Mulleripicus funebris, (Valenciennes 1826) (Valenciennes, 1826)

Gicaraya, Vince Angelo G. & Española, Carmela P., 2024, First description of the breeding biology and behaviour of the near threatened northern sooty woodpecker Mulleripicus funebris (Valenciennes 1826) (Piciformes: Picidae) in Luzon Island, Philippines, Natural History Sciences 11 (1), pp. 15-20 : 16-17

RESULTS

Nest Tree and Cavity

A pair of northern sooty woodpecker was found taking turns excavating a cavity in the trunk of a Kupang Parkia timoriana (DC.) Merr. snag on 23 February 2022. The nest tree was situated at a forest edge surrounded by several large-girthed trees (≈ 2.5-4.0 m) and was approximately 5 m from a road. The nest tree has a girth at breast height of 181 cm. The cavity was excavated 16.4 m from the ground with a girth at nest height of 109 cm. The cavity entrance ( Fig. 1a ) had opening dimensions (L x W) of 9.0 x 8.0 cm; horizontal depth (measured from the opening rim to the wall of the cavity) of 18 cm; vertical depth (measured from the ceiling to the cavity floor) of 44 cm; and depth (measured from the opening rim to the cavity floor) of 37 cm. Aside from fine wood chips and several down feathers, no other materials were found lining the nest ( Fig. 1b ).

BEHAVIOURAL OBSERVATIONS

Nest Excavation

At the time of discovery, a male northern sooty woodpecker was excavating a hole estimated to be 5-10 cm deep: implying that excavation may have started just 2-3 days prior to discovery. After 40 minutes of excavation, the male switched roles with the female. The female then excavated for at least 10 minutes before leaving. On 10 March 2022, almost 3 ⁄ 4 of the woodpecker’s body could now fit into the cavity with the tail protruding at a sharp angle, indicating the ongoing vertical deepening of the nest. On 18 May 2022, both the male and female fully entered the nest on separate occasions and excavated from the inside. We observed the process of nest excavation for a total of 20.72 hours on six different days from 23 February to 18 March 2022. Excavation sessions lasted between 9 to 72 minutes before one of the pair left and the other took over the duty. We noted that the excavating individual usually called once or twice before switching roles with its partner. Both members of the nesting pair contributed to nest building: the male however, excavated the cavity seven times longer in a day (4.97 hours) compared to the female (0.67 hours) ( Fig. 2 ).

Diurnal Incubation/Brooding

Observations from 11-12, 15 & 17 April 2022 (16.02 hours), revealed that both parents contribute to diurnal incubation/brooding as evident from the observed prolonged stays of the adults inside the cavity. During a full day observation (06:00-18:00) on 11 April, we recorded that the male stayed inside the cavity for 4.12 hours whereas the female for 3.42 hours. On 14 April, at 18:31, the male was last seen entering the cavity and may have been the one incubating during the night, as is the case with most woodpecker species ( Winkler & Christie, 2020).

Nestling Provisioning and Nest Sanitation

On 4-5 May 2022 (16.92 hours), we observed two nestlings peeking from the cavity opening ( Fig. 3 ). The nestlings were black and fully feathered with a slightly whitish breast area. They have short, sturdy, yellowish white bills, and whitish lores, auriculars, and supercilia. During this time, both adult woodpeckers were actively delivering food to the nestlings. Food delivery was done through regurgitation while the adult was perched at the rim of the cavity. On 5 May (06:00-18:00), we recorded 11 feeding instances; five were done by the male and six by the female. Per feeding event, we observed both adult parents fully entering the cavity and exiting 2-3 minutes later with a faecal sac in the bill. We recorded eight instances of faecal sac removal; five were done by the female and three by the male ( Fig. 2 ). On 14 May at 05:45, the nest was already inactive. We posit that the woodpeckers fledged between 6 and 13 May. During this time, we also noted a pair of green racquet-tail parrots Prioniturus luconensis inspecting the empty cavity nest for approximately 20 minutes.

Figures

Fig. 1 - Cavity nest excavated by the northern sooty woodpecker: a) nest entrance; b) nest contents. / Nido scavato dal picchio fuliggi- noso: a) ingresso del nido; b) contenuto del nido. (Photo: / Foto: Erwin S. Quijano, 29 May 2022).

Fig. 2 - Contribution of male and female northern sooty woodpecker to different breeding activities in one full daylight observation period (06:00-18:00). Nest building and brooding efforts were expressed as proportions of time spent (%) from total observation hours whereas feeding and faecal sac removal as proportions of counts (%) from total number of incidences./ Contributo del maschio e della femmina di picchio fuligginoso alle diverse attività riproduttive durante un intero periodo di osservazione diurna (06:00-18:00). Lo sforzo per la costruzione del nido e la cova è stato espresso come proporzione del tempo trascorso (%) rispetto al totale delle ore di osservazione, mentre l’alimentazione e la rimozione delle sacche fecali come proporzione dei conteggi (%) rispetto al numero totale di incidenze.

Fig. 3 - Northern sooty woodpecker nestlings peeking at the entrance of the cavity nest on 5 May 2022. / Nidiacei di picchio fuliggi- noso che sbirciano dall’ingresso della cavità del nido il 5 maggio 2022. (Photo: / Foto: Jhaynhell Fidelino).