Search results for "Grouse"

Black Grouse leks on ice: Female mate sampling by incitation of male competition?

1995

Male-male competition is assumed to limit female choice of mates, but it may also help females to choose the most vigorous males. We studied the mate sampling behaviour of female black grouse (Tetrao tetrix) at spatially unstable leks on ice-covered lakes. In the absence of territories and site-dependence in outcomes of fights, the male dominance hierarchy is very evident on ice. When being courted by dominant males, females frequently tried to approach other males. This was frequently prevented because (1) the courting male and the approached male were involved in physical fight, or (2) the dominant male followed the female and the approached male escaped and avoided contact with him. Thes…

Individual and Environmental Determinants of Daily Black Grouse Nest Survival Rates at Variable Predator Densities

2010

Nest predation in ground nesting black grouse (Tetrao tetrix) inhabiting managed boreal forests is arguably the single most important cause of nesting failure. Little is known, however, about indirect effects of other factors, such as maternal or environmental properties, and to what extent maternal and habitat qualities interact with varying levels of predator densities. Using an information-theoretical approach, we studied maternal and environmental determinants of daily nest survival rates under variable predator densities of 210 individual black grouse hens in central Finland. Environmental determinants were far more important than maternal ones, and the effects were more apparent at hi…

Paternity, copulation disturbance and female choice in lekking black grouse

1996

Female copulation behaviour in the black grouse, Tetrao tetrix, was studied by detailed observations of individually marked birds together with DNA fingerprinting analyses for paternity assessment. For each breeding occasion females typically mated only once with one male, and did not mate outside the lek arena. They re-mated with the same or another male usually only if the initial copulation was disturbed and was probably unsuccessful in sperm transfer. The willingness of females to copulate only once with one male suggests that multiple mating with several males incurs a cost that more than outweighs any possible fertility or sperm competition benefits. Attempts by neighbouring males to …

Low levels of relatedness on black grouse leks despite male philopatry

2008

In lekking species, males cluster on specific areas for display (the leks) and females generally prefer to copulate with males on large aggregations. The maintenance of leks in which only a few males reproduce might be explained if subordinate males gain indirect fitness benefits. By joining a lek on which relatives are displaying, subordinates might attract more females to the lek thereby increasing the mating opportunities of their kin. In black grouse, a genetic structure among leks has previously been found suggesting that relatives could display together. Using 11 microsatellite loci, we extended this result by testing for the presence of kin structures in nine black grouse leks (101 m…

Testosterone and male mating success on the black grouse leks

1996

On black grouse (Tetrao tetrix) leks females prefer dominant, viable males that have managed to acquire relatively central territories. The immunocompetence hypothesis predicts that, because high levels of testosterone are costly to the immune system, male sexual traits that are controlled by testosterone are likely to serve as reliable indicators of male health. Indeed, testosterone concentrations of black grouse males were highly variable, and strongly correlated with male mating success. This is related to the fact that males with high testosterone levels had most central territories. However, the association of testostestorone level with male mating success was not solely related to cen…

Short- and long-term population dynamical consequences of asymmetric climate change in black grouse

2006

Temporal asymmetry in patterns of regional climate change may jeopardize the match between the proximate and ultimate cues of the timing of breeding. The consequences on short- and long-term population dynamics and trends as well as the underlying mechanisms are, however, often unknown. Using long-term data from Finland, we demonstrate that black grouse ( Tetrao tetrix ) have responded to spring warming by advancing both egg-laying and hatching. However, early summer (the time of hatching) has not advanced, and chicks have to face colder post-hatching conditions. Demonstrating that these conditions are critical to post-hatching survival, we show that chicks are increasingly suffering highe…

Short communication: Landscape and season effects on the diet of the Goshawk

2009

There are two general effects of habitat loss and frag-mentation of mature boreal forests (Schmiegelow &Monkkonen 2002). First, fragmentation by farmlandcreates stable structures such as permanent edge zoneswith enrichment of species diversity and density(Andren 1992, Berg & Part 1994). Secondly, modernforestry with clear-cuts creates sharp, unstable bound-aries between forest and open areas, usually with lesspronounced edge effects (Helle 1983, Schmiegelow &Monkkonen 2002). Considering the vast array of stud-ies on the effects of habitat loss and fragmentation onbird populations, relatively little attention has beenpaid to the role of predators, other than nest preda-tors, across different…

Evolution of black grouse leks: female preferences benefit males in larger leks

1992

Mate sampling behaviour of black grouse females (Tetrao tetrix)

1995

We studied female mate sampling behaviour in lekking black grouse (Tetrao tetrix). Females mainly visited males occupying territories in the centre of the lek with relatively large territories. They were also more likely to visit males that had high attendance. The same factors were also correlated with male mating success. A multiple regression model including these factors explained more of the variance in female visits per male (53%) than in mating success (33%). The pattern of female sampling conformed with a pool comparison (best-of-n) tactic. Such a tactic is expected if the costs of sampling are low. Females of high body mass visited more males than lighter females, however, which in…

Lek centre attracts black grouse females

1994

In several lek mating systems, centrally located males enjoy higher mating success than peripheral males. The mechanism behind this pattern, however, has been controversial and a rigorous test of the different alternatives is missing. Here we report that in black grouse Tetrao tetrix , a lekking bird species, central males achieved many more copulations than males in the periphery. Generally, central territories were smaller than peripheral ones, and males were thus more clumped in the centre. A choice experiment in an aviary provided experimental support for females being attracted to densely clustered males, so that males in larger clusters have higher expected average mating success. Thu…