Janssens E, Dauwe T, Van Duyse E, Beernaert J, Pinxten R, Eens M
Department of Biology, University of Antwerp (U.I.A.), Universiteitsplein 1, B-2610 Wilrijk, Belgium.
Arch Environ Contam Toxicol. 2003 Jul;45(1):121-7. doi: 10.1007/s00244-002-0133-7.
Several studies have shown that elevated levels of certain heavy metals may affect the behavior of birds and mammals. However, most of these studies were carried out under controlled laboratory conditions; results from free-living populations are scarce. In this study we examined the possible effects of exposure to high heavy metal concentrations on the aggressive behavior of resident great tit (Parus major) males by means of simulated territorial intrusion experiments during the egg-laying and incubation period at a highly polluted and a reference site. We also examined the effects of heavy metal exposure on the breeding performance of the tested couples, and we examined the plasma testosterone concentrations of great tit males in both study sites. We found no significant differences in the aggressive behavior between great tits at the polluted and the reference site during the egg-laying period. During the incubation period, responding male great tits at the polluted site performed significantly more aggressive flights around the decoy than did males at the reference site. During this period, there was also a tendency that more responding males were out of sight of the observer for some time during the experiment at the reference site than at the polluted site and this also for a longer period of time. Other behavioral parameters did not differ significantly between the two sites. Although plasma testosterone levels were higher at the polluted site, they did not differ significantly between the two sites. The tested couples at the polluted site interrupted their laying sequence significantly more and hatching success was significantly reduced compared to the tested birds at the reference site. We found no significant difference in clutch size, the length of the laying interruptions, fledging success, and fledgling age between the two sites. Although our results showed only minor alterations in the territorial aggressive behavior of male great tits exposed to heavy metal pollution, these small changes may have an important influence on the breeding and survival of these birds.
多项研究表明，某些重金属水平升高可能会影响鸟类和哺乳动物的行为。然而，这些研究大多是在受控的实验室条件下进行的；来自自由生活种群的研究结果很少。在本研究中，我们通过在一个高度污染的地点和一个对照地点的产卵和孵化期进行模拟领地入侵实验，研究了暴露于高重金属浓度对留鸟大山雀（Parus major）雄性攻击行为的可能影响。我们还研究了重金属暴露对受试配对繁殖性能的影响，并检测了两个研究地点大山雀雄性的血浆睾酮浓度。我们发现，在产卵期，污染地点和对照地点的大山雀在攻击行为上没有显著差异。在孵化期，污染地点对诱饵做出反应的雄性大山雀比对照地点的雄性大山雀围绕诱饵进行的攻击飞行显著更多。在此期间，对照地点在实验过程中有更多做出反应的雄性大山雀在一段时间内脱离观察者视线的趋势，而且这种脱离视线的时间也更长，相比之下，污染地点的情况则不同。两个地点的其他行为参数没有显著差异。虽然污染地点的血浆睾酮水平较高，但两个地点之间没有显著差异。与对照地点的受试鸟类相比，污染地点的受试配对显著更多地中断了它们的产卵顺序，孵化成功率也显著降低。我们发现两个地点在窝卵数、产卵中断时长、出飞成功率和雏鸟年龄方面没有显著差异。尽管我们的结果表明，暴露于重金属污染的雄性大山雀在领地攻击行为上只有微小变化，但这些小变化可能对这些鸟类的繁殖和生存产生重要影响。
