Maisteriseminaari
Male dominance and female choice
on black grouse leks
Anni Hämäläinen
Jyväskylän yliopisto
Bio- ja ympäristötieteiden laitos
Ekologia ja ympäristönhoito
7.4.2006
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Contents:
TIIVISTELMÄ .................................................................................................................................................. 3
ABSTRACT ........................................................................................................................................................................ 4
1
INTRODUCTION.................................................................................................................................................... 5
2
THEORY FRAME................................................................................................................................................... 6
2.1
Dominance ................................................................................................................................................ 6
2.2
Female choice ........................................................................................................................................... 6
3
LEKS ......................................................................................................................................................................... 7
4
BLACK GROUSE SEXUAL SELECTION .......................................................................................................... 8
4.1
Lekking in black grouse .......................................................................................................................... 8
4.2
Establishment of male dominance .......................................................................................................... 8
4.3
Dominance rank related to mating success ........................................................................................... 9
4.4
Female choice ......................................................................................................................................... 10
REFERENCES ................................................................................................................................................................. 11
Attachment 1 ..................................................................................................................................................................... 13
RESEARCH PLAN ......................................................................................................................................... 13
1 Background ................................................................................................................... 13
2 Schedule and instruction ............................................................................................... 13
3 Methods ......................................................................................................................... 13
2/14
JYVÄSKYLÄN YLIOPISTO, Matemaattis-luonnontieteellinen tiedekunta
Bio- ja ympäristötieteiden laitos
Ekologia ja ympäristönhoito
HÄMÄLÄINEN, ANNI:
Maisteriseminaari:
Työn ohjaajat:
Huhtikuu 2006
Koiraan dominanssi ja naaraan parinvalinta teeren soitimella
14 s.
Prof. Rauno Alatalo, Dr. Heli Siitari
TIIVISTELMÄ
Yksilöiden pariutumismenestys määräytyy useissa lajeissa koiras-koiras –kilpailun ja/tai
naaraan parinvalinnan kautta tai näiden kahden mekanismin yhteisvaikutuksesta. Lajeissa joissa
koiraat eivät voi pakottaa naaraita paritteluun eivätkä tarjoa naaraalle hedelmöityksen ohella muita
hyötyjä, naaraan parinvalinta ratkaisee sen, millaiset koiraat pääsevät jatkamaan sukua. Tästä
johtuen koiraiden täytyy mainostaa kuntoisuuttaan ja pyrkiä dominanttiin asemaan houkuttaakseen
naaraita ja saadakseen paritteluja. Sosiaalinen dominanssi on usein yhteydessä koiraan
pariutumismenestykseen, mutta dominanssilla voi olla myös ”sivuvaikutuksia”, kuten sperman
vähyys tai suurempi altistuminen sukupuoliteitse leviäville taudeille. Naaraiden onkin tärkeää
tunnistaa erot luotettavien kuntoisuuden ilmentäjien ja pelkän dominanssin välillä löytääkseen
parhaan parittelukumppanin.
Soidin on hyvä esimerkki pariutumisjärjestelmästä, jossa dominanssi ja naaraan valinta
vaikuttavat yhdessä. Soitimet ovat koiraiden ryhmittymisalueita, joille naaraat tulevat ainoastaan
valitsemaan koiraita ja parittelemaan. Koiras ei tarjoa naaraalle hedelmöityksen lisäksi mitään
hyötyjä, joten naaraat panostavat parinvalintaan paljon. Teeri (Tetrao tetrix) on yksi tutkituimmista
ja parhaiten ymmärretyistä soidinlajeista. Teerikoirailla on useita sekundaarisia seksuaalisignaaleita
ja ne taistelevat aggressiivisesti puolustaessaan pariutumisreviirejä, joilla naaraat vierailevat
arvioimassa koiraita. Parittelu vaatii naaraan suostumuksen, ja yleensä vain muutama dominantti
teerikukko saa valtaosan paritteluista. Seminaarissa pohditaan naaraan parinvalinnan ja koiraan
dominanssin yhteyttä teerellä.
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UNIVERSITY OF JYVÄSKYLÄ, Faculty of Mathematics and Science
Department of Biological and Environmental Science
Ecology and Environmental Management
HÄMÄLÄINEN, ANNI:
Master’s seminar:
Instructors:
April 2006
Male dominance and female mate choice on black grouse leks
14 pages
Prof. Rauno Alatalo, Dr. Heli Siitari
ABSTRACT
The mating success of individuals of many species is determined mainly through male-male
competition, female mate choice or the combined effect of these two mechanisms. In species where
males cannot force females to mate, and where males provide little or no benefits other than sperm
to fertilize the offspring, female choice of mates becomes of substantial importance in determining
the quality and amount of males to sire offspring. Consequently males are under pressure to
advertise their goodness and execute dominance over other males in order to attract females and
gain matings. Social dominance is often related to male mating success, but dominance may also
have “side effects”, such as sperm depletion and susceptibility to sexually transmitted disease. It is
important that females distinguish between mere social dominance and reliable signals of fitness in
order to find the best partner possible.
Lekking is a prime example of how dominance and female mate choice act together in a mating
system. Leks are aggregations of males where females come only to assess males, choose a mate
and copulate. Males provide nothing to the female or the offspring besides insemination; hence
females allocate quite a long time to mate choice. Black grouse (Tetrao tetrix) is one of the lekking
species most studied and well understood. Males exhibit various secondary sexual signals and fight
aggressively to defend mating territories, where females visit and evaluate the males. Matings are
initiated by females and generally only a few dominant males receive most of the copulations. This
seminar essay will evaluate the connection of female mate choice and male dominance in black
grouse.
4/14
1
INTRODUCTION
The mating success of males in the vast majority of fauna is defined through male-male –
competition. On the other hand, in some, especially avian species, occurrence of matings is
regulated through mate choice executed by females. Females of most genera are known to be the
sex that invests more in the production and care of offspring, both in time and energy, and it is not
uncommon for the female to maintain the young by herself, often receiving little or no assistance
from the father. Consequently, the less paternal care or other benefits to the female are offered by
the male, the more the female is expected to invest in mate choice. It is of outmost importance
especially when their companion provides them with no other benefit besides the sperm to fertilize
the offspring (Höglund & Alatalo 1995).
Female choosiness logically leads to competition and direct strategies by males to impress the
females of their worth. Males attempt to win fights or otherwise intimidate other males in order to
gain social dominance in the group and ideally thus enhance their reproductive prospects. Lately,
though, a few studies concerning the connection between male dominance and female mate choice
have indicated that male dominance may not always honestly signal male quality (for a review, see
Qvarnström & Forsgren 1998). Female ability to distinguish between good males and fakers is
therefore of great importance. Researchers, too, have faced the dilemma of signal honesty in studies
of sexual selection.
In many lekking species, where males aggregate to breeding territories, dominance seems to be
a fairly honest indication of male fitness or fighting success. Males display to observing females
and fight other males to gain access to better territories or resources, or to attain a dominant
position. In black grouse (Tetrao tetrix) matings occur on leks, where status defines the territory
position and mating success of males. Territories are defended by males in a way that the central
areas of a lek are most popular and require plenty of fighting to hold (Hovi et al. 1994, Rintamäki et
al. 1995a). Males are colorful and display various secondary sexual traits, most of which appear to
correlate with male dominance and/or mating success (Alatalo et al., manuscript). Females tour the
territories and mate usually only once with their chosen male; males cannot force females to
copulate (Rintamäki et al. 1995b).
In this seminar essay I will concentrate on the features of male dominance related to female
mate choice, and consider lekking as a mating system atop this theory frame. Finally, black grouse
lekking will be evaluated as a mechanism of mate choice.
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2
2.1
THEORY FRAME
Dominance
Dominance, according to Qvarnström and Forsgren (1998), can be defined as success in
contests. Dominant individuals prevent lower ranked ones from accessing mates or resources and
dominance hierarchies are maintained by differences in body size, weaponry, aggressiveness and
fighting ability. Often fighting is reduced by signals of condition or fighting ability, or status
badges. Dominance is commonly thought to be closely linked with individual quality. It should thus
signal goodness of a male to females as well, making it a reasonable expectation that females
should primarily choose dominant males for mating partners. Indeed, a vast quantity of data do exist
where male mating and reproductive success have been clearly related to male dominance rank (see
e.g. Alatalo et al. 1991, Klinkova et al. 2005)
The above theory has, however, been challenged by some data from recent research suggesting
that the relationship between male dominance and female choice is not quite so straight-forward.
Dominance has been found to correlate in some species with lowered paternal care (collared
flycatcher: Qvarnström 1997, dark-eyed junco: Ketterson 1992), sperm depletion due to multiple
copulations (Harris et al. 2005, Pitnick & Markow 1994), worse offspring quality (jackdaw:
Verhulst & Salomon 2004), male aggression toward the female (northern elephant seal: Le Boeuf &
Mesnick 1990) and increased disease and parasite transmission (mice: Freeland 1981, birds:
Sheldon 1993). These controversies have been explained as differences in motivation: an individual
dominant in contests over food or resting sites may not necessarily be triumphant in fights over
mates, depending on their priorities. Previous site knowledge or time of ownership may also
increase the value of a resource to an individual, adding determination to their resource defense
(Qvarnström & Forsgren 1998).
2.2
Female choice
When choosing mates, females must consider the possible imbalance between the costs and
gains of the socially highest ranking males. They may pick the dominant males to gain dominance
genes to pass to their offspring, or choose for other benefits or reduction of the possible costs
described above. Direct advantages of accurate mate choice to females may include good quality
sperm, predator avoidance and avoidance of disease or parasites. Ideally also the offspring quality
will be enhanced and more offspring produced. In black grouse the most popular cocks have also
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been found to live longer, providing a safe partner for the female for years to come (Alatalo et al.
1991, Rintamäki et al. 1997). When secondary sexual characteristics function as honest indicators
of the male’s condition and genetic goodness, female choice can enhance her offspring’s quality.
Møller & Alatalo (1999) found that male secondary sexual characteristics do indeed explain on
average 1,5 % of variation in offspring quality. Although it is a small percentage, it may well
influence female choice and population fitness in the evolutionary scale.
Mate choice may also have its complications. For instance, Reynolds & Gross (1990) have
argued that although choosiness over mates is expected to yield benefits by increasing the chances
of pairing with a desirable partner, it may also carry costs in terms of time, energy, and increased
risk of predation. Individuals may differ in their mate preferences according to their own age,
experience, size or genotype, so that if there is costly competition for mates, the poorest competitors
might be better off avoiding the highest-quality partners and instead targeting low-quality partners,
so that they minimize the costs they incur (Fawcett & Johnstone 2003).
3
LEKS
Lekking is a mating system in which males aggregate in groups to compete over females, while
the latter observe the males and choose their mates. By definition, a lek, according to Höglund &
Alatalo (1995), is a system in which males assemble into territorial groups during lekking season
and matings occur on the lek. No paternal care is provided by the male, and the territories generally
offer females no benefits in the form of shelter, nesting site or food. The only benefit females gain,
then, would be the male’s genes for their offspring (Bradbury 1981). Hence mate selection by
females can be expected to be of enormous importance and honest signals of male quality desirable.
Leks occur in many taxonomic groups (see Höglund & Alatalo 1995 for a review) but for
clarity, only birds will be covered in this seminar. In Finnish avian species, lekking is common in
capercaillie, black grouse, ruff and great snipe (Rintamäki et al. 1997). Group leks are thought to
have evolved due to reasons of predator avoidance, patchiness of appropriate mating places,
settlement on sites where habitats of many females meet (Höglund & Alatalo 1995), better
possibilities for females to compare males (Rintamäki et al. 1997) or due to temporal or spatial
spillover (Rintamäki et al.1995a).
Temporal spillover hypothesis suggests that females copulate on historically successful sites and
so lek sites persist over the years, while male territories persist as long as males survive. Spatial
spillover hypothesis, on the other hand, implies that as females prefer certain males, neighboring
males also receive a few matings by theft, female-female –aggression or female mistake, making it
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useful for weaker males to seek proximity of “hotshots” or attractive males. This also leads to
centrality observed in some leks, e.g. those of black grouse, where central males are the most
successful (Rintamäki et al.1995a). The most important requirement for the sustainability of leks is,
however, female choice. Females must seek out leks and deliberately come observe and mate with
males at the lekking site, while temporal and spatial spillovers perhaps amplify the size and stability
of the lek.
4
4.1
BLACK GROUSE SEXUAL SELECTION
Lekking in black grouse
The species selected for this thesis work is black grouse (Tetrao tetrix). It is a species in which
lekking is the sole reproductive strategy, while leks usually constitute between 1 and 15 displaying
males. Leks take place on bogs, fields, lake surfaces or other open grounds, and the position of a lek
is usually quite stable throughout years, although on lakes the entire lek may move even during the
season. Matings occur over a short period of time at the change of April and May, most activity
taking place in the early hours of mornings, and before sunset. Females arrive alone or in groups
after males and spend about an hour on a few mornings watching males, possibly evaluating them
already at distance. Females tour male territories, choose a male, copulate and lay eggs after a
couple of days. Males cannot force females to copulate, making the matings entirely dependent on
female choice (Rintamäki et al. 1995b)
Black grouse males allocate a lot of time in a timescale of several years to rise up in the
dominance rank and take over more central territories. Males often display at the lek arenas also in
the fall season in order to establish their territories for the following spring. Recent findings suggest
that this happens for the males to establish their territories already in the fall and maintain their
position through constant activity. It may also be of some mate choice significance since females
can use the opportunity to evaluate males already in the fall (Rintamäki et al. 1999).
4.2
Establishment of male dominance
Various physical and behavioral components define black grouse males’ mating success. Such
characteristics have lately been studied in detail by Alatalo et al. (manuscript), and include male
size, eye comb size and redness, blueness of feathers, lek attendance, vocal and fighting activity,
territory centrality and size, among others. They found territorial (attendance, centrality and
territory size) and display cues (fighting activity, tail posture and vocal activity) to be more variable
than morphological traits. Of all the variables tested, centrality, lek attendance and dominance as a
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yearling seem to be the best variables to explain male mating success. In a previous study it was
found that testosterone levels of males also strongly correlate with mating success, so that high
testosterone level predicts stronger secondary sexual signals, a more central territory and more
matings (Alatalo et al. 1996).
Of morphological traits, lyre length appears not to be significant per se – young males, however,
have shorter lyre, which may allow females to recognize age differences between males. Lyre
condition is related to male condition and hence to amount of matings. (Rintamäki et al.1997). The
effect is of more significance to young males but affects central males little, which implies that it is
a secondary cue mainly used when more reliable quality indicators are lacking (Höglund et al.
1994). The significance of rookooing activity (vocal activity) has been disputed: possible
suggestions are that it announces male presence reducing fights or attracts other individuals (male
and female) to the lek. Contradicting results on the connection of rookooing activity to mating
success exist (Rintamäki et al.1997, Koivisto 1965).
4.3
Dominance rank related to mating success
In black grouse leks, only a few males are successful in pairing: usually half of all the males
manage to mate, while only a few of them score the vast majority of the matings (Rintamäki et al.
1997, Alatalo et al. 1992, Krujit & de Vos 1988). Male fighting ability indicated by intact
ornaments and dominance relations predicts male viability, hence announcing good genes for
female selection (Alatalo et al. 1991). Alatalo et al. (1991) describe that males dominant in fall leks
and males winning fights over female dummies were most successful in mating. Attractive males
also had undamaged tails with none or very few feathers torn off their tale ornament in fights.
Successful males were twice more likely to survive the next 6 months, which implies their greater
viability, possibly making it relevant to female choice for good genes. The most preferred male on
each lek spent more time fighting than other males, and the preferred males were able to keep other
males further away in the presence of females than those that were unsuccessful. They constructed
an experiment in which a female grouse dummy was placed at a territory boundary of two males,
which is the location of most naturally occurring fights. Fights over the dummy were usually won
by the male more attractive to females also in actual matings. When inside a territory, however, the
territory holder managed to defend the dummy regardless of his dominance status.
Higher fighting activity predicts an increase in the number of matings. Whether this is a cause
or a result of the more central positions of the best males is unclear. Alternative explanations
offered include the following: best cocks are surrounded by worse individuals in hopes of chance
copulations; central position requires good fighting ability, and only the best cocks can hold this
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position; females favor tight groups of males, searching for the best cocks (which happen to be in
the middle) or the central cocks (which happen to be the best) (Rintamäki et al.1997, Alatalo et al.
1991, Hovi et al. 1994).
It has not been studied in black grouse whether male dominance gradient correlates with female
or hatchling survival or condition, in response to disease, parasites or sperm quality. Clutch size or
likelihood of fertilization are likely to be irrelevant for the black grouse, as sperm seems to be
enough for all fertilizations even among the most dominant males (Alatalo et al.1996). In case there
is variation in the other traits, it is likely to be small (personal consultation with Heli Siitari and
Rauno Alatalo).
4.4
Female choice
The direct advantages of successful mate choice to females can be expected to include good
quality sperm, predator avoidance and disease or parasite avoidance. These, in turn, would enhance
offspring quality and produce more fertile offspring, induce the female to lay a larger number of
eggs, and, if the cock also lives longer, it will make a safe partner for the female for the years to
come (Rintamäki et al. 1997, Alatalo et al. 1991).
Black grouse exhibit strictly speaking no couple bond, but if the male a female mated with
the previous year is alive, then the female chooses the same male again next year (Rintamäki et al.
1995a, Rintamäki et al. 1997). If not, she mates with the top cock or a male occupying the territory
previously occupied by her previous mate (Rintamäki et al. 1995b). Fidelity may count towards
direct benefits: it may be of importance for the female to become fertilized at the right time or be
allowed to mate without disturbance. Females do not seem to actively seek undisturbed copulations
as they prefer larger leks where disturbance is more common. Larger leks do, indeed, have a higher
total number of matings as well as higher number of copulations per male (Alatalo et al. 1992,
Rintamäki et al. 1997).
Females may also copy other females’ mate choices, amplifying the success rate of the best
males. Copying can be especially useful for young females who have usually recently immigrated
into the area and do not know the males or have arrived later, which creates a time constraint for
observation of males. The top male and old females have been shown to mate earlier than other
males and young females, which gives newcomers a chance to observe others’ choices. Choosing
the top male may be difficult and hence costly for females, making copying an efficient strategy
(Höglund et al. 1990).
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REFERENCES
Alatalo, R.V., Burke, T., Dann, J., Hanotte, O., Höglund, J., Lundberg, A., Moss, R., Rintamäki,
P.T. 1996: Paternity, disturbance and female choice in lekking black grouse. – Anim. Behav.
52: 861-873
Alatalo, R.V., Höglund, J., Lundberg, A. 1991: Lekking in the black grouse – a test of male
viability. – Nature 353
Alatalo, R.V., Höglund, J., Sutherland, W.J. 1992: Evolution of black grouse leks: female
preferences benefit males in larger leks. – Behav. Ecol. 3: 53-59
Bradbury, J.W. 1981: The evolution of leks. In R.D. Alexander & D.W. Tinkle, eds.: Natural
selection and social behaviour. pp 138-169. New York and Concord: Chiron Press
Fawcett, T.W. & Johnstone, R.A. 2003: Mate choice in the face of costly competition. – Behav.
Ecol. 14: 771–779
Freeland, W.J. 1981: Parasitism and behavioural dominance among male mice. – Science 213: 461462
Harris, W.E. & Moore, P.J. 2005: Female Mate Preference and Sexual Conflict: Females Prefer
Males That Have Had Fewer Consorts. – Am. Nat. 165
Hovi, M., Alatalo, R.V., Höglund, J., Lundberg, A., Rintamäki, P.T. 1994: Lek center attracts black
grouse females. – Proc. R. Soc. London Ser. B 258: 303-305
Höglund, J., Alatalo, R.V., Lundberg, A. 1990: Copying the mate choice of others? Observations on
female black grouse. – Behaviour 114: 1-4
Höglund, J., Alatalo, R.V., Lundberg, A., Rätti, O. 1994: Context-dependent effects of tailornament damage on mating success in black grouse. – Behav. Ecol. 5: 182-187
Höglund & Alatalo 1995: Leks. Princeton: Princeton University Press
Ketterson, E.D. et al. 1992: Testosterone and avian life histories: effects of experimentally elevated
testosterone on behavior and correlates of fitness in the dark-eyed junco (Junco hyemalis). –
Am. Nat. 140: 980-999
Klinkova, E.J. Hodges, K., Fuhrmann, K., de Jong, T., Heistermann, M. 2005: Male Dominance
Rank, Female Mate Choice and Male Mating and Reproductive Success in Captive
Chimpanzees. - International Journal of Primatology 26, No. 2
Koivisto, I. 1965: Behaviour of the black grouse, Lyrurus tetrix (L.), during spring display. –
Finnish Game Res, 26: 5-60
Kruijt, J.P. & de Vos, G.J. 1988: Individual variation in reproductive success in male black grouse,
Tetrao tetrix L. In T.H. Clutton-Brock, ed.: Reproductive success. Studies of individual
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variation in contrasting breeding systems. pp. 279-290. Chicago: University of Chicago
Press.
Le Boeuf, B.J. & Mesnick, S. 1990: Sexual behaviour of male northern elephant seals: I. Lethal
injuries to adult females. – Behaviour 116: 143-162
Møller, A.P. & Alatalo, R.V. 1999: Good-genes effects in sexual selection. – Proc. R. Soc. LOnd B
266:85-91
Pitnick, S. & Markow, T.A. 1994: Male gametic strategies: sperm size, testis size, and the allocation
of the ejaculate among successive mates by the sperm-limited fly Drosophila pachea and its
relatives. – Am Nat. 143: 785-819
Qvarnström, A. 1997: Experimentally increased batch size increases male competition and reduces
male paternal care in the collared flycatcher. – Proc. R. Soc. London Ser. B 264: 1225-1231
Qvarnström, A., & Forsgren, E. 1998: Should females prefer dominant males? Trend. Ecol. Evol.,
13: 498-501
Reynolds JD, Gross MR, 1990. Costs and benefits of female mate choice: is there a lek paradox?
Am Nat 136:230–243
Rintamäki, P.T., Alatalo, R.V., Höglund, J., Lundberg, A. 1995a: Male territoriality and female
choice on black grouse leks. – Anim. Behav. 49: 759-767
Rintamäki P.T., Alatalo, R.V., Höglund, J., Lundberg, A. 1995b: Mate sampling behavior in black
grouse females. – Behav. Ecol. Sociobiol. 37:209-215
Rintamäki, P.T., Hovi, M., Alatalo, R.V. 1997: Miten seksuaalivalinta toimii teeren soitimella. –
Suomen Riista 43: 48-55
Rintamäki, P.T., Karvonen, E., Alatalo, R.V., Lundberg, A. 1999: Why do black grouse perform on
lek sites outside the breeding season? – Journal of Avian Biology 30:359-366
Sheldon, B.C. 1993: Sexually transmitted disease in birds: occurrence and evolutionary
significance. – Philos. Trans. R. Soc. London Ser. B 339: 491-497
Verhulst, S. & Salomons, H.M. 2004. Why fight? Socially dominant jackdaws, Corvus monedula,
have low fitness. Anim. Behav. 68: 777-783
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Attachment 1
RESEARCH PLAN
1 Background
Black grouse mating system is much studied, and it has been established that a few dominant
males gain most of the copulations on each lekking site. Dominance is gained over a long period of
time through consistent effort by the male. So far male grouse dominance scale has been assessed
mainly through feeding experiments with yearling males and by assessing fights over taxidermic
female grouse dummies at the territory border of two males (Alatalo et al. 1991). Territory
centrality has also been used as indication of dominance rank. For the purpose of simplifying
dominance-related research, a consistent method for assessing dominance through behavior is
needed, since such behavioral assessment methods are still largely lacking. In order to address this
problem, behavioral components of lekking males will be observed in detail in my thesis research.
2 Schedule and instruction
The research will be conducted as observation of fights between males at nine lek sites in
central Finland during the spring lek of 2006 during the last weeks of April through to the
beginning of May. Video material from years 2001-2004 will be included as background material
and for the planning of videotaping, and parts where fights can be seen well will be used also for
analysis.
The instructors for the thesis work are Rauno Alatalo and Heli Siitari of the avian research
group at the Department of Biological and Environmental Science at the University of Jyväskylä.
The group is part of the Centre of Excellence Evolutionary Ecology research unit and my thesis
research project is in connection with other black grouse research conducted by researchers of the
group.
3 Methods
The observations will be implemented as part of the research group’s yearly lek watch. In
practice, each of the nine leks will have a person observing, videotaping and narrating the lekking
and individual behavior of the attendants. Preceding the lekking season, video from leks of previous
years is to be scanned in order to formulate hypotheses as to which components of fighting ability
are most likely to be significant. They are used also to plan the videotaping and narrating procedure
13/14
for spring 2006. Observing the individual behavior of the grouse is enabled as most of the males
and many females are individually marked with distinctive series of colored leg bands, in addition
to which some females carry radio transmitters. The winner of fights and the mating success of each
male will be recorded.
Tentatively, specific attention will be paid to two male behavior features during fights: the
“turning behavior” and the number of males fought with. Turning behavior is as follows: as the
fight draws to an end, one of the males will turn its tail to its opponent. This male is likely to be
dominant, as he need not worry about the other male attacking him across the territory border. If,
however, the more subordinate male comes to turn around first, the dominant one may cross the
border and tear feathers off the opponent’s tail. A damaged tail has been recorded to lower the
mating success of males (Höglund et al. 1994). The number of males fought with, on the other
hand, should demonstrate the overall control a male has over his territory.
The video material of spring 2006 will later be searched for individual fights between two
males, the fights observed in detail, and the features of the fight and strategies of each male
recorded. Of these, any behavior suggesting dominance will be extracted, and dominance statuses
assigned to each male. Finally, the mating success of each male is compared with their fighting
style.
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