Data from: Neighborhood bully: no difference in territorial response towards neighbors or strangers in marmots

Territorial animals are expected to adjust their response to intruders
according to the perceived threat-level. One of the factors that drives
threat-level is the identity of the intruder. The dear enemy phenomenon
theory postulates that individuals should respond with lower intensity to
neighbors, already possessing a territory, than to strangers that may
fight to evict them. In social species, the hierarchical status of the
intruder might also mediate this response. Such behavioral adjustments
presuppose a capacity to discriminate between individuals posing different
threat levels. Here, we tested the behavioral response of Alpine marmots
to territorial intrusions in a wild population. We compared both dominant
females and males responses to scents from neighbor and stranger dominant
males (dear enemy phenomenon) and to dominant and subordinate stranger
males (social status-specific response). In addition, we tested for any
covariance between male scents and social status. We showed that female
and male dominant marmots do not adjust the intensity of their behavioral
responses to whether the intruder’s territory is bordering or not
(neighbors or strangers) or to the intruder’s social status, even though
dominant and subordinate males are thought to pose different threats and
social status is encoded in scents. Thus, we did not find support for the
dear enemy phenomenon and conclude instead that, in dominant Alpine
marmots, no intruder should enter a foreign territory. Research taking a
more holistic approach of the evolution and maintenance of territoriality
is required to understand the flexibility of responses to intruders in
group-living species.

具有领地性的动物会根据感知到的威胁等级，调整其对入侵者的应对行为。影响威胁等级的因素之一，便是入侵者的身份。亲爱的敌人现象（dear enemy phenomenon）理论假定，相较于可能为驱逐领地所有者而发起争斗的陌生入侵者，领地动物对已拥有领地的邻居入侵者的反应强度会更低。在社会性物种中，入侵者的社会等级地位同样会调节这类应对行为。这类行为调整，预设了动物具备区分不同威胁等级个体的能力。本研究针对野生种群中的阿尔卑斯旱獭（Alpine marmots），测试了其针对领地入侵的行为反应。我们分别比较了优势雌性与优势雄性旱獭，对邻居与陌生优势雄性气味的反应（用于验证亲爱的敌人现象），以及对陌生优势雄性与从属雄性气味的反应（用于检验社会等级特异性应对行为）。此外，我们还检验了雄性气味与社会等级间的协变关系。研究结果显示，无论入侵者的领地是否与自身领地接壤（即邻居或陌生入侵者），亦或是入侵者的社会等级地位如何，优势雌雄旱獭均未调整其行为反应强度——尽管学界普遍认为优势雄性与从属雄性会带来不同程度的威胁，且社会等级可通过气味进行编码。因此，本研究未发现支持亲爱的敌人现象的证据，反而得出结论：在优势阿尔卑斯旱獭种群中，任何入侵者均不应进入外来领地。未来需采用更整体化的研究范式，探索领地行为的演化与维持机制，方能理解群居物种对入侵者的反应灵活性。