. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. New data on the Hierro Giant lizard 443 A* Sector I (Pino) S- Sector II (CoIcosa) •37%. 4 5 6 7 8 9 /0 // 5 6 7 8 9 /0 // EXCREMENT DIAMETERS IN MM. Fig. 13: Bar-chart showing frequency of excrement diameter classes in Hierro Giant lizard on (A) Sector I and (B) Sector II of habitat. with binoculars of 20 x 80). Martínez Rica (1982) measured indirectly two old males (62 ±2 cm and 71 ±5 cm) with a greyish pileus because of age. If we accept a "very big" cat
. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. New data on the Hierro Giant lizard 443 A* Sector I (Pino) S- Sector II (CoIcosa) •37%. 4 5 6 7 8 9 /0 // 5 6 7 8 9 /0 // EXCREMENT DIAMETERS IN MM. Fig. 13: Bar-chart showing frequency of excrement diameter classes in Hierro Giant lizard on (A) Sector I and (B) Sector II of habitat. with binoculars of 20 x 80). Martínez Rica (1982) measured indirectly two old males (62 ±2 cm and 71 ±5 cm) with a greyish pileus because of age. If we accept a "very big" category for the head I observed, and another for the unseen young of the year, proportions would be 0 : 2 : 8 : 5 : 1. An indirect approach was also taken to estimate population structure. The excrement diameter of a given lizard should be approximately constant if diet does not change much, varying principally in length depending on the amout of food ingested. Thus, a frequency analysis of excrement diameter classes could give us an inferred view of the whole population structure. All excrements (perhaps deposited in a period of 2—2V2 months), that were not old (disintegrated, bleached by sun, etc) were sampled and measured with a calibrator: 110 in sector I and 50 in sector II. Figures 13 A and 13 B show the respective size frequency distribution obtained. The proportion of young from this exercise gives %, less than observed in the field (1 : 8). Even so, both cases indicate that we are probably dealing with a collapsing population. The Hierro Giant lizard has to be considered in extreme danger of extinction. Reproduction Some female lizards observed and photographed (600 mm Novoflex telephotolens) in the field were clearly identified to be pregnant, but doubts arise in other cases. Therefore, I only trust the proportion obtained from the four females collected, of which three were pregnant. The bulges on the flanks could be easily observed and counted (figs. 15 an
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