Nest defenses and egg recognition of yellow-bellied prinia against cuckoo parasitism

Abstract

Parasites may, in multi-parasite systems, block the defenses of their hosts and thus thwart host recognition of parasites by frequency-dependent selection. Nest defenses as frontline may block or promote the subsequent stage of defenses such as egg recognition. We conducted comparative studies of the defensive strategies of a host of the Oriental cuckoo Cuculus optatus, the yellow-bellied prinia Prinia flaviventris, in mainland China with multiple species of cuckoos and in Taiwan with a single cuckoo species. Cuckoo hosts did not exhibit aggression toward cuckoos in the presence of multiple cuckoo species but showed strong aggressive defenses of hosts directed toward cuckoos in Taiwan. Furthermore, the cuckoo host in populations with a single cuckoo species was able to distinguish adults of its brood parasite, the Oriental cuckoo, from adult common cuckoos (Cuculus canorus). This represents the first case in which a cuckoo host has been shown to specifically distinguish Oriental cuckoo, from other Cuculus species. Hosts ejected eggs at a higher rate in a single cuckoo species system than in a multi-species cuckoo system, which supports the strategy facilitation hypothesis. Granularity analysis of variation in egg phenotype based on avian vision modeling supported the egg signature hypothesis in hosts because Taiwanese prinias increased consistency in the appearance of their eggs within individual hosts thus favoring efficient discrimination against cuckoo eggs. This study significantly improves our knowledge of intraspecific variation in antiparasitism behavior of hosts between single- and multi-cuckoo systems.

Multiple mechanisms of egg recognition in a cuckoo host

“…Here, the first host eggs seem to play a key role in such observational learning of each breeding attempt. A previous study also supported this assumption because the yellow-bellied prinia lays eggs with a low intra-clutch variation as a defense against cuckoo parasitism (Yang et al 2014b). Thus, the first egg is an important representation of the hosts' own egg phenotype.…”

“…1 m. It lays eggs with highly dense brown markings that cover almost the entire eggs ( Fig. 1), and it is parasitized by the Oriental cuckoo C. optatus with highly mimetic eggs (Yang et al 2014b). In this study, we used eggs from the common tailorbird O. sutorius as poorly mimetic eggs for parasitism experiments (see in the next sections).…”

Egg rejection and clutch phenotype variation in the plain priniaPrinia inornata

“…It is widely distributed in southern China (MacKinnon and Phillipps 1999), and breeds sympatrically with the yellow-bellied prinia in both study areas (Yang et al 2013(Yang et al , 2014b. It is widely distributed in southern China (MacKinnon and Phillipps 1999), and breeds sympatrically with the yellow-bellied prinia in both study areas (Yang et al 2013(Yang et al , 2014b.…”

“…We systematically searched for prinia nests and kept detailed records. Using uniform type and color of model eggs to test the different responses to foreign egg in a species are feasible and reliable (Underwood and Sealy 2006a, Yang et al 2014b, 2015. Active nests were randomly experimentally parasitized by adding a foreign egg into a clutch of the host species on the day after clutch completion or early during incubation (a floating test to estimate laying date, cf.…”

“…According to previous studies and the geographic history of Taiwan, bird species and populations on the island were suggested to be derived from the mainland (Chen et al 2000, Yeung et al 2011, Yang et al 2015. The oriental cuckoo uses the yellow-bellied prinia Prinia flaviventris, which exists in sympatry with the plain prinia, as its host (Zhang 1980, Yang et al 2013, 2014b. In contrast, on Taiwan only the oriental cuckoo Cuculus optatus was found in the locality of the current study.…”