Nestling development and data on nests and eggs of Topaza pella (Aves, Trochilidae) in Amapá state, northern Brazil

The Crimson Topaz, Topaza pella, is the least known of the two hummingbird species of this exclusively Amazonian trochilid genus, that also includes T. pyra. Most available information on T. pella nests, young and reproductive behavior is based on anecdotal observations from Guyana in the 1930s and 1950s. Here, we provide new data on nest description, eggs and parental care of T. pella, and the growth and development of two nestlings over a 22-day period. We studied four nests in areas of dense terra firme forest in the state of Amapá, Brazil. All nests were in forked branches of shrubs over water bodies, and had a cup-like form. One nest contained two elongated white eggs, and another, two nestlings, which had their development recorded until they left the nest.


PALAVRAS-CHAVE:
Amazônia, beija-flor, reprodução, beija-flor-brilho-de-fogo, cuidado parental Topaza is a hummingbird genus with only two known species, Topaza pyra (Gould, 1846) and Topaza pella (Linnaeus, 1758), both endemic to the Amazon region (Sick 1997;Piacentini et al. 2015). According to a recent revision, T. pella ranges from eastern Venezuela, through the Guyanas, Suriname, and into the Brazilian Amazonian states of Roraima, Amazonas, Rondônia, Amapá and Pará (Hu et al. 2000). Subsequent records, however, have extended the range of the species into northern Mato Grosso state, on the southern border of the Brazilian Amazon (Davis and Olmstead 2010).
Currently, the information available on the reproductive ecology of the Crimson Topaz, T. pella is sparse and fragmented, and the majority is derived from observations made in the early twentieth century in what was then British Guiana (now Guyana) (Nicholson 1931;Davis 1958), with VOL. 50(2) 2020: 138 -141 ACTA AMAZONICA the exception of the observations by Borges et al. (2004) from central Amazonia. The Crimson Topaz is the largest hummingbird in Brazil, with about 20 cm in total length, of which over half is tail (Sick 1997). It inhabits primary forest, being most frequently observed near streams (Davis 1958). The species is known to reproduce from January to April and July to November in Guyana; and from August to December in northern Brazil (Grantsau 1988). Male displays to females include zigzag flights, followed by a rapid plunge to where the female is perched, then the male hovers in front of the female, opening and closing the tail, and ruffling the feathers of the gular region in a way that causes them to change color (Sick 1997;Borges et al. 2004). Females build nests on branches (perpendicular, simple or forked) suspended at between 40 to 50 cm above the surface forest streams (Nicholson 1931). Nests have the form of a low cup (Simon and Pacheco 2005), and are constructed from the fibres surrounding Bombax seeds, while the nest exterior is covered with cobwebs (Schuchmann 1982;Grantsau 1988). Recorded clutch size is consistently of two eggs, white in color, and incubation duration may exceed 23 days (Nicholson 1931).
Here, we provide additional data on reproductive habitat and season, nest size, structure and location, nesting dates, clutch size and egg color and size of T. pella in the state of Amapá, in northern Brazil, and provide, for the first time, a description of nestling development from hatching to fledging.
Our observations were made in two areas on the southeastern Guiana Shield, in the state of Amapá, in the Amazon region of Brazil. One area was in the municipality of Serra do Navio (0°54'N, 51°59'W) (Serra do Navio from now on). The other area was within a conservation unit, the Reserva Extrativista Beija-Flor-Brilho-de-Fogo (RESEX from now on), in the municipality of Pedra Branca do Amapari (0°49'N, 52°11'W). The title of the RESEX is derived from the common name for T. pella in Portuguese, due to the abundance of the species in the area. Both areas are covered by dense terra firme forest, with floodplain forests along rivers, and are drained by the Amapari River (Drummond et al. 2008).
We found four nests overall, one in Serra do Navio, on 4th June 2013 (Nest 1), and three in RESEX in September and October 2013 (Nest 2, 3 and 4). All nests were located in dense terra firme forest, on the branches of shrubs that, in all cases, were overhanging forest streams approxinately 3 m wide and 1.2 m deep, all affluents of the River Amapari. We measured the three RESEX nests (Table 1). Nest 2 contained two eggs, of which we measured one. Nest 1 contained two recently-hatched nestlings. We monitored this nest daily for 22 days, between 14:00 and 15:00 h, which allowed us to record parental care, nestling development, and the period of nestling residence prior to leaving the nest. In September, Nest 2 contained two eggs, while Nest 3 contained one nestling. In October, we collected Nests 2, 3, and 4 along with the branches to which they were attached. All three nests were already abandoned, and were deposited in the Zoology Laboratory at Universidade Federal do Amapá.
All nests had the form of a low cup with a forked base (see Simon and Pacheco 2005 for nest type categories). The nests were made of a soft, elastic, fibrous material, formed from Bombax seed fibers, mixed with a liquid. Sick (1997) suggested that T. pella might use nectar, saliva or sap to glue the fibrous materials together. The nest was secured to the twig by an extension of the nest body, which partly covered the support branch, and by a secondary covering of spider webs, similar to the third class of Trochilid nests described by Ruschi (1949) (Figure 1a).
The eggs found in Nest 2 were elongated and white. Measurements from one egg were 14.6 mm × 10.4 mm, with an inverted pole (Figure 1b). We decided not to measure both eggs, so as not to interfere overly with the reproductive process of the female. At this same nest, we observed the female incubating the eggs, with part of her body outside the nest.
Nestling development was recorded over the entire 22day period during which we monitored Nest 1. When the nestlings hatched, their eyes were closed, they had yellow beaks and lacked down, which only appeared on the second day of monitoring (Figure 2a). By the 5 th day, the nestlings had increased in size, and down was more evenly spread across the body (Figure 2b). By the 9 th day their bodies had gained more muscle, the wings had taken shape and the skin became more firmer and darker (Figure 2c). On the 12 th day, the skin of both nestlings was darker, and pin feathers had begun to appear (Figure 2d). The nestlings' eyes opened only on or about day 16 and, at the same time, the beak became greyer and the first feathers appeared (Figure 2f ). On the 20 th day, nestling bodies were fully covered in feathers (Figure 2h). On the 22 nd day, the wing feathers were longer and nestling plumage appeared similar to that of an adult female ( Figure  2i). Both nestlings left the nest on the 23 rd day, even though they still had very short tails. During the entire period, only the female was observed feeding the nestlings.
The positioning of all four nests on branches overhanging water bodies is in agreement with the observation made by Nicholson (1931). The form, structure, and means of nest attachment, all follow the patterns described for the species by Schuchmann (1982) and Grantsau (1988), although this species does not cover the nest with fragments of lichens or mosses, as do many members of the family (Ruschi 1949). Although overlapping somewhat with records described by Grantsau (1988) from the north of Brazil (August-December), the nesting period of T. pella at our study area is more in keeping with that for populations in the Guianas (July-November). It is important to note that the part of northern Brazil where the majority of existing data concerning T. pella has been obtained is bisected by the Equator, so that some of the locations lie in the southern, and others in the northern hemisphere. Hence, despite their proximity, seasonal patterns may vary between sites more extensively than their close proximity might suggest.
Clutch size, color, and egg form all follow the patterns and characteristics described by Nicholson (1931) for the species, which invariably consists of two matte white elliptical eggs. However, size corresponds more to the findings of Grantsau (1988) (18 mm × 11.5 mm), than those of Nicholson (1931) (24 mm in length). Parental care (incubation, nestling provision and nest maintenance) was carried out solely by the female, as reported by Sick (1997) to be the case for all species of the family Trochilidae. That nestlings remained in the nest for 22 days is similar to what Nicholson (1931) reported − a fledging period of some 23-24 days for two nests encountered at Moraballi Creek, British Guiana, in August-November 1929. This is the first detailed observation of the nestling development of T. pella, including photographic documentation. Our study supplements existing information  concerning the species. However, knowledge gaps remain to be filled, including duration of the incubation period and territorial defense. Consequently, we encourage researchers and birders to seek out additional information on the reproductive ecology of T. pella.