Data from: A tiny cuckoo: risk-dependent interspecific brood parasitism in a predatory mite

Many animal species protect their eggs against predators while others do not. When these species share the same habitat, the latter species may profit by adding their eggs to those of the protecting species. We show that one tiny predatory mite species protects its own eggs only to a limited extent, and instead adds them to those of another predatory mite species that does guard its eggs, resulting in reduced egg predation. This cuckoo behaviour comes with a cost, and therefore only occurs when egg predators are present. Furthermore, the parasites only add eggs to those of the guarding host species, not to those of another mite species that does not guard its eggs. To the best of our knowledge, this is the first study to show that facultative brood parasitism is more effective than brood care, in increasing offspring survival in the presence of egg predators.诸多动物物种会对自身卵粒采取防御捕食者的保护行为，另有部分物种则无此行为。当上述两类物种共享同一栖息地时，无保护行为的物种可通过将自身卵粒混入拥有卵保护行为的物种的卵团中获利。本研究发现，一种小型捕食螨（predatory mite）仅会在有限程度上保护自身卵粒，反而会将卵粒混入另一种会守护卵粒的捕食螨的卵团中，此举可降低自身卵粒遭遇捕食的概率。这种类似杜鹃的育幼寄生行为需付出相应代价，因此仅在存在卵捕食者的场景下才会发生。此外，该寄生螨仅会将卵粒混入具有卵守护行为的宿主物种的卵团中，而非不会守护卵粒的其他螨类物种的卵团。据我们所知，本研究首次证实：在存在卵捕食者的场景下，兼性育幼寄生（facultative brood parasitism）相较传统育幼照料更能提升子代存活率。