Abstract Allomaternal care (AMC) is provided to the offspring by individuals other than the genetic mother, including several seemingly altruistic behaviors such as babysitting, carrying, nursing, creching, or huddling for thermoregulation. To determine whether there is any allomaternal care among free-ranging domestic dogs, from March 2015 to May 2019 a total of eight dog groups consisting of 19 adult females (range 2–3 females per group) that were matrilineal relatives, i.e., maternal grandmothers, aunts, daughters, sisters were observed during pup-rearing period (1st to 13 weeks of pups’ life). During the first two weeks, lactating bitches were observed to spend the most time with their own pups and suckled for almost the entire observation period (30 min). Lactating mothers started to venture out of their dens for short foraging trips when the pups were 1 week old, but it was more frequent at 3 weeks of age. From the 3rd week of kin-related pups’ life the lactating mothers were observed to wean, with a parallel shift of nursing and regurgitation for the pups done by other kin-related females showing the evidence of allonursing. The occurrence of all types of nursing activities i.e., duration of contact, nursing, feeding by regurgitation, and protection of pups was higher among the mothers than among the allomothers. In the case of biological mothers, the frequency and duration of contact, nursing and feeding by regurgitation decreased as the puppies aged, meanwhile in the case of allomothers, the frequency and duration of contact, nursing and feeding by regurgitation increased until 6 weeks of age, before switching to a decreasing trend. Allonursing in free-ranging domestic dogs was more common among older bitches i.e., maternal grandmothers. We propose four possible reasons of allonursing in the case of free-ranging dogs- 1) having excess milk perhaps due to high pup mortality allonursing may evolve as low cost behavior in free-ranging dogs, 2) allonursing may provide substantial benefits to pups regarding growth, survival, and the transfer of immune compounds, 3) insufficiency of own mother’s milk may be one of the causes of allonursing, and 4) free-ranging domestic dogs nurse each other’s pups perhaps to promote a set of affiliating and permissive relationships among the group members. As the studied groups contained matrilineal related female dogs that helped each other with allonursing, this study strongly suggests the kin selection theory especially as allonursing is highly prevalent in other, closely related, gregarious wild canids (gray wolves, golden jackals).

中文翻译：

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幼崽饲养：母亲和异母在自由放养家犬中的作用

摘要 异母照料 (AMC) 由遗传母亲以外的个体提供给后代，包括几种看似无私的行为，例如照看婴儿、携带、护理、抱婴儿或挤在一起以调节体温。为确定自由放养的家犬是否存在异母照顾，从2015年3月至2019年5月，共有8只犬组，由19只成年雌性（每组2-3只雌性）组成，它们是母系亲属，即外祖母在幼崽饲养期间（幼崽生命的第 1 至 13 周）观察阿姨、女儿、姐妹。在前两周，观察到哺乳期母犬与自己的幼崽在一起的时间最多，并且几乎在整个观察期（30 分钟）都吃奶。哺乳期的母亲在幼崽 1 周大时开始冒险离开巢穴进行短途觅食旅行，但在 3 周大时更为频繁。从有亲缘关系的幼崽生命的第 3 周开始，观察到哺乳母亲断奶，同时由其他有亲缘关系的雌性对幼崽进行哺乳和反流，这显示了异母哺乳的证据。所有类型的护理活动，即接触时间、护理、反流喂养和保护幼崽的发生率在母亲中高于异母。在生母的情况下，接触、哺乳和反流喂养的频率和持续时间随着幼犬年龄的增长而减少，而在异母的情况下，接触、哺乳和反流喂养的频率和持续时间增加到6周龄, 在转向下降趋势之前。在自由放养的家犬中异养在年长的母犬中更为常见，即外祖母。我们提出了在自由放养的狗的情况下异养的四个可能原因 - 1) 有过多的牛奶可能是由于幼犬死亡率高 异养可能演变为自由放养狗的低成本行为，2) 异养可能为幼犬提供实质性的好处生长、存活和免疫化合物的转移，3) 自己母亲的母乳不足可能是异母喂养的原因之一，以及 4) 自由放养的家犬互相照顾彼此的幼崽，可能是为了促进一系列从属和宽容的关系小组成员。由于研究组包含母系相关的母犬，它们在异母喂养方面互相帮助，