Bull-headed Shrike (Lanius bucephalus)

2020 ◽  
Author(s):  
Reuven Yosef ◽  
ISWG International Shrike Working Group
Keyword(s):  
Lanius Bucephalus

Function of courtship feeding in the Bull-headed Shrike,Lanius bucephalus

1985 ◽  
Vol 3 (2) ◽  
pp. 113-121 ◽  
Author(s):  
Satoshi Yamagishi ◽  
Mitsuru Saito
Keyword(s):  
Courtship Feeding ◽  
Lanius Bucephalus

Seasonal change in egg-volume variation within a clutch in the Bull-headed Shrike, Lanius bucephalus

2003 ◽  
Vol 81 (2) ◽  
pp. 287-293 ◽  
Author(s):  
Masaoki Takagi
Keyword(s):  
Seasonal Change ◽  
Egg Volume ◽  
Hatching Order ◽  
Volume Variation ◽  
Significant Difference ◽  
Lanius Bucephalus ◽  
Clutch Initiation ◽  
The Mean ◽  
The Cost ◽  
Breeding Seasons

I studied the seasonal change in egg volume in Bull-headed Shrikes, Lanius bucephalus, to explore the importance of egg-volume variation within a clutch. The mean egg volume did not change over a season; however, the coefficient of variation in egg volume in six-egg clutches significantly increased in 1994 and 1995 but did not change in 1996. Peaks in arthropod biomass occurred early in the breeding seasons in 1994 and 1995, but late in the season in 1996. Higher food availability was related to a reduction in variation in egg volume within a clutch. A significant difference in egg volume was found within six-egg clutches, and the first egg was the smallest. Nestlings that hatched from small eggs early in the hatching order suffered lower mortality rates than nestlings that hatched from large eggs laid late in the hatching order. The duration of time between settlement of a female in a male territory and clutch initiation decreased with date. Intraclutch variation in egg volume may be caused by a trade-off between the time to develop an egg and the volume of the first egg within a clutch. Because eggs that hatch first do not need to be large for the hatchling to survive, the Bull-headed Shrikes may advance the clutch-initiation date at the cost of reducing the volume of the first egg.

scholarly journals Risk-taking behavior of bull-headed shrikes that recently colonized islands

2020 ◽  
Author(s):  
Shoji Hamao ◽  
Hisahiro Torikai ◽  
Midori Yoshikawa ◽  
Yutaka Yamamoto ◽  
Tugeru Ijichi
Keyword(s):  
Risk Taking ◽  
Natural Environment ◽  
Rattus Rattus ◽  
Predation Rate ◽  
Nest Site Selection ◽  
Predator Species ◽  
Black Rat ◽  
Lanius Bucephalus ◽  
Risk Taking Behavior ◽  
Selection Of

Abstract Individuals which have invaded urbanized environments are reported to engage in riskier behaviors, possibly influenced by the scarcity of predators in urbanized areas. Here, we studied the risk-taking behavior of birds which had invaded a new natural environment, rather than an artificial urban environment, using recently established populations of the bull-headed shrike Lanius bucephalus, which naturally colonized three subtropical islands in Japan. We compared flight initiation distance (FID), the distance at which an individual approached by a human initiates flight, between the islands and the temperate mainland. FID was longer for the insular shrikes compared with the mainland shrikes after controlling for other factors, indicating that the individuals which had invaded a new natural environment had a lower propensity for risk-taking. A possible explanation for these results is that low risk-taking behavior might be adaptive on the islands due to predation by the black rat Rattus rattus, an unfamiliar predator not found in shrike habitats on the temperate mainland. Further studies are needed to examine the nest predation rate, predator species, and nest site selection of these insular shrike populations.

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