Titicaca Flightless Grebe
Encyclopedia
The Titicaca Grebe or Titicaca Flightless Grebe (Rollandia microptera) is a grebe
found on the altiplano
of Peru
and Bolivia
. As its name implies, its main population occurs on Lake Titicaca
. Lake Uru Uru and Poopó, the Rio Desaguadero
, and small lakes that connect to Lake Titicaca in wet years, serve as "spillovers" territory. In the past, the population was larger and several of these lakes – such as Lakes Umayo
and Arapa
– apparently had and may still have permanent large colonies (BirdLife International 2006). It is sometimes placed in Podiceps
or a monotypic
genus
Centropelma. Its local name is zampullín de Titicaca.
which is not found in South America. The only congener
, the White-tufted Grebe
, does not look very similar. The color pattern of the Titicaca Grebe is altogether similar to that of the Red-necked Grebe, but it has a darker belly, and a white (not light grey) throat patch that runs down the neck nearly to the breast. Due to the short wings, the rufous flanks can usually be seen. The ornamental plumes on the head are a vestigial version of those of the White-tufted Grebe, but dark. Iris
and the lower bill are yellow. Juveniles and non-breeding adults are duller, lack the ornamental plumes, and in the case of the former have rufous stripes on the sides of the head and more white on the neck, so that the rufous breast does not show in swimming birds.
It is entirely flightless, but will use wing-assisted running over considerable distances. It is an excellent diver, reaching a burst speed of 3.5 km/h (2 knots).
(Schoenoplectus californicus ssp. tatora). Other plants are the underwater Myriophyllum elatinoides and Hydrocharitaceae
water weeds, and the floating duckweeds and Azolla. Potamogeton
constitute the dominant underwater vegetation in the deeper parts, down to 14 m (some 45 ft).
pupfish of the Titicaca drainage. The introduced silversides
Odontesthes bonariensis (pejerrey) is not usually taken. As the grebe only eats prey smaller than some 15 cm (6 in), the adult pejerrey which are of commercial interest are not part of its diet as they are far too large.
gill nets in the 1990s. It was confirmed (Martinez et al. 2006) that the mortality of grebes drowning in these nets is considerable, killing potentially thousands of individuals each year in 2003. Obviously, the 2001 survey which detected very low numbers was flawed for some reason and the species must be more common simply to sustain such losses. In 2003, the number of individuals was estimated to be over 2,500, with more than 750 mature birds, possibly as many as 1,500. This still is a marked decline from the pre-1990s figures.
The IUCN currently lists its threat status as EN A2cde+3cde; D. The "D" qualifier is not appropriate according to the latest results. Its addition was based on a pessimistic scenario based on the 2001 field data (that the bird was near-extinct on Lake Titicaca, from which there was insufficient data then). Instead, the classification would be EN A3cde; C2a(i) or EN C1+2a(i), depending on how population numbers have developed since then. In any case, the 2003 survey indicated that subpopulations are fragmented, with probably no more than about 100 pairs occurring in any one area. It is not known how much the grebes move about until establishing breeding territories, but presumably, the species is fairly sedentary due to its flightlessness.
), it may abandon habitat due to pollution and boat traffic; on the other hand, the delta of the Rio Coata at the northern end of Puno Bay seems prime habitat at least seasonally (Martinez et al. 2006). Overharvesting of reeds will also drive the birds from an area, but generally the threat of unsustainable use of totora is of less significance, at least in the short term. It is notable that the species evolved on the lake and has sustained several periods of rather pronounced climate change
in addition to the normal ENSO
. It apparently possesses a quite good capability to recover from population declines, which seems an adaptation to the fluctuating habitat availability even during periods of stable climate, as the lake routinely floods and recedes from considerable areas. Apparently, population numbers reached a low point in 1999 due to a severe drought following the "mega-ENSO" of 1997/1998, and have somewhat recovered since then.
It is interesting to note that pejerrey fishery occurs mostly in waters too deep to be utilized by the grebes. While the coarser gill nets used for fishing pejerrey are technically more of a threat to the sizable grebes than the finer ones preferred for Orestias, the latter will still catch and drown especially young and unexperienced birds, and probably even attract these due to holding their favorite food. O. bonariensis is not only one of the two major hauls of the local fishing industries, but places a strain on the Orestias stocks. Insofar, a shift by the fishermen from Orestias to the silversides is likely to benefit them, the grebes, and the entire lake ecosystem.
Grebe
A grebe is a member of the Podicipediformes order, a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter...
found on the altiplano
Altiplano
The Altiplano , in west-central South America, where the Andes are at their widest, is the most extensive area of high plateau on Earth outside of Tibet...
of Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
and Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
. As its name implies, its main population occurs on Lake Titicaca
Lake Titicaca
Lake Titicaca is a lake located on the border of Peru and Bolivia. It sits 3,811 m above sea level, making it the highest commercially navigable lake in the world...
. Lake Uru Uru and Poopó, the Rio Desaguadero
Desaguadero River (Bolivia)
The Desaguadero River in Peru and Bolivia is the river that drains Lake Titicaca. It exits the lake at the southern part of the river basin, it flows south and drains approximately five percent of the lake's flood waters into Lake Uru Uru and Lake Poopó....
, and small lakes that connect to Lake Titicaca in wet years, serve as "spillovers" territory. In the past, the population was larger and several of these lakes – such as Lakes Umayo
Lake Umayo
Lake Umayo is a lake in the Puno Region of Peru. The shores of the lake house Sillustani burial ground....
and Arapa
Lake Arapa
Lake Arapa is a lake in Juliaca District in San Román Province in the Puno Region of Peru. It is located 40 km from Juliaca....
– apparently had and may still have permanent large colonies (BirdLife International 2006). It is sometimes placed in Podiceps
Podiceps
Podiceps is a genus of birds in the grebe family.It has representatives breeding in Europe, Asia, North and South America. Most northern hemisphere species migrate in winter to the coast or warmer climates....
or a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Centropelma. Its local name is zampullín de Titicaca.
Description
This is a mid-sized grebe, varying from 28-45 cm in overall length. It weighs up to 600 g. Its coloration is unmistakable. The only grebe species it somewhat resembles is the unrelated Red-necked GrebeRed-necked Grebe
The Red-necked Grebe is a migratory aquatic bird found in the temperate regions of the northern hemisphere. Its wintering habitat is largely restricted to calm waters just beyond the waves around ocean coasts, although some birds may winter on large lakes...
which is not found in South America. The only congener
Congener
Congener has several different meanings depending on the field in which it is used. Colloquially, it is used to mean a person or thing like another, in character or action.-Biology:In biology, congeners are organisms within the same genus...
, the White-tufted Grebe
White-tufted Grebe
The White-tufted Grebe is a species of grebe in the Podicipedidae family.It is found in Argentina, Bolivia, Brazil, Chile, Falkland Islands, Paraguay, Peru, and Uruguay.Its natural habitat is freshwater lakes.-References:...
, does not look very similar. The color pattern of the Titicaca Grebe is altogether similar to that of the Red-necked Grebe, but it has a darker belly, and a white (not light grey) throat patch that runs down the neck nearly to the breast. Due to the short wings, the rufous flanks can usually be seen. The ornamental plumes on the head are a vestigial version of those of the White-tufted Grebe, but dark. Iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
and the lower bill are yellow. Juveniles and non-breeding adults are duller, lack the ornamental plumes, and in the case of the former have rufous stripes on the sides of the head and more white on the neck, so that the rufous breast does not show in swimming birds.
It is entirely flightless, but will use wing-assisted running over considerable distances. It is an excellent diver, reaching a burst speed of 3.5 km/h (2 knots).
Distribution and habitat
The Titicaca Flightless Grebe occurs in a habitat mosaic in relatively shallow waters (up to about 10 m/35 ft deep). The reed belt is found in water of up to 4 m (13 ft) deep and constitutes the breeding habitat. It is made up mainly of TotoraTotora (plant)
Totora is a subspecies of the giant bulrush sedge. It is found in South America - notably on Lake Titicaca, the middle coast of Perú and on Easter Island in the Pacific Ocean...
(Schoenoplectus californicus ssp. tatora). Other plants are the underwater Myriophyllum elatinoides and Hydrocharitaceae
Hydrocharitaceae
Hydrocharitaceae is a flowering plant family that includes a number of species of aquatic plant, broadly called the Tape-grasses, and includes the well known Canadian Waterweed and Frog's Bit.The family includes both fresh and marine aquatics...
water weeds, and the floating duckweeds and Azolla. Potamogeton
Potamogeton
Potamogeton is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed...
constitute the dominant underwater vegetation in the deeper parts, down to 14 m (some 45 ft).
Diet
This species, like all grebes, feeds mainly on fish. Nearly 95% of prey mass is made up by the OrestiasOrestias (Cyprinodontidae)
Orestias is a genus of pupfish. Older systematics classified them into the own family Orestiidae. They are carnivorous plankton feeders and can reach a length between 9 and 22 centimetres. Their most characteristic feature is the absence of the ventral fin...
pupfish of the Titicaca drainage. The introduced silversides
Neotropical silversides
The neotropical silversides are a family Atherinopsidae of fish in the order Atheriniformes. The approximately 104 species in 13 genera are distributed throughout the tropical and temperate waters of the New World, including both marine and freshwater habitats...
Odontesthes bonariensis (pejerrey) is not usually taken. As the grebe only eats prey smaller than some 15 cm (6 in), the adult pejerrey which are of commercial interest are not part of its diet as they are far too large.
Reproduction
It is likely that each pair which holds a territory attempts to breed once per year. The period in which the parents care for the young is probably rather prolonged, and there is possibly no fixed breeding season. Young birds become independent probably at somewhat less than 1 year of age, and there are usually 2 young per clutch, but there may be up to 4. Altogether, although more birds are found to incubate around December than at other times, about half the adult population seems to be breeding or caring for young at any time.Conservation status
It is classified by the IUCN as Endangered, with a population of less than 750 adults (BirdLife International 2006). Censuses in the latter part of the 20th century revealed that the population had declined from several thousand coincident with the introduction of monofilament lineMonofilament line
Monofilament fishing line is fishing line made from a single fiber of plastic. Most fishing lines are now monofilament because monofilament fibers are cheap to produce and are produced in a range of diameters which have different tensile strengths...
gill nets in the 1990s. It was confirmed (Martinez et al. 2006) that the mortality of grebes drowning in these nets is considerable, killing potentially thousands of individuals each year in 2003. Obviously, the 2001 survey which detected very low numbers was flawed for some reason and the species must be more common simply to sustain such losses. In 2003, the number of individuals was estimated to be over 2,500, with more than 750 mature birds, possibly as many as 1,500. This still is a marked decline from the pre-1990s figures.
The IUCN currently lists its threat status as EN A2cde+3cde; D. The "D" qualifier is not appropriate according to the latest results. Its addition was based on a pessimistic scenario based on the 2001 field data (that the bird was near-extinct on Lake Titicaca, from which there was insufficient data then). Instead, the classification would be EN A3cde; C2a(i) or EN C1+2a(i), depending on how population numbers have developed since then. In any case, the 2003 survey indicated that subpopulations are fragmented, with probably no more than about 100 pairs occurring in any one area. It is not known how much the grebes move about until establishing breeding territories, but presumably, the species is fairly sedentary due to its flightlessness.
Threats
Apart from drowning in gill nets, other threats are probably only relevant in the short run, locally, or if several should manifest simultaneously. Eggs may be collected by locals on a small scale, and this is probably sustainable. Adult birds are not usually hunted as they taste of rancid fish like all grebes. Locally (e.g. around PunoPuno
Puno is a city in southeastern Peru, located on the shore of Lake Titicaca. It is the capital city of the Puno Region and the Puno Province with a population of approximately 100,000. The city was established in 1668 by viceroy Pedro Antonio Fernández de Castro as capital of the province of...
), it may abandon habitat due to pollution and boat traffic; on the other hand, the delta of the Rio Coata at the northern end of Puno Bay seems prime habitat at least seasonally (Martinez et al. 2006). Overharvesting of reeds will also drive the birds from an area, but generally the threat of unsustainable use of totora is of less significance, at least in the short term. It is notable that the species evolved on the lake and has sustained several periods of rather pronounced climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
in addition to the normal ENSO
El Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
. It apparently possesses a quite good capability to recover from population declines, which seems an adaptation to the fluctuating habitat availability even during periods of stable climate, as the lake routinely floods and recedes from considerable areas. Apparently, population numbers reached a low point in 1999 due to a severe drought following the "mega-ENSO" of 1997/1998, and have somewhat recovered since then.
It is interesting to note that pejerrey fishery occurs mostly in waters too deep to be utilized by the grebes. While the coarser gill nets used for fishing pejerrey are technically more of a threat to the sizable grebes than the finer ones preferred for Orestias, the latter will still catch and drown especially young and unexperienced birds, and probably even attract these due to holding their favorite food. O. bonariensis is not only one of the two major hauls of the local fishing industries, but places a strain on the Orestias stocks. Insofar, a shift by the fishermen from Orestias to the silversides is likely to benefit them, the grebes, and the entire lake ecosystem.
External links
- Titicaca Flightless Grebe videos on the Internet Bird Collection
- BirdLife Species Factsheet. Retrieved 2006-JUN-12.
- IUCN RangeMapZambullidor del Titicaca. Article and photo at Casa del Corregidor.