Short Communications

The Wilson Journal of Ornithology 130(4):000–000, 2018

Interspecific feeding at a nest: Snowy-browed Flycatcher as a helper at the Rufous-bellied Niltava nest, Yunnan, Southwest China

Kang Luo,1,2,3 Yunbiao Hu,4 Zhiyun Lu,1,2 and Donglai Li5*

ABSTRACT—Interspecific feeding has been recorded for the brood parasitic species (Shy 1982, McNair and many bird species worldwide, especially in Europe, yet little Duyck 1991). Compared to intraspecific helping information is available on interspecific feeding in China. (Griesser et al 2017, Koenig 2017), information Here we report a first sighting of an interspecific feeding case between a Rufous-bellied Niltava (Niltava sundara) regarding the possible adaption mechanisms and and a Snowy-browed Flycatcher (Ficedula hyperythra) the evolutionary explanations of this behavior is observed in the Ailao Mountains in Yunnan Province. lacking. Whether interspecific helping is an According to the images and films captured by a camera adaptive behavior is debatable because these trap, a male Snowy-browed Flycatcher was found serving as observations are not easy to understand from an a helper at the nest of a Rufous-bellied Niltava on 17 June 2017. The helping behavior lasted for at least 2 d. The evolutionary perspective (Droz´ ˙dz˙ et al. 2004). Rufous-bellied Niltava parents showed no aggression when Several explanations have been raised for this the helper approached their nestlings. We cannot determine unusual behavior. For example, a heightened drive the causes of the reported interspecific feeding of the to care for young is generally advantageous, and nestlings because the prior history of any of adults involved feeding heterospecific young is possibly so rare is unclear. The Rufous-bellied Niltava nestlings’ begging that no evolutionary modification of this trait behavior might have stimulated the interspecific feeding by the male Snowy-browed Flycatcher. Received 21 July 2017. occurs (Heber 2013). Furthermore, although Accepted 2 September 2018. interspecific parental care provides little evolu- tionary benefit to the feeding bird, individuals Ailao Mountains, helper, interspecific feeding, Rufous- engaging in interspecific provisioning behavior bellied Niltava, Snowy-browed Flycatcher. could benefit by increasing their parental abilities (Riedman 1982, Shy 1982, Trombino 1999) if experience improves nesting success (Lehrman Additional adults (alloparents or helpers) play and Wortis 1967, DeStevens 1978). an important role in raising and feeding young in Although .1,400 bird species have been some species. This behavior has been observed recorded in China, little information about inter- among some fishes, mammals, and at least 2.4% of specific feeding cases is available (but see Jiang et (Skutch 1961, Skutch and Koenig 1990, Fiss al 2016 for the first interspecific feeding report in et al. 2016). In birds, intraspecific helpers are more China). To better understand the function of common than interspecific helpers (Kristˇ ´ın 2009). interspecific feeding, precise descriptions of the Reviews on interspecific feeding in birds show that conditions behind the donor–recipient interactions this behavior is rare, yet interspecific feeding has are vital (Kristˇ ´ın 2009). Here we report the first been recorded in .20 bird families in addition to case of interspecific feeding between a Snowy- browed Flycatcher (Ficedula hyperythra) and a 1 Key Laboratory of Tropical Forest Ecology, Xish- Rufous-bellied Niltava (Niltava sundarain)in uangbanna Tropical Botanical Garden, Chinese Academy southwest China, detected using a camera trap. of Sciences, Mengla, Xishuangbanna, Yunnan, China 2 Ailaoshan Station for Subtropical Forest Ecosystem Studies, Chinese Academy of Sciences, Jingdong, China Methods and results 3 University of Chinese Academy of Sciences, Beijing, China On 13 June 2017, a cup nest of Rufous-bellied 4 Institution of Zoology, Chinese Academy of Sciences, Niltava (built on a tree trunk with moss) was found Beijing, China 5 College of Life Sciences, Liaoning University, in the broadleaf evergreen forest near Ailaoshan 0 0 Shenyang, China Station (24832 N, 101801 E; 2,500 m a.s.l.). Four * Corresponding author: [email protected] nestlings about 1 week old were hosted in the nest. 1

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The nestlings fledged successfully on 22 June. interval. Of the 11 feeding cases by the male During 15–22 June 2017, we positioned a camera Snowy-browed Flycatcher, we were unable to trap (LTL Acorn 6210MC; Acorn Camera, Shenz- distinguish the provisioned food except for one hen City, China) to investigate the feeding caterpillar. behavior of Rufous-bellied Niltava. Camera set- The camera also captured the Snowy-browed ting: 1 JPG image þ 15 s video, trigger interval 1 Flycatcher removing fecal sacs on 2 occasions min between 1600 h on 15 June to 1700 h on 17 after feeding (Fig. 2). The following scene was June and 10 min trigger interval after that. Few more interesting: on one occasion, the Snowy- images and videos were captured after the early browed Flycatcher quickly left after feeding morning~0300hof19Junebecausean without waiting for the nestlings to defecate and unexpected fallen branch changed the angle of therefore without removing the fecal sacs. A the camera. nestling defecated about 10 s later, and the male According to the recorded videos and images, Rufous-bellied Niltava returned to the nest and we found that both sexes of the Rufous-bellied removed the fecal sacs immediately (Fig. 3). In Niltava reared the nestlings, with the main food addition, the male Snowy-browed Flycatcher being moths (Lithosiidae spp.). Unexpectedly, a displayed a strong alarm call when we rechecked male Snowy-browed Flycatcher arrived as a helper the nest in the afternoon of 18 June. to feed the nestlings of Rufous-bellied Niltava at 1108 h on 17 June (Fig. 1) and fed them 4 times that day. We counted the return times of the Discussion parents and the alloparent between 16 June and 18 June (during 0600 h to 2000 h). On 16 June the Heterospecific feedings are most common in parents returned 95 times while no alloparent heterospecific brood parasitism in cuckoos and showed up; on 17 June the parents returned 53 cowbirds. Several records have been published on times while the alloparent returned 4 times; on 18 interspecific feeding in different species, especially June the parents returned 8 times and the in the Oscines (Skutch 1961, Shy 1982, McNair alloparent returned 7 times (trigger interval was and Duyck 1991, Droz´ ˙dz˙ et al. 2004). In the changed to 10 min). More feeding trips by the present example, we cannot know with certainty male Snowy-browed Flycatcher were captured on the causes of the reported interspecific feeding of the second day. We believe the Snowy-browed the nestlings because we do not know the prior Flycatcher must have fed the nestlings more than history of any of adults involved (McNair and 11 times, although we did not record the feeding Duyck 1991). Shy (1982) and Eltzroth and because of the fallen branch and 10 min trigger Robinson (1984) state that misdirected parental

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Figure 1. The Rufous-bellied Niltava (Niltava sundara) nestlings fed by both parents and an alloparent: (a) female and (b) male Rufous-bellied Niltava feeding their nestlings moths; (c) first documented visit by alloparent, a male Snowy-browed Flycatcher (Ficedula hyperythra), to the nest; (d) male Snowy-browed Flycatcher feeding the Rufous-bellied Niltava nestlings.

care is the most likely the explanation when adult Rufous-bellied Niltava cup nests, 29 of which birds feed young of different species. Shy (1982) were on the ground in the bank, only one (our described 8 different categories that might stimu- study nest) was in a low tree trunk (A.B. Luo, late interspecific feeding. No Snowy-browed unpubl. data). The Rufous-bellied Niltava may Flycatcher nest was located near the Rufous- have acquired help from the male Snowy-browed bellied Niltava nest, and thus the Snowy-browed Flycatcher because the former gains some advan- Flycatchers were possibly drawn to interspecific tages for nesting in the flycatcher’s favorite nest food provisioning by the Rufous-bellied Niltava sites. nestlings’ begging behavior (Batisteli and Sarmen- To the best of our knowledge, this is the first to 2016). The Snowy-browed Flycatcher and report of interspecific feeding between a Snowy- Rufous-bellied Niltava nests have different shapes, browed Flycatcher and a Rufous-bellied Niltava. but the species share similarities in nesting habitat; Jiang et al. (2016) reported the first interspecific both build nest in holes in tree trunks, on stumps, feeding case in mainland China between the Olive- or on the ground along the banks (Clement 2017). backed Sunbird (Cinnyris jugularis)andthe In this study, we searched for nests throughout the Crested Bunting (Melophus lathami). With the 2017 breeding season (Mar–Aug) in a ~250,000 videos and images captured by the camera trap, we m2 area widely distributed in a 12 km2 forest near documented the details of interspecific feeding and Ailaoshan station. We recorded 9 Snowy-browed also observed the male Snowy-browed Flycatcher Flycatcher oval nests, all in tree trunks, and 30 remove fecal sacs. The removal of the sacs can

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Figure 2. The alloparent Snowy-browed Flycatcher would remove the fecal sacs after feeding the Rufous-bellied Niltava nestlings: (a) feeding the nestlings; (b) waiting for the nestling to defecate; (c) and (d) taking the fecal sac and flying away.

have strong implications for keeping the nest safe between the Wood Thrush (Hylocichla mustelina) from predation (Guigueno and Sealy 2012). and Eastern Towhee (Pipilo erythrophthalmus; Moreover, it is highly possible that the male Schaeffer et al. 2009). Lastly, only the male Snowy-browed Flycatcher fed the nestlings until Snowy-browed Flycatcher showed up as a helper, they left the nest because it also displayed strong which may support the hypothesis that males are alarm calls when we checked the nest on the more frequent helpers than females, perhaps afternoon of 18 June. These observations indicate because they have more time and opportunities that the helper Snowy-browed Flycatcher may not (Shy 1982, Cockburn 1998). just help in feeding the nestlings, but also in Note that the majority of the observations of keeping the nest clean, or even defending the such interspecific nest feeding precede modern territory of the ‘adopted’ nestlings. Furthermore, techniques such as nest videography, which has after the Snowy-browed Flycatcher fed the nest- revolutionized studies on avian parental care (Reif lings, the male Rufous-bellied Niltava removed and Tornberg 2006) by allowing the investigation fecal sacs promptly (Fig. 3) possibly indicating of events such as nest predation (Pietz and that the Rufous-bellied Niltava parents were aware Granfors 2000). We recommend that researchers of the existence of the helper or even spied on the heed interspecific helping when investigating helper when it was approaching and feeding their breeding in the field. Because the camera trap nestlings. The Rufous-bellied Niltava parents detected the interspecific feeding between the calmly accepted the services offered by the Snowy-browed Flycatcher and the Rufous-bellied Snowy-browed Flycatcher without showing ag- Niltava, we believe that more interspecific feeding gression, which differs from the case reported cases could be documented in China and else-

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Figure 3. The male Rufous-bellied Niltava removed fecal sacs after the alloparent fed the chicks but left without waiting for the nestlings to defecate: (a) Snowy-browed Flycatcher feeding the Rufous-bellied Niltava nestlings; (b) ~10 s after the alloparent left the nestlings started to defecate; (c) and (d) the male Rufous-bellied Niltava returned immediately and removed the fecal sacs.

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