RETIRED
SPECIES

Tawny Antpitta Grallaria quitensis Scientific name definitions

Harold F. Greeney and Andrew J. Spencer
Version: 2.0 — Published September 1, 2023

Breeding

Introduction

Only four studies have reported on the nesting of the Tawny Antpitta, all pertaining to the nominate quitensis, in Napo and Pichincha, northeastern and northwestern Ecuador respectively (222, 169, 178, 187). To date, there are no nests described for either of the other two subspecies, and the information summarized here on the nests, eggs, and nesting behavior of the Tawny Antpitta pertains entirely to the nominate quitensis.

Phenology

Across its considerable range, there are records of immatures or nesting activity that suggest the breeding of the Tawny Antpitta occurs during all months of the year. At Papallacta in eastern Ecuador, however, breeding appears fairly seasonal (peak September–December). This coincides with generally milder weather and less precipitation in this area (187). This period is also marked by the mass emergence of scarab beetle adults ("catzos"), which are so numerous they are often harvested for food by humans (G. Buitrón-Jurado in 8), and possibly provide an important resource for the Tawny Antpitta. Despite the plethora of breeding records (for an antpitta), more data are needed before seasonality can be described in any particular region.

Details of Breeding Records

The large majority of the following records are from specimens and photographs examined by Greeney (8). Other published records are derived from Salvadori and Festa (37), Goodfellow (119), Domaniewski and Sztolcman (10), Berlioz (206), Olivares (83, 27), Hilty and Brown (24), Fjeldså and Krabbe (23), Greeney and Martin (169), Greeney and Harms (178), Greeney et al. (187), and Greeney (9). Specific details for all records, such as location and dates, are included in Greeney (8).

Grallaria quitensis alticola

  • COLOMBIA: Fledglings - October (n = 1). Juveniles - June (n = 2), July (n = 1), August (n = 1), December (n = 2). Subadults - April (n = 1). Adults carrying food - June (n = 1). Breeding condition - August (n = 1).

Grallaria quitensis quitensis

  • COLOMBIA: Adults carrying food - November. Fledglings - March (n = 1), April (n = 1), May (n = 1). Fledglings transitioning - April (n = 1), September (n = 1). Juveniles - Janurary (n = 1), February (n = 1), March (n = 4), May (n = 1), September (n = 3). Juveniles transitioning - March (n = 1), April (n = 1), June (n = 1), November (n = 1). Subadults - February (n = 1), March (n = 2), September (n = 1), October (n = 1). Adults in breeding condition - February (n = 1).
  • ECUADOR: Building - February (n = 1), August (n = 1), October (n = 2), September (n = 2), December (n = 1). Laying - August (n = 1), October (n = 3). Incubation - February (n = 1), September (n = 5), October (n = 7), November (n = 1). Nestlings - January (n = 1), February (n = 2), October (n = 3). Adults carrying food - January (n = 1), February (n = 1), October (n = 1), December (n = 1). Fledglings - January (n = 1), February (n = 3), May (n = 1). Fledglings transitioning - February (n = 1), November (n = 1). Juveniles - January (n = 7), February (n = 5), April (n = 6), May (n = 1), June (n = 2), July (n = 3), August (n = 1), September (n = 1), October (n = 3), November (n = 3). Juveniles transitioning - March (n = 3), April (n = 2), June (n = 3), September (n = 5). Subadults - February (n = 3), April (n = 1), May (n = 2), July (n = 3), August (n = 2), October (n = 2), December (n = 1).
  • PERU: Juveniles - August (n = 2). Subadults - July (n = 1).

Grallaria quitensis atuensis

  • PERU: Female with an unshelled egg - September (n = 1). Subadults - September (n = 1).

Nest Site

Selection Process

No information.

Nesting Habitat

Most of the studies describing the nesting biology of the Tawny Antpitta have focused on populations inhabiting areas at or above treeline, perhaps leading to the presumption that this species nests only in open, wind-swept paramo and bunch-grass habitats . It does, however, also nest within the dark understory of dense, moss-covered Polylepis forest, as illustrated by nests found in the Yanacocha Reserve in northwest Ecuador (checklist S98034425; ). As noted by Greeney and Martin (169), within any given pair’s territory, old nests and the currently active nest tend to be clustered, almost always associated with relatively isolated vegetation and usually on the leeward side of ridges where they receive most shelter from wind and weather.

Site Characteristics

Nesting Substrates

Favored substrates include Gynoxys [acostae], Loricaria antisanensis (both Asteraceae) and Hypericum laricifolium (Clusiaceae), and bunch-grass (Festuca sp., Poaceae). Thirty-four nests (169, 8), were constructed in the following plants: H. laricifolium (n = 13), G. acostae (n = 13), Festuca sp. (n = 3), L. antisanensis (n = 2), Pentacalia sp., Asteraceae (n = 1), Baccharis sp., Asteraceae (n = 1), unknown (n = 1). Based on many hours searching for nests, Greeney (8) suggested that bunch-grass is utilized more frequently than these data suggest, but that such nests are more easily overlooked.

Nest Placement

Most nests are roughly centrally located in the substrate and often only partially concealed by sparse foliage (169).

Nest Height

Nest height of 34 nests (169, 8) ranged from 0.55 to 2.5 m above the ground (mean ± SD, 1.2 ± 0.5 m).

Nest

Construction Process

It is not known, but it is presumed that both genders are involved in nest-site selection and construction. Video observations (8) have shown, however, that both genders add lining material to nests during incubation.

Structure and Composition

The nest of the Tawny Antpitta is a bulky, thick-walled, proportionately deep, open cup (8). Originally, the nests of the Tawny Antpitta were described as bulky cups of moss, mud, and small sticks, sparsely lined with pale grass stems (169). However, Greeney (8), amended this description by postulating that the "mud" seen in some nest walls is frequently, if not always, a result of repeated use of the same nests, resulting in the decomposition of previously added materials. There are no published observations of nest construction by the Tawny Antpitta, but if it turns out that they actually bring mud to the nest, this would be the only known case of mud being used in the nest of any antpitta (179, 8).

Dimensions

Measurements of 34 nests (169, 8) are: external diameter 19–30 cm, mean 22.5 ± 2.9 cm; external height 10–16 cm, mean 13.0 ± 0.9 cm; internal diameter 10–13 cm, mean 11.2 ± 0.7 cm; internal depth 6.0–7.5 cm, mean 6.3 ± 1.0 cm.

Microclimate

No data.

Maintenance or Reuse of Nests

During incubation, both adults occasionally bring nesting material, usually fine materials, and add them to the lining of the nest (see Incubation).

Eggs

Shape

Eggs are short-subelliptical (236), similar in shape to eggs of other antpittas (179, 8).

Size

Mean egg measurements (n = 17 eggs, all quitensis) are 30.7 ± 0.8 × 24.5 ± 0.8 mm (169, 178, 8).

Mass

The weights of two eggs from a single clutch were 8.5 g and 10.3 g, measured with incubation already underway (169).

Eggshell Thickness

No data.

Color and Surface Texture

The eggs of the Tawny Antpitta are semi-glossy with a sky-blue to blue-green ground color. They are, however, somewhat variably marked, ranging from completely unmarked, to bearing a few scattered cinnamon flecks and small spots, or having heavier (but still relatively sparse) cinnamon and lavender flecks and blotches scattered across the egg. Most eggs with markings tend to have the spots concentrated near the larger pole some degree (169, 8).

Clutch Size

At present, all known clutches of the Tawny Antpitta have been of two eggs (169, 178, 8).

Laying

Laying has only been carefully monitored at one nest (178). At this nest, the first egg was laid at ca. 1600 h and the second egg was laid ca. 48 hours later (178). It appeared that the adult did not spend the night on the nest the night after clutch completion (8).

Incubation

Both pair members participate in incubation (169, 178), but the relative contributions of each sex are not known.

Onset of Broodiness and Incubation Patches

No information. Both sexes presumably develop incubation patches.

Incubation Period

Incubation lasted 21.5 days at one nest (178), but this is the only record of incubation period for the Tawny Antpitta.

Incubation Constancy

Greeney and Harms (178) documented limited and irregular incubation for the first three days after clutch completion. Across the entire incubation period, daylight coverage of the clutch was 44–97%, with the eggs covered only 44% of daylight hours on the day of clutch completion. Attendance on all subsequent days was over 64%, with a mean of 86% coverage across the incubation period if the first three days of irregular attendance are omitted. This is close to the 82% coverage documented for this species by Greeney and Martin (169), during only four hours of observation on a single day. Incubation bouts (n = 209) lasted a mean of 55 ± 37 min, while periods of absence (n = 164) lasted 12 ± 21 min (178). Like other antpittas (237, 238), the longest periods of absence usually occur around dawn.

Other Behaviors

Similar to other antpittas (179), the incubating Tawny Antpitta spends a measurable amount of time (3.9%) engaged in behaviors that likely reduce their ability to remain vigilant. Similar behaviors were also described for this species at nests studied by Greeney and Martin (169). Bouts of activity on the nest, when adults engaged in one of the various behaviors described below, may occur as frequently as 10–11 times/h or every 5–6 min. During 27% of a total of 2,158 movement bouts, Greeney and Harms (178) observed the adults lean into the nest and probe at the nest lining, either with sharp pecks or with the sewing-machine-like movement described for other passerines (239, 240), including antpittas (241, 242). Twenty-eight percent of nonvigilant time on the nest was spent arranging material therein, while a relatively small amount of time (5%) was dedicated to preening or rufflling the feathers. The incubating adult sometimes close its eyes and appear to doze off, occasionally opening its bill widely but silently, presumably yawning (169). When returning to the nest, either to spell its partner or get back onto the eggs, the adult often brings a piece of lining material that is unceremoniously dropped into the nest before settling over the eggs (28% of 229 arrivals; 178). While incubating, the adult vocalizes frequently. Individual bouts of singing (with > 30 s between vocalizations) usually begin with soft, one or two-note versions of the normal song (see Vocalizations). Songs increase in volume slowly, and the bout of vocal activity usually ends with one or more typical, full-volume, three-note songs. Often the singing adult alternates between two- and three-note songs (169). Singing bouts range in duration from single songs to repeated songs (at 4–10 s intervals) spanning four minutes or more and delivered at rates of up to 17 songs/min. At the nest studied by Greeney and Harms (178), adults sang at a rate of 4.5 songs/h across the entire incubation period. In addition to delivering two- or three-note songs, adults occasionally gave a single-note keeyurr!, usually in response to similar calls heard away from the nest. It has been suggested that these calls, at least when given from the nest, function to inform mates of their location and status (8), but are also apparently given in alarm (see Vocalizations). While vocalizing, the adult strains its neck upwards, pointing its bill at an angle towards the sky as described for singing adults away from the nest, but the incubating adult always remais in apparent contact with the eggs (169).

Hatching

The two eggs of a single clutch hatched within 30 min of each other, at ca. 1015 h and 1045 h (178). No further information.

Young Birds

Condition at Hatching

Nidicolous. Based on previously published photographs (9), the hatchling Tawny Antpitta has its eyes closed, is pink-skinned, and bears dorsal patches of long gray natal down.

Growth and Development

Little information. A few days after hatching, the nestling develops a covering of dense post-natal down (9). See Plumages.

Parental Care

There are no published studies on the parental care of the Tawny Antpitta. Nestling period at one nest may have been 15 or 16 days (8). Compared to the longer nestling periods of many congeners (179), this seems rather short, especially considering the low temperatures faced by this paramo-nesting species. Further observations are certainly warranted before a nestling period of 15–16 days can be accepted.

Cooperative Breeding

So far as is known, the Tawny Antpitta does not have helpers at the nest.

Brood Parasitism by Other Species

None reported.

Fledgling Stage

Information needed.

Immature Stage

Information needed.

Recommended Citation

Greeney, H. F. and A. J. Spencer (2023). Tawny Antpitta (Grallaria quitensis), version 2.0. In Birds of the World (N. D. Sly, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.tawant1.02