Breeding biology of Hooded Gnateater Conopophaga roberti Hellmayr, 1905 (Aves: Conopophagidae)

Abstract

The Hooded Gnateater Conopophaga roberti Hellmayr, 1905 is an insectivorous understory passeriform with discrete behavior, whose reproductive attributes are poorly-known. In the present study, we describe the reproductive biology of the species and the growth pattern of the nestlings, based on observations conducted in remnants of the Cerrado savanna in eastern Maranhão state, in Brazil. The nests were identified during active searches conducted between June, 2018 and March, 2021. A total of 22 nests were found over the course of three breeding seasons. The cup-shaped nests were supported by small branches and were constructed at a mean height of 40.6 ± 16.1 cm (N = 21) above the ground. The nests were 23.1 ± 3.9 cm in length and 14.1 ± 1.6 cm in width (N = 21). The eggs were beige in color, with irregular brown mottling only at the rounded end of the egg, which had a mean length of 21.3 ± 0.8 mm, width of 17.2 ± 0.8 mm, and mass of 3.1 ± 0.1 g (N = 23). Hatchlings are completely naked and weigh 3.1 ± 0.2 g (N = 7), and when they abandon the nest, they have yet to reach full adult size, with the total length being 65.4% of that of the adult, the wing, 65.4%, the head, 73.9%, the culmen, 74.2%, the body mass, 73.3%, and the tarsus, 89.0% that of the adult. The growth curves are sigmoidal and all the coefficients of determination are at least 0.96, with the body length having the highest value (R2 = 0.98). During the breeding season, the adult pair emitted alarm calls constantly when observers were in the vicinity of the nest. On a number of occasions, members of the breeding pair were observed moving away from the nest as it was approached by observers, while engaging in broken-wing display. The nest architecture, the color of the eggs, and the behaviors presented by this gnateater were similar to those described for other Conopophaga. With this work we contributed to improve the knowledge on the breeding behavior of this poorly know group of understory insectivorous birds.

Full Issue

“…Our observations of adult female C. cearae expand the occurrence of this behaviour in the family. As noted by Greeney (2018), at least in C. aurita the postocular feathers can be used during this behaviour (see Leite et al 2012 (Hilty 1975, Lizarazo & Londoño 2022, C. lineata (Willis et al 1983) and C. roberti (Pereira et al 2022), nestlings fledge smaller and lighter than adults (Willis et al 1983, Lizarazo & Londoño 2022, when still unable to undertake long-distance flights (Pereira et al 2022), attaining near-adult size in c.2 weeks, but still with a short tail and small head and bill (Willis et al 1983). The young may remain with its parents for c.45 days post-fledging (Hilty 1975) when the plumage is still streaked but the tail reaches full length (Willis et al 1983).…”

Additional breeding data for Ceará Gnateater Conopophaga cearae, with a review of the breeding biology of the Conopophagidae

“…For C. melanops, Stenzel & Souza (2014) noted three successful nests of 13 monitored (23.07%) in a human-modified forest fragment in south-east Brazil (Rio de Janeiro), Lima & Roper (2009) reported four successful nests of 18 monitored (22%; survival rate 0.966 d -1 ) in a large protected area in south Brazil (Paraná), and Studer et al (2019) In these species, nest success is low mainly due to predation, desertion and environmental factors (Willis et al 1983, Marini et al 2007, Lima & Roper 2009, Stenzel & Souza 2014, Marini 2017, Studer et al 2019, Bodrati & Di Sallo 2020, Pereira et al 2022), but at least Willis et al (1983) also mentioned infertile eggs. Total production of young is usually low, 0.36 per adult in C. melanops in south Brazil (Lima & Roper 2009) and 0.58 per adult female for C. roberti in north-east Brazil (Pereira et al 2022). Studer et al (2019) reported daily survival rates for C. melanops during the incubation and nestling periods in north-east Brazil (0.922 d −1 and 0.958 d −1 ), with predation the only cause of failure during the latter period.…”

“…In common with many bird taxa in the Neotropics, the breeding biology of the Conopophagidae is poorly known (Xiao et al 2017, Greeney 2018) despite that basic information (e.g., nest and egg descriptions) exists for almost all species (Whitney 2003, Greeney 2018, del Hoyo et al . 2020, Lizarazo & Londoño 2022, Pereira et al . 2022).…”

“…Recent studies have contributed by adding new data or improving existing information for the breeding biology of some of the family (e.g., Studer et al . 2019, Bodrati & Di Sallo 2020, Lizarazo & Londoño 2022, Pereira et al . 2022, Alarcón et al .…”

“…Ceará Gnateater Conopophaga cearae represents one such gap, as there is, for example, no formal descriptions of the nest, eggs, nestling or fledgling (Greeney 2018, del Hoyo et al . 2020, Pereira et al . 2022).…”