ISRAEL JOURNAL OF ZOOLOGY, Vol. 33, pp. 69-71, printed March 1985

DEFENSIVE BEHAVIOUR IN A BOIGINE SNAKE: FIRST RECORD OF THROAT INFLATION IN PSAMMOPH/S

YEHUDAH L. WERNER Department of Zoology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel

Numerous species of the snake genus Psammophis Boie, 1827 (Colubridae: Boiginae) are common in Africa and southern Asia, mainly in arid and sandy habitats (Loveridge, 1940; Smith, 1943; FitzSimons, 1962; Reinhard & Vogel, 1975). In many parts of Israel (and of Sinai) Psammophis schokari (Forssk1ll, 1775) is one of the commonest snakes, whereas in southernmost Israel (and southern Sinai) P. aegyptius Marx, 1958 is quite common. Nevertheless I found no records of defensive behaviour in the genus, apart from concealment, escape and the tendency of some species to feign death and of many to bite when caught (FitzSimons, 1962; Pitman, 1974). The term "defensive" also embraces aggressive defenses - responses of a threatened animal which are aimed at repelling a potential predator, sometimes through warning or even bluffing (Edmunds, 1974). Carpenter and Ferguson (1977) found records of behavioural acts in 190 species belonging to 83 genera of colubrid snakes but none of Psammophis. I have caught or handled numerous individuals of P. schokari and a few P. aegyptius but have neither experienced nor heard of any particular defensive posture (other than escaping, defecating and biting), except for the following case. On 7 .IX.1980, aided by Mr. P. Amitai (Department of Zoology, Hebrew University of Jerusalem), I endeavoured to photograph a live adult P. aegyptius that was in his care. The snake's total length approximated 125 em, sex unknown (inPsammophis sex is unrecognizable externally due to the slenderness of the hemipenes (Smith, 1943; Dowling & Savage, 1960; FitzSimons, 1962)). The snake had been caught about a year earlier in the Neqiqe Ha-Mevokhim wadi, Sinai (ca. 15 km NW of the southern tip of the Peninsula). Mr. Amitai held the snake ca. 10 em behind its head over a mirror because I wanted the dorsal aspect and the brick-red ventral aspect to be seen together. (The venter is not red in all individuals of this species.) As I was approaching the head with the camera the snake began a (presumably) defensive display: it inflated its throat, exposing the whitish skin between the red gular scales, and at intervals of a few seconds repeatedly partly deflated, then reinflated it (Fig. I). This pumping was accompanied by a puffing sound, not high-pitched and not very loud but quite impressive at this close range. Although this unprecedented behaviour could conceivably represent a regular response directed towards conspecifics, here released by the mirror image, I was

Received 1 July 1984 and in revised form 31 December 1984 70 Y.L. WERNER Isr. I. Zool.

Fig. 1. An adult Psammophis aegyptius Marx (described in text) displaying throat inflation over a reflecting mirror. A. Throat almost maximally inflated. B. Throat partly deflated between bouts of inflation. impressed that the snake responded to the proximity of the camera. Other defensive responses in snakes also occur irregularly or individually (Werner & Frankenberg, 1982; Werner, 1983). If this display also occurs in individuals of other Psammophis species, it might perhaps explain the origin of the specific name of P. sibilans L. (hissing), the im­ propriety of which, for a usually silent snake, has aroused frequent protest (F. Werner, 1913; FitzSimons, 1962). In P. sibilans, whose throat is normally light yellow, the sound, if produced, may be more impressive than the sight. A defensive display of inflating the throat or the throat and neck has been reported in about 28 of the colubrid species reviewed by Carpenter and Ferguson (1977); others puff up even the whole body. Some of these displaying species are rear-fanged and mildly or even dangerously venomous, others are non-venomous; P. aegyptius is rear­ fanged and presumably (as judged from congeners) mildly or moderately venomous (Pitman, 1974). Our individual inflated only the throat, and that moderately; the sight was surprising because it was unexpected but actually much less impressive than in Dispholidus typus and Telothornis kirtlandii depicted by FitzSimons (1962: pls. 14-18) or Pseustes su/phureus and Spilotes pu/latus depicted by Rossman and Williams (1966). The latter authors noted an apparent correlation between the specific trait of neck inflation, and the anatomy of the respiratory system, viz., the length of the rudiment of the left-side lung in percra (percents of rostrum-anus length (Werner, 1971)) as reported by Brongersma {19 57) from preserved specimens. (Rossman and Williams misnamed this rudiment "tracheal lung.") In brief, according to Rossman and Williams (1966, as based on Brongersma, 1957), most or all of the few species of Colubridae in which the left lung exceeds 2 percra inflate the neck; the left lung in other species