overhead filters only affected the light environment in a 72 cm-wide area
centred upon the robot and caused no change in the light environment in the
remaining area of the choice arm, which was 3 m wide.
Methods
Colour manipulation followed methods described by Hunt et al.
(2001) and involved four types
of filters that each blocked a different waveband of the bird-visible spectrum
at rates of 9599%. (1) UV (Rosco UV 311413) blocked UV below 390 nm;
(2) SW (Rosco E 015) blocked short-wave at 380480 nm; (3) MW (Rosco E
028) blocked medium-wave at 500550 nm and (4) LW (Rosco E 115) blocked
long-wave at 560660 nm. The neutral density filter (Rosco E 00)
provided a matched reduction in quantal flux uniformly over the range between
300 and 700 nm. The wavebands removed by the SW, MW and LW filters match as
closely as possible the spectral sensitivity of the four cone types known for
galliforms; the UV filter was added because some body regions were found to
strongly reflect in the UV (see Results).
Tests with coloured filters were conducted outdoors under natural light.
Overhead illumination was therefore not as uniform and constant as in
laboratory tests (e.g. Bennett et al.,
1996; Hunt et al.,
2001
). The prevailing light environment can have profound effects
on the perception of colour signals
(Endler, 1993a
;
Bennett et al., 1997
). To
account for such effects, we measured the radiance spectra of three body
regions of the robot chicks under each type of filter and under three
different light conditions that were experienced during tests: (1) full sun,
with bright sky; (2) overcast, with cloud-covered sky; (3) partly overcast and
partly sunny. Measurements were conducted with a USB2000 Miniature Fibre Optic
Spectrometer (Ocean Optics, Dunedin, FL, USA) and a collimating lens (74-UV;
Ocean Optics). Results suggest that changing light conditions caused the
expected variation in the radiance curves obtained but that the four
treatments remained clearly distinct (Fig.
4).
|
In addition, we measured the reflectance of five body regions of 10 live chicks using a two-fibre probe, held at 45° to the sample's surface, with illumination from an internal deuteriumtungsten light (Light Mini D2T; Ocean Optics). Four randomly located measurements were taken within each body region of both robots and live chicks. The obtained spectra were the reflectance of the sample relative to that of a white WS-1 diffuse reflectance standard.
For analysis, radiance and reflectance spectra were averaged from 15 scans. Data were initially collected over the range 300800 nm. We then calculated the median value at 5 nm intervals from 320 to 700 nm, across the four randomly located measurements. Data were normalized by dividing all values by the highest value obtained, and the median, 1st and 3rd quartiles were then calculated for each interval.
Results
The effect of filter treatments on the chicks' preference for a robot
conspecific varied with spectral region
(Fig. 5AD). When UV and
SW radiance were removed from the robot, chicks spent significantly more time
in the choice arm containing a control robot that reflected in all wavelengths
(Wilcoxon tests; UV, z=2.0, P=0.01; SW,
z=1.67, P=0.048; both N=15 and one-tailed).
By contrast, removal of MW and LW radiance did not have a significant
detrimental effect on the attractiveness of the robot (Wilcoxon tests; MW,
z=0.60, P=0.28, N=15; LW,
z=1.38, P=0.09, N=14; both one-tailed).
|
Fig. 6 illustrates reflectance spectra from five body regions of live chicks. While the back, head and wing show the expected curve for brown colour, a surprisingly strong peak for UV and SW reflectance was found on the beak and especially the legs.
|
![]() |
Behavioural responses to the robot models |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods
High-resolution footage of behaviour was obtained by tracking each chick
with a digital colour video camcorder (Panasonic NV-DS 15). Subsequent
analyses of recorded footage yielded frequency scores for the first behaviour
that occurred in response to each stimulus event (bout of 10 robot pecking
movements). Social behaviour in the choice arm was assigned to one of the
following six categories:
The frequency of each of these behaviours was analysed separately for each of the first 10 stimulus events. To obtain a sufficient sample size, we pooled data from all robot tests. Analyses thus reveal the extent to which pecking robots were responded to as a social companion; they do not permit fine-grained comparisons among treatments, for which we had insufficient power. To evaluate whether chick behaviour varied over time, a Friedman non-parametric analysis of variance (ANOVA) was used for each type of response.
Results
Most chick responses to the robot were unambiguously social. Approach was
the most common social behaviour (25%), followed by pecking at the ground
(22%) and pushing against the division net (7%; values calculated from all
responses to all stimulus events experienced by the chicks in the movement and
colour experiments). Withdrawal represented only 14% of the responses, while
31% of stimulus events evoked no response.
There are some indications that the chicks' responses to the moving robot
might have habituated over time, although the pattern is mixed and not all
behaviours were affected (Fig.
7). The frequency of pecking decreased significantly with
successive stimulus events (Friedman ANOVA, 2=21.85,
P=0.009, d.f.=9), suggesting a reduction in aggregation response, but
the probability of withdrawal was also reduced (Friedman ANOVA,
2=28.21, P=0.001, d.f.=9), which is consistent with
some chicks becoming less fearful over time. The frequency of no response
increased significantly over the test (Friedman ANOVA,
2=21.46, P=0.011, d.f.=9). However, the two remaining
social behaviours, approach and pushing, occurred in response to all stimulus
events, and their frequencies did not change significantly over time (Friedman
ANOVAs, approach
2=8.23, P=0.51, d.f.=9; pushing
2=2.87, P=0.97, d.f.=9).
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Pecking movements may be particularly suitable cues for evoking approach
behaviour. Many signals used in animal interactions are defined by movement.
This is true in contexts as diverse as opponent assessment, mate choice,
pursuit deterrence and alarm signalling (summary in
Peters et al., 2002). Animals
have thus generally evolved high sensitivity to specific movement patterns
that are functionally important (Nakayama
and Loomis, 1974
; Fleishman,
1992
). Responding to pecking movement has a likely functional
benefit, as this behaviour can indicate a potential food source. Brush-turkey
chicks are omnivorous. They hatch with a general tendency to respond to some
common features of food objects, such as contrast, movement and reflective
surfaces, and while trial and error is initially important, they successfully
aim their pecks at edible items soon after hatching
(Göth and Proctor, 2002
).
A pecking conspecific indicating food might speed up the transition from trial
and error searching to more selective pecking through social transmission of
food-type preferences (Galef,
1993
), or it could simply stimulate foraging more generally
through social facilitation (Keeling and
Hurnik, 1993
). In domestic chickens, Gallus gallus
domesticus, young chicks respond strongly to a pecking model of a hen
(Turner, 1965
). Megapode
chicks do not form bonds with their parents but instead show this
predisposition in response to conspecific chicks of similar age. These feed on
similar-sized food small invertebrates, fruit and seeds while
adults, which weigh approximately 2 kg, search for much larger items (A.G.,
unpublished data).
We next consider the issue of why brush-turkeys might respond selectively
to a particular spectral region. In this context, it is important to note that
we treat the visual attributes mediating approach and social behaviour as
cues, rather than signals (review in
Bradbury and Vehrencamp, 1998).
Specifically, we do not yet know enough about the costs and benefits
(Seeley, 1989
) or the
evolutionary history of these traits
(Hasson, 1997
) to conclude
that they function as signals in the strict sense. Nevertheless, recent work
on sensory processes, much of it undertaken to explore signal design, provides
valuable insights concerning conspicuousness.
The relative importance of shorter wavelengths is likely to be the product
of both habitat transmission and sensory tuning (Endler,
1992,
1993b
;
Boughman, 2002
). Whether a
particular colouration appears conspicuous to potential receivers depends upon
the light environment and natural background against which it is usually seen
(Endler, 1993a
;
Endler and Basolo, 1998
).
Brush-turkey chicks typically inhabit thickets, either in the understorey or
at the rainforest edge (Göth and
Vogel, 2003
). In such habitats, short wavelengths are common in
natural light, such as that in woodland shade, small or large gaps in the
canopy, or in cloudy conditions, while they are rare in leaves and leaf litter
(Endler, 1993a
;
Andersson et al., 1998
). This
latter vegetation type is the typical visual background against which chicks
are viewed by conspecifics, and short wavelength reflectance is thus a good
way to produce high visual contrast.
Recent studies have revealed much about the way in which the avian retina
responds to visual stimuli (e.g. Endler,
1990; Bennett and Cuthill,
1994
; Osorio et al.,
1999
; Hart, 2001
;
Hunt et al., 2001
). The exact
spectral sensitivity of brush-turkey cone cells is not known, but it most
likely resembles that of other galliforms, such as the domestic chicken. This
is indicated by a preliminary study of brush-turkey retinas (N. Hart, personal
communication), as well as recent findings by Odeen and Hastad
(2003
). In the chicken, four
cone visual pigments have been identified, with mean peak absorbance at
417420 nm (violet), 453470 nm (short-wave), 507540 nm
(medium-wave) and 571600 nm (long-wave)
(Bowmaker et al., 1997
;
Osorio et al., 1999
). The
sensitivity of the brush-turkey's cone cells should thus have been covered by
the short-, medium- and long-wave filters used in the present study. The UV
filter did not precisely match the peak sensitivity of any cone type but it is
likely to have filtered out wavelengths falling into the lower part of the
sensitivity range of the short-wave sensitive cone. Furthermore, the violet
cones can also detect long-wavelength UV, from 360 to 400 nm
(Odeen and Hastad, 2003
).
Signal design is influenced not only by the sensory properties of
conspecifics but also by those of eavesdroppers, such as predators
(Endler and Basolo, 1998).
Selection for efficient communication at minimal risk has produced signals
that exploit `private channels' in some species
(Cummings et al., 2003
). The
natural predators of brush-turkey chicks are raptors, tree goannas
(Varanus varius), snakes and quolls (Dasyurus spp.)
(Göth and Vogel, 2002
).
One remarkable finding of this study was that the chicks' legs reflected
strongly in the UV and short-wave ranges
(Fig. 6). Birds of prey
typically have a similar spectral sensitivity to megapodes
(Odeen and Hastad, 2003
) but,
when flying overhead, they are unlikely to spot the legs of a chick, as these
will be well hidden beneath the dull brown body. Most mammalian predators are
effectively blind in the UV (Jacobs,
1993
), although goannas and snakes can perceive these wavelengths
(Husband and Shimizu, 2001
).
Taken together, this pattern of results is consistent with the idea that
brush-turkeys make use of a cue that is conspicuous to conspecifics
and hence effective in mediating an aggregation response but concealed
from important classes of predators, including raptors and mammals.
Legs, and to a lesser extent beaks, may be particularly suitable body
regions for an aggregation cue for a second reason. Chicks grow rapidly and
start replacing their brown hatching plumage with black feathers during the
third week of life (Wong,
1999). Basing a cue on ephemeral plumage colour would hence seem
less adaptive than using the colour of the legs, which is stable throughout
development.
In summary, our results suggest that the morphological cues important in
social aggregation in Australian brush-turkeys are found at short wavelengths.
Future experiments will involve selective manipulation of the UV components of
body coloration to determine whether this is necessary for a behavioural
response. Recent studies with birds suggest that UV reflectance is important
in a range of contexts, including foraging
(Cuthill et al., 2000) and
mate choice (Maier, 1994
;
Bennett et al., 1996
,
1997
;
Andersson and Amundsen, 1997
;
Hunt et al., 1997
,
1999
), although there is some
controversy over whether this spectral region should be considered `special'
(Hunt et al., 2001
;
Hausmann et al., 2003
).
Confirmation of a role for UV in the aggregation response of brush-turkey
chicks would constitute the first evidence for a new function, that of a cue
mediating social responses early in life.
It will be important to establish whether the perceptual preferences
described here are sufficiently specific to function as a species-isolation
mechanism. In Northern Queensland and New Guinea, brush-turkeys occur
sympatrically with the orange-footed megapode (Megapodius reinwardt).
The chicks of both species look alike to humans and they behave similarly and
live in the same habitat (Jones et al.,
1995). A comparative study will reveal whether specific movements
or morphological characteristics serve as species-recognition cues.
Our results will also allow exploration of the role of experience in the
development of species recognition in megapodes. If learning occurs, perhaps
triggered by specific cues that are inherently salient, then megapodes will
have properties convergent with those of cowbirds, in which such processes
play an important role (Hauber et al.,
2000,
2001
). If not, then megapodes
may represent a unique solution to the challenge of species recognition
without models.
![]() |
Acknowledgments |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Andersson, S. and Amundsen, T. (1997). Ultraviolet colour vision and ornamentation in bluethroats. Proc. R. Soc. Lond. B 263,843 -848.
Andersson, S., Örnborg, J. and Andersson, M. (1998). Ultraviolet sexual dimorphism and assortative mating in blue tits. Proc. R. Soc. Lond. B 265,445 -450.[CrossRef]
Bennett, A. T. D. and Cuthill, I. C. (1994). Ultraviolet vision in birds: what is its function? Vision Res. 34,1471 -1478.[CrossRef][Medline]
Bennett, A. T. D., Cuthill, I., Partridge, J. and Maier, E. J. (1996). Ultraviolet vision and mate choice in zebra finches. Nature 380,433 -435.[CrossRef]
Bennett, A. T. D., Cuthill, I. C., Partridge, J. C. and Lunau,
K. (1997). Ultraviolet plumage colors predict mate
preferences in starlings. Proc. Natl. Acad. Sci. USA
94,8618
-8621.
Boughman, J. W. (2002). How sensory drive can promote speciation. Trends Ecol. Evol. 17,571 -577.[CrossRef]
Bowmaker, J. K., Heath, L. A., Wilkie, S. E. and Hunt, D. M. (1997). Visual pigments and oil droplets from six classes of photoreceptors in the retinas of birds. Vision Res. 37,2183 -2194.[CrossRef][Medline]
Bradbury, J. W. and Vehrencamp, S. L. (1998). Principles of Animal Communication. Sunderland, MA: Sinauer Associates.
Bright, A. and Waas, J. R. (2002). Effects of bill pigmentation and UV reflectance during territory establishment in blackbirds. Anim. Behav. 64,207 -213.[CrossRef]
Cummings, M. E., Rosenthal, G. G. and Ryan, M. J. (2003). A private ultraviolet channel in visual communication. Proc. R. Soc. Lond. B 270,897 -904.[CrossRef][Medline]
Cuthill, I. C., Bennett, A. T. D., Partridge, J. C. and Maier, E. J. (1999). Plumage reflectance and the objective assessment of avian sexual dichromatism. Am. Nat. 153,183 -200.[CrossRef]
Cuthill, I. C., Partridge, J. C., Bennett, A. T. D., Church, S. C., Hart, N. S. and Hunt, S. (2000). Ultraviolet vision in birds. Adv. Study Behav. 29,159 -214.
Endler, J. A. (1990). On the measurements and classification of colour in studies of animal colour patterns. Biol. J. Linn. Soc. 41,315 -352.
Endler, J. A. (1992). Signals, signal conditions, and the direction of evolution. Am. Nat. 139,125 -153.[CrossRef]
Endler, J. A. (1993a). The colour of light in forests and its implications. Ecol. Monogr. 63, 1-27.
Endler, J. A. (1993b). Some general comments on the evolution and design of animal communication systems. Phil. Trans. R. Soc. Lond. Ser. B 340,215 -225.[Medline]
Endler, J. A. and Basolo, A. L. (1998). Sensory ecology, receiver biases and sexual selection. Trends Ecol. Evol. 13,415 -420.[CrossRef]
Fleishman, L. J. (1992). The influence of the sensory system and the environment on motor patterns in the visual display of anoline lizards and other vertebrates. Am. Nat. 139,S36 -S61.[CrossRef]
Galef, B. G. (1993). Functions of social learning about food; a causal analysis of effects of diet novelty on preference transmission. Anim. Behav. 46,257 -265.[CrossRef]
Göth, A. (2001a). Innate predator recognition in Australian Brush-turkey hatchlings. Behaviour 138,117 -136.[CrossRef]
Göth, A. (2001b). Survival, habitat selectivity and behavioural development of the Australian brush-turkey Alectura lathami. Ph.D. Thesis. Griffith University, Brisbane, Australia.
Göth, A. (2002). Behaviour of Australian brush-turkey (Alectura lathami, Galliformes: Megapodiidae) hatchlings following underground hatching. J. Ornithol. 143,477 -488.[CrossRef]
Göth, A. and Jones, D. N. (2003). Ontogeny of social behaviour in the megapode Alectura lathami (Australian brush-turkey). J. Comp. Psychol. 117, 36-43.[CrossRef][Medline]
Göth, A. and Proctor, H. (2002). Pecking preferences in hatchlings of the Australian brush-turkey: the role of food type and colour. Austr. J. Zool. 50, 93-102.[CrossRef]
Göth, A. and Vogel, U. (2002). Chick survival in the megapode Alectura lathami (Australian brush-turkey). Wildl. Res. 29,503 -511.[CrossRef]
Göth, A. and Vogel, U. (2003). Juvenile dispersal and habitat selectivity in the megapode Alectura lathami (Australian brush-turkey). Wildl. Res. 30, 69-74.[CrossRef]
Hamilton, W. J. and Orians, G. H. (1965). Evolution of brood parasitism in altricial species. Condor 67,389 -398.
Hart, N. S. (2001). The visual ecology of avian photoreceptors. Prog. Ret. Eye Res. 20,675 -703.[CrossRef][Medline]
Hasson, O. (1997). Towards a general theory of biological signalling. J. Theor. Biol. 185,139 -156.[CrossRef][Medline]
Hauber, M. E. (2002). First contact: a role for adult-offspring social association in the species recognition system of brood parasites. Ann. Zool. Fennici 39,291 -305.
Hauber, M. E. and Sherman, P. W. (2001). Self-referent phenotype matching: theoretical considerations and empirical evidence. Trends Neurosci. 24,609 -616.[CrossRef][Medline]
Hauber, M. E., Sherman, P. W. and Paprika, D. (2000). Self-referent phenotype matching in a brood parasite: the armpit effect in brown-headed cowbirds (Molothrus ater). Anim. Cog. 3,113 -117.[CrossRef]
Hauber, M. E., Russo, S. A. and Sherman, P. W. (2001). A password for species recognition in a brood-parasitic bird. Proc. R. Soc. Lond. B 268,1041 -1048.[CrossRef][Medline]
Hausmann, F., Arnold, K. E., Marshall, N. J. and Owens, I. P. F. (2003). Ultraviolet signals in birds are special. Proc. R. Soc. Lond. B 270, 61-67.[CrossRef][Medline]
Hess, E. H. (1958). "Imprinting" in animals. Sci. Am. 198,81 -90.
Hill, G. E. (1991). Plumage coloration is a sexually selected indicator of male quality. Nature 350,337 -339.[CrossRef]
Hunt, S., Cuthill, I. C., Swaddle, J. P. and Bennett, A. T. D. (1997). Ultraviolet vision and band-colour preferences in female zebra finches, Taeniopygia guttata. Anim. Behav. 54,1383 -1392.[CrossRef][Medline]
Hunt, D. M., Cuthill, I., Bennet, A. T. D. and Griffith, R. (1999). Preferences for ultraviolet partners in blue tit. Anim. Behav. 58,809 -815.[CrossRef][Medline]
Hunt, S., Cuthill, I. C., Bennett, A. T. D., Church, S. C. and Partridge, J. C. (2001). Is the ultraviolet waveband a special communication channel in avian mate choice? J. Exp. Biol. 204,2499 -2507.[Medline]
Husband, S. and Shimizu, T. (2001). Evolution of the avian visual system. In Avian Visual Cognition (On-Line) (ed. R. G. Cook). www.pigeon.psy.tufts.edu/avc/husband/.
Jacobs, G. H. (1993). The distribution and nature of colour vision among the mammals. Biol. Rev. 68,413 -471.[Medline]
Jones, D. N. (1988). Hatching success of the Australian brush-turkey Alectura lathami in South-East Queensland. Emu 88,260 -263.
Jones, D. N., Dekker, R. W. R. J. and Roselaar, C. S. (1995). The Megapodes. Oxford: Oxford University Press.
Keeling, L. J. and Hurnik, J. F. (1993). Chickens show socially facilitated feeding behaviour in response to a video image of a conspecific. Appl. Anim. Behav. Sci. 36,223 -231.[CrossRef]
Lorenz, K. (1937). The companion in the bird's world. Auk 54,245 -273.
Maier, E. J. (1994). UV vision in birds: a summary of latest results concerning the extended spectral range of birds. J. Ornithol. 135,179 -192.
Nakayama, K. and Loomis, J. M. (1974). Optical velocity patterns, velocity-sensitive neurons, and space perception: a hypothesis. Perception 3, 63-80.[Medline]
Odeen, A. and Hastad, O. (2003). Complex
distribution of avian color vision systems revealed by sequencing the SWS1
opsin from total DNA. Molec. Biol. Evol.
20,855
-861.
Osorio, D., Vorobyev, M. and Jones, C. D.
(1999). Colour vision of domestic chicks. J. Exp.
Biol. 202,2951
-2959.
Patricelli, G. L., Uy, J. A. C., Walsh, G. and Borgia, G. (2002). Male display adjusted to female's response. Nature 415,279 -280.[CrossRef][Medline]
Payne, R. B., Payne, L. L., Woods, J. L. and Sorenson, M. D. (2000). Imprinting and the origin of parasite-host species associations in brood-parasitic indigobirds, Vidua chalybeata.Anim. Behav. 59,69 -81.[CrossRef][Medline]
Peters, R. A., Clifford, C. W. G. and Evans, C. S. (2002). Measuring the structure of dynamic visual signals. Anim. Behav. 64,131 -146.[CrossRef]
Rosenthal, G. G., Evans, C. S. and Miller, W. L. (1996). Female preference for dynamic traits in the green swordtail, Xiphophorus helleri. Anim. Behav. 51,811 -820.[CrossRef]
Ryan, M. J. and Rand, A. S. (1993). Species recognition and sexual selection as a unitary problem in animal communication. Evolution 47,647 -657.
Seeley, T. (1989). The honey bee colony as a superorganism. Am. Sci. 77,546 -533.
Sherman, P. W., Reeve, H. K. and Pfennig, D. W. (1997). Recognition systems. In Behavioural Ecology, 4th edition (ed. J. R. Krebs and N. B. Davies), pp.69 -98. Malden, MA: Blackwell Science.
Shettleworth, S. J. (1998). Cognition, Evolution, and Behavior. Oxford, New York: Oxford University Press.
Siegel, S. and Castellan, N. J. (1988). Nonparametric Statistics for the Behavioral Sciences. New York: McGraw-Hill.
Simpson, M. J. A. (1968). The display of the Siamese fighting fish (Betta splendens.). Anim. Behav. Monogr. 1,1 -73.
Soler, M. and Soler, J. J. (1999). Innate versus learned recognition of conspecifics in great spotted cuckoos Clamator glandarius. Anim. Cogn. 2, 97-102.[CrossRef]
Spalding, D. A. (1873). Instinct, with original observations on young animals. Macmillan's Magazine 27,282 -293.
ten Cate, C. and Vos, D. R. (1999). Sexual imprinting and evolutionary processes in birds: a reassessment. Adv. Study Behav. 28,1 -31.
ten Cate, C., Vos, D. R. and Mann, N. (1993). Sexual imprinting and song learning: two of one kind? Neth. J. Zool. 43,34 -45.
Turner, E. R. A. (1965). Social feeding in birds. Behaviour 24,1 -45.
Weller, M. W. (1968). The breeding biology of the parasitic black-headed duck. Living Bird 7, 169-207.
West, M. J. and King, A. P. (1987). Settling nature and nurture into an ontogenetic niche. Dev. Psychobiol. 20,543 -552.
Wong, S. (1999). Development and behaviour of hatchlings of the Australian brush-turkey Alectura lathami. Ph.D. Thesis. Griffith University, Brisbane, Australia.
Related articles in JEB: