Pied-billed Grebe (Podilymbus podiceps)

Pied-billed Grebe

Description

The pied-billed grebe (Podilymbus podiceps) is a species of the grebe family of water birds. Because the Atitlán grebe (Podilymbus gigas) has become extinct, the Pied-Billed Grebe is now the sole extant member of the genus Podilymbus. The pied-billed grebe is primarily found in ponds throughout the Americas. Other names of this grebe include American dabchick, rail, dabchick, Carolina grebe, devil-diver, dive-dapper, dipper, hell-diver, pied-billed dabchick, pied-bill, thick-billed grebe, and water witch. Pied-billed grebes are small, stocky, and short-necked. They are 31–38 cm (12–15 in) in length, with a wingspan of 45–62 cm (18–24 in) and weigh 253–568 g (8.9–20.0 oz).[10] They are mainly brown, with a darker crown and back.[11] Their brown color serves as camouflage in the marshes they live in.[12] They do not have white visible under their wings when flying, like other grebes.[13] Their undertail is white[11] and they have a short, blunt chicken-like bill that is a light grey color,[11] which in summer is encircled by a broad black band (hence the name). In the summer, its throat is black. There is no sexual dimorphism.[13] Juveniles have black and white stripes and look more like winter adults. This grebe does not have webbed feet. Its toes have lobes that come out of the side of each toe. These lobes allow for easy paddling. When flying, the feet appear behind the body due to the feet's placement in the far back of the body.[11]

Threats

They are extremely sensitive to disturbances, especially by humans. While breeding, if scared, adults may abandon their nests without protecting the eggs. The waves from boats can destroy the nests and their sounds easily frighten the birds.[12]

Distribution And Habitat

The Pied-billed Grebe occurs throughout the Western Hemisphere including the West Indies (Raffaele and others 1998). In Puerto Rico, the species is a common resident in wetlands, ponds, and reservoirs in the coastal plain and lowlands (Oberle 2018). It also occurs on Culebra and Vieques (PRDNER 2015, Saliva 1994, Sorrié 1975, Ventosa-Febles and others 2005), in the latter being a rare resident (Gemmill 2015). The atlas fieldwork yielded a total of 157 records within 89 hexagons or 18 percent of the 479 total hexagons (see map). Of the 89 hexagons where this species occurs, breeding met the atlas definition of confirmed in 28 percent (25) of the hexagons, probable in 16 percent (14), and possible in 56 percent (50) (see map).

Breeding Habits

The Pied-billed Grebe builds a fl oating nest among emergent vegetation (Raffaele and others 1998). Previously published reports indicate that it breeds throughout the year, but mostly from March to July (Raffaele and others 1998). Atlas results show that this species breeding season extends throughout the year with most breeding activity from March to June (see chart). Pied-billed Grebe distribution. The map shows the highest breeding code by hexagon and overlaying the ecological life zones in Puerto Rico. Note: percentages may not total 100 due to rounding. 39Pied-billed Grebe/ZaramagoThe breeding activity peaks during March and June, and it mostly takes place within the subtropical moist forest life zone (see chart). Results show that this species breeds mostly within the subtropical moist forest life zone (74 percent of the hexagons) throughout the island. However, results indicate that it also breeds in the subtropical dry forest life zone (20 percent of the hexagons), and subtropical wet and lower montane wet forest life zones (6 percent of the hexagons) (see table and map).

Conservation

The current population trend of the Pied-billed Grebe is described as stable, although some populations have unknown trends (Wetlands International 2012). This species is currently listed as a species of least concern by the IUCN (BirdLife International 2016). Locally, this species is not listed in any of the threatened categories of PRDNER and USFWS. In Puerto Rico, the Pied-billed Grebe has a protected habitat in land of 12 percent or 253 km2 of the total area covered by the hexagons where evidence of breeding was found for this species (2127 km2).