Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA.
Department of Neurobiology, Physiology & Behavior, University of California, One Shields Ave., Davis, CA 95616, USA.
Horm Behav. 2019 Apr;110:10-18. doi: 10.1016/j.yhbeh.2019.02.001. Epub 2019 Feb 23.
In many passerine birds, testosterone stimulates song and aggression but inhibits paternal care, but few studies have explored whether such effects can be reversed with testosterone blockers. We explored the effect of testosterone blockers on song, aggression and paternal care of Lapland longspurs (Calcarius lapponicus), an arctic passerine with a short breeding season. Twenty-one "blocker males" received implants containing an androgen receptor blocker and an aromatase inhibitor, compared to 27 control males with empty or no implants. Song, aggression and other behaviors were evaluated with simulated territorial intrusions (STI) during mate-guarding, and with focal observations (without STI) during mate-guarding and incubation. Nests were monitored and nestlings weighed as an indirect measure of paternal care. During STI, blocker males exhibited similar song rates, significantly lower aggression, and were significantly less likely to be found on territory than control males. Focal observations revealed no differences in spontaneous song, aggression, foraging, preening, or flight activity. Blocker males' nestlings had greater body mass on day 5 after hatching, but this difference disappeared by fledging, and both groups fledged similar numbers of young. Two blocker males exhibited unusual paternal care: incubation and brooding of young, or feeding of nestlings at another male's nest. In sum, testosterone blockers affected aggression but not song, contrasting with results from previously published testosterone implant studies. Effects on paternal care were concordant with testosterone implant studies. These patterns may be related to rapid behavioral changes characteristic of the short breeding season of the Arctic.
在许多雀形目鸟类中，睾丸激素会刺激鸣唱和攻击行为，但会抑制亲代抚育行为，但很少有研究探讨是否可以用睾丸激素阻滞剂来逆转这些影响。我们探讨了睾丸激素阻滞剂对北极燕鸥（Calcarius lapponicus）的鸣唱、攻击和亲代抚育行为的影响，北极燕鸥是一种繁殖期短的北极雀形目鸟类。21 只“阻滞剂雄鸟”接受了含有雄激素受体阻滞剂和芳香酶抑制剂的植入物，与 27 只接受空植入物或未接受植入物的对照雄鸟进行了比较。在伴侣保卫期间，通过模拟领地入侵（STI）评估了鸣唱、攻击和其他行为，在伴侣保卫和孵化期间通过焦点观察（无 STI）评估了行为。监测巢并称重雏鸟，作为亲代抚育的间接衡量标准。在 STI 期间，阻滞剂雄鸟表现出相似的鸣唱率，攻击性明显降低，且在领地内被发现的可能性明显低于对照雄鸟。焦点观察显示，自发鸣唱、攻击、觅食、理羽和飞行活动没有差异。阻滞剂雄鸟的雏鸟在孵化后第 5 天体重更大，但这种差异在离巢时消失，两组都离巢了相似数量的幼鸟。有 2 只阻滞剂雄鸟表现出异常的亲代抚育行为：孵化和育雏，或在另一只雄鸟的巢中喂养雏鸟。总之，睾丸激素阻滞剂影响攻击行为而不影响鸣唱，这与之前发表的睾丸激素植入研究结果相反。对亲代抚育行为的影响与睾丸激素植入研究一致。这些模式可能与北极繁殖季节短暂的快速行为变化有关。
