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- Lind, Johan, et al.
(författare)
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Split-second escape decisions in blue tits (Parus caeruleus)
- 2002
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Ingår i: Die Naturwissenschaften. - : Springer Science and Business Media LLC. - 0028-1042 .- 1432-1904. ; 89:9, s. 420-423
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Tidskriftsartikel (refereegranskat)abstract
- Bird mortality is heavily affected by birds of prey. Under attack, take-off is crucial for survival and even minor mistakes in initial escape response can have devastating consequences. Birds may respond differently depending on the character of the predator's attack and these split-second decisions were studied using a model merlin (Falco columbarius) that attacked feeding blue tits (Parus caeruleus) from two different attack angles in two different speeds. When attacked from a low attack angle they took off more steeply than when attacked from a high angle. This is the first study to show that escape behaviour also depends on predator attack speed. The blue tits responded to a high-speed attack by dodging sideways more often than when attacked at a low speed. Escape speed was not significantly affected by the different treatments. Although they have only a split-second before escaping an attack, blue tits do adjust their escape strategy to the prevailing attack conditions.
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- Rydell, J, et al.
(författare)
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Evasive response to ultrasound by the crepuscular butterfly Manataria maculata
- 2003
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Ingår i: Naturwissenschaften. - : Springer Science and Business Media LLC. - 1432-1904 .- 0028-1042. ; 90:2, s. 80-83
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Tidskriftsartikel (refereegranskat)abstract
- The crepuscular nymphalid butterfly Manataria maculata was studied in Monteverde cloud forest, Costa Rica, during the dry season reproductive diapause. M. maculata has ears in the form of Vogel's organs located near the base of the forewings. Its behaviour in response to bursts of ultrasonic pulses (26 kHz, 110 dB SPL at 1 m) was condition-dependent. At dusk and dawn the sound consistently elicited evasive responses, similar to those of moths, in flying individuals. In contrast day-roosting individuals always remained motionless although they were alert to other stimuli. The daily movements between day- and night-roosts coincided in time and light intensity with the activity of insectivorous bats. This is the first reported case of ultrasonic hearing connected to evasive flights in a true butterfly (Papilionoidea). It strongly supports the idea that echolocating bats were involved in the evolution of hearing in butterflies.
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- Tobler, Michael, et al.
(författare)
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Specific floater home ranges and prospective behaviour in the European starling, Sturnus vulgaris
- 2004
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Ingår i: Naturwissenschaften. - : Springer Science and Business Media LLC. - 1432-1904 .- 0028-1042. ; 91:2, s. 85-89
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Tidskriftsartikel (refereegranskat)abstract
- In many bird species, floaters are present on the breeding grounds in one or more years before they breed. There is increasing evidence that they have specific home ranges in which they search for information about current and future breeding opportunities. We investigated the role of prospecting in a migratory European starling (Sturnus vulgaris) population. Radio-tracking showed that male starling floaters use specific home range areas during the breeding period. Nest-box observations demonstrated that non-parental nest intrusion is common in the starling and that it is significantly more frequent during the nestling than during the incubation period. In addition, small groups of nest boxes were more likely to be occupied by starlings if they had been put up during the preceding breeding season. The results suggest that floaters try to acquire information about local breeding communities. One specific type of information may be the location of potential breeding sites.
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- Wassgren, A.-B., et al.
(författare)
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Sex Pheromone of the Pine Sawfly Macrodiprion nemoralis (Hymenoptera : Diprionidae) : Identification of (2S,3R,7R,9S)-3,7,9-Trimethyl-2-tridecanol as the Precursor for the Active Pheromone Acetate
- 2000
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Ingår i: Die Naturwissenschaften. - : Springer Science and Business Media LLC. - 0028-1042 .- 1432-1904. ; 87:1, s. 24-29
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Tidskriftsartikel (refereegranskat)abstract
- The main component of the sex pheromone precursor in females of Macrodiprion nemoralis was identified as a threo-3,7,9-trimethyl-2-tridecanol isomer, approximately 800 pg per female, by gas chromatography-mass spectrometry. Comparison of mass spectrometric ion chromatograms showed that the natural compound in the female extract has the same retention time and mass spectrum as one of the two synthetic threo peaks. The acetate of the synthetic 16-isomer mixture caught a large number of males in the field, confirming the structure of the active pheromone. Comparison of gas chromatograms of the natural female extract with the eight synthetic threo stereoisomers showed that the pheromone is the (2S,3R,7R,9S)-stereoisomer of 3,7,9-trimethyl-2-tridecyl acetate.
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