Sore When I Press On Stomach

1: Case of the Junin Grebe

I rma Franke




Junín Grebe, Podiceps taczanowskii

Population Junín Grebe

The Junín Grebe, Podiceps taczanowskii, is a critically endangered species of restricted distribution in Peru because confinement in Lake Junin and its inability to fly. The population size of the diver has received attention and controversy for decades and is one of the populations that have focused greater number of censuses.

Red List of IUCN Species Amernazadas 2010.1 indicates that the diver "was extremely abundant in 1938 and was a far larger number 1961.En 1000 individuals in the 80 there were 250 birds, which dropped to 100 in 1992 and 50 in 1993. Extrapolations made in 1995 using other methodologies estimated 205 individuals. The breeding seasons of 1995-1996 and 1996-1997 failed, but two nests were achieved in 1997-1998. In August 1998 counted more than 20 individuals in 4 km ² the lake. Censuses conducted in late 2001 suggest a population of approximately 300 individuals, although this extrapolation of transects may be too optimistic. It is considered that even if this estimate is correct, represents the number of individuals after an excellent breeding season and the number of mature individuals could be half. Currently it is considered that the population can be estimated between 100 and 300 individuals (BirdLife 2010).

In surveys conducted since the 80 draws attention to the increases and decreases in number of individuals in very short periods of time, it would not be expected in the case of a species because it has a long service life and reduced investment in each reproductive season (O'Donnell & Fjeldsa 1997). Because the latter feature, if the population declines sharply, one would not expect rapid growth even in good conditions for reproduction.

Census by direct counting in 2001

Some of the differences in numbers of individuals obtained may be due to methodology, the area sampled lake to extrapolate the results and the time of year when the census was conducted. This conclusion can be reached by analyzing the results of censuses conducted in 2001 under Project "Conservation Plan to save from extinction Junín Grebe (Peru SA Walsh 2002) that has had little circulation.

In this project three censuses were conducted in May, August and December 2001 was used

total count method of individuals on a sampling frame consisting of square

side a mile (148 km2) comprising entire body of water (Fig. 1). It swept through the mirror surface water simultaneous work with three boats each carrying a team of two observers, one equipped with a GPS navigator and the coordinates of the sampling units. This method allowed not only to have divers, but to know its location on the lake This allowed isoline maps to analyze their spatial distribution in the lake.

Fig 1. Location map of sampling units


Fig 2. Isolines of distribution map of Junin Grebe-May 2001


Fig 3. Isoline map of the distribution of Junín Grebe - August 2001.



Fig 4. Isoline map of the distribution of Junín Grebe - December 2001.

As you can see from the table, in the three censuses there was a growing number of individuals, from 113 in May to 304 in December. This increase in the number of individuals in the central water body of the lake is due to two factors. First, in May breeding pairs are still nesting in the reeds and are not spotted when crossing the lake. Secondly, it strongly influences the water level. In May, the lake's water level is high, allowing divers to use small lakes located among the reeds play as both protection and therefore were not recorded in the census. In December, at the end of the dry season, the lake's water level is at its minimum, which is why divers are forced to leave the reeds and remain in the central water surface, facilitating their sighting. Results


three Junín Grebe census made in 2001

May 2001, 113 individuals, four juveniles
August 2001, 160 individuals, 0 juveniles
December 2001, 304 individuals, six juveniles


is important highlight two other aspects. The low recruitment rate found for 2001 1.97% coincide with expectations of a species with the characteristics described above, increased longevity and low rate of annual recruitment. Another notable aspect is the concentration of divers in three high-density cores. One might wonder whether these nuclei remain in time as they had slight variations between the three censuses conducted. This seems to be the case for the existence of these nuclei had already been warned by Francisco Tueros, local fisherman who worked for a long time supporting studies J. Fjeldsa in the area and by R. Valdivia, head of the Paracas National Reserve in the period in which censuses were conducted (personal communication).

The described results raise several questions among which should be highlighted:

1 .- The various surveys reported by BirdLife (2009) were conducted in different years, so it is not possible to confirm the population dynamics of divers among the cattails, and the central water body based on a methodology. Only supported by verbal communication from local people familiar with the lake. If confirmed, this dynamic as an annual cycle, the number of divers counted vary markedly by the time the census is conducted. The variations in numbers reported for the three censuses of 2001 are similar to the increases and changes considered reducing the population through the years. Would be the "reductions and increases" reported for Junin Grebe real changes?

2 .- Several of the censuses carried out since the 80's were based on counts made from the edge of the lake or the edge of the cattails,. Given the difficulty of distinguishing the Junin Grebe Blanquillo Grebe, Podiceps occipitalis , if they are within a certain distance even for experienced people apply the values \u200b\u200bobtained by these methods?

3. For gregarious species that occupy very small areas, which remained relatively stable during show changes year, would be valid to extrapolate results from surveys of small areas to larger areas without clearly knowing the area they occupy? How to select sampling units appropriately? Extrapolating back to the area should be calculated? For the southern half of the lake? In a smaller area? How to set?



References BirdLife International 2010. Podiceps taczanowskii . In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.1. . Downloaded on 29 March 2010.

O'Donnel, C. & J. Fjeldsa. 1997. Grebes. Status survey and conservation action plan.
IUCN / SSC Grebe specialist group. Cambridge: IUCN Publications Services Unit
Walsh
Peru SA 2002. Conservation Plan to save from extinction the Junin Grebe. Tell PROFONANPE.