6
CROP PROTECTION (1987) 6 (4), 265-270 Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits S. MORAN*, S. SOFERt AND M. COHEN q~ *Ministry of Agriculture, Department of Plant Protection and Inspection, Bet-Dagan, tMinistry of Agriculture Regional Office, Qiryat Shemona, and a~Jewish Agency, Zefat, Israel ABSTRACT. Populations of the rock hyrax, Procavia capensis, live in man-made rock terraces bordering fruit plots. They destroy fruit trees by browsing and by breaking branches. In an experiment to control these animals using fluoroacetamide-treated fruit baits, rock hyrax damage was completely prevented in all the treated plots. Introduction The rock hyrax, Procavia capensis syriaca Shreber 1784 (Figure 1), is found in Israel in the Negev, Dead Sea Valley, Jordan Valley, Mount Gilboa, Galilee Mountains and Mount Carmel regions (Maeltzer, 1973). Rock hyraxes live in families and prefer rocky terrain with plenty of natural crevices where they can roam by day and shelter at night. They easily climb trees (Maeltzer, 1973; Maeltzer and Livneh, 1982). In Western Galilee, agricultural plots have been created in the last decade by uprooting rocks which have then been pushed into long rows or terraces bordering the plots, thus forming suitable hiding- places for the rock hyrax (Figure 2). Hyraxes have thus been able to extend their distribution into new locations, far from the natural rock outcrop shelters. The plots have been planted with fruit orchards, some deciduous (mainly Pyrus spp.) and some subtropical (avocado, Persea americana Mill., and persimmon, Diospyros sp.). Hyraxes living in the terraces enter the plots and browse on the rows of trees adjacent to their rocky shelter (Moran, Sorer and Cohen, 1983), causing serious damage. Adult trees, that lose most of their leaves, yield almost no crop, and degenerate (Figures 3 and 4). Seedlings or 1- to 2-year-old subtropical trees also lose most of their leaves, their development is seriously impeded, and they may die (Figure 5). In deciduous seedlings the branches or the stems are bent under the weight of the hyraxes until they break near their base (Figure 6). Planting has had to be stopped until the hyrax problem could be solved (S. Moran, unpublished data). Fluoroacetamide (FAA) is an odourless water- soluble chemical. Although it is very toxic to most mammals (e.g. the LDs0 to Rattus norvegicus is 13 mg/kg (Bentley and Greaves, 1960) and 0.58 mg/kg to Meriones tristrami (Braverman, 1968), it causes no secondary poisoning of predators (Wolf, 1966), and is therefore used for control of field rodents in Israel (Wolf, 1977). It is less toxic to birds (Wolf, 1966). The lethal dose of FAA in the rock hyrax was found in preliminary tests to be 0.9 mg/kg (S. Moran, unpub- lished data). This means that the lethal dose for an adult hydrax, weighing 3-4 kg (Maeltzer and Livneh, 1982), is about 3mg a.i. FAA. In preliminary tests with baits of sorghum grains, alfalfa, apple leaves, chicken feed pellets, flour and apples, apple chips were found to be the only attractive bait to the rock hyrax (S. Sorer, unpublished data). Preliminary trials in rock hyrax control were con- ducted in the winter of 1981/82, using apple bait containing 0.01-0.02% FAA. In three out of four test plots no damage was recorded during the next spring and summer (Moran et aL, 1983). The experimental control operation described here was conducted in Western Galilee in June-August 1982. Materials and methods The 12 plots tested were located in the mountains of Western Galilee (Figure 7) in seven plantations, located at Elon, Avdon, Goren and Ya'ara (Table 1), in an area of 8 x 3 km (Figure 8). As each plot tested was populated by a family of rock hyraxes that moved freely along the terraces, it was impossible to divide it into control and treated plots: therefore, synchronous damage evaluation served as a control for the post-treatment data (see Table 3). Regular observations on the size of the hyrax 0261-2194/87/04/0265-06$03.00 © 1987 Butterworth& Co (Publishers)Ltd

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Page 1: Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits

CROP PROTECTION (1987) 6 (4), 265-270

Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits

S. MORAN*, S. SOFERt AND M. COHEN q~

*Ministry of Agriculture, Department of Plant Protection and Inspection, Bet-Dagan, tMinistry of Agriculture Regional Office, Qiryat Shemona, and a~Jewish Agency, Zefat, Israel

ABSTRACT. Populations of the rock hyrax, Procavia capensis, live in man-made rock terraces bordering fruit plots. They destroy fruit trees by browsing and by breaking branches. In an experiment to control these animals using fluoroacetamide-treated fruit baits, rock hyrax damage was completely prevented in all the treated plots.

Introduction

The rock hyrax, Procavia capensis syriaca Shreber 1784 (Figure 1), is found in Israel in the Negev, Dead Sea Valley, Jordan Valley, Mount Gilboa, Galilee Mountains and Mount Carmel regions (Maeltzer, 1973). Rock hyraxes live in families and prefer rocky terrain with plenty of natural crevices where they can roam by day and shelter at night. They easily climb trees (Maeltzer, 1973; Maeltzer and Livneh, 1982).

In Western Galilee, agricultural plots have been created in the last decade by uprooting rocks which have then been pushed into long rows or terraces bordering the plots, thus forming suitable hiding- places for the rock hyrax (Figure 2). Hyraxes have thus been able to extend their distribution into new locations, far from the natural rock outcrop shelters. The plots have been planted with fruit orchards, some deciduous (mainly Pyrus spp.) and some subtropical (avocado, Persea americana Mill., and persimmon, Diospyros sp.). Hyraxes living in the terraces enter the plots and browse on the rows of trees adjacent to their rocky shelter (Moran, Sorer and Cohen, 1983), causing serious damage. Adult trees, that lose most of their leaves, yield almost no crop, and degenerate (Figures 3 and 4). Seedlings or 1- to 2-year-old subtropical trees also lose most of their leaves, their development is seriously impeded, and they may die (Figure 5). In deciduous seedlings the branches or the stems are bent under the weight of the hyraxes until they break near their base (Figure 6). Planting has had to be stopped until the hyrax problem could be solved (S. Moran, unpublished data).

Fluoroacetamide (FAA) is an odourless water- soluble chemical. Although it is very toxic to most mammals (e.g. the LDs0 to Rattus norvegicus is

13 mg/kg (Bentley and Greaves, 1960) and 0.58 mg/kg to Meriones tristrami (Braverman, 1968), it causes no secondary poisoning of predators (Wolf, 1966), and is therefore used for control of field rodents in Israel (Wolf, 1977). It is less toxic to birds (Wolf, 1966).

The lethal dose of FAA in the rock hyrax was found in preliminary tests to be 0.9 mg/kg (S. Moran, unpub- lished data). This means that the lethal dose for an adult hydrax, weighing 3-4 kg (Maeltzer and Livneh, 1982), is about 3mg a.i. FAA.

In preliminary tests with baits of sorghum grains, alfalfa, apple leaves, chicken feed pellets, flour and apples, apple chips were found to be the only attractive bait to the rock hyrax (S. Sorer, unpublished data).

Preliminary trials in rock hyrax control were con- ducted in the winter of 1981/82, using apple bait containing 0.01-0.02% FAA. In three out of four test plots no damage was recorded during the next spring and summer (Moran et aL, 1983).

The experimental control operation described here was conducted in Western Galilee in June-August 1982.

Materials and methods

The 12 plots tested were located in the mountains of Western Galilee (Figure 7) in seven plantations, located at Elon, Avdon, Goren and Ya'ara (Table 1), in an area of 8 x 3 km (Figure 8).

As each plot tested was populated by a family of rock hyraxes that moved freely along the terraces, it was impossible to divide it into control and treated plots: therefore, synchronous damage evaluation served as a control for the post-treatment data (see Table 3).

Regular observations on the size of the hyrax

0261-2194/87/04/0265-06 $03.00 © 1987 Butterworth & Co (Publishers) Ltd

Page 2: Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits

266 Control of rock hyrax in orchards

TABLE l. Description of test plots

Test area Age of trees Neighbourhood Plot no. Plantation Crop (ha) (years) vegetation Remarks

1 Elon A Apple 3 Adult Apple gardens 2 Elon B Peach 2 Adult Peach orchard 3 Avdon A Avocado 1.5 2 Avocado gardens

and natural thicket 4 Avdon B Avocado 0" 8 1 Natural thicket 5 Goren A Avocado 5 1 Natural thicket 6a-c Goren B Peach 5 1 Natural thicket

7a-d Ya'ara Avocado 12 Seedlings Natural thicket

Damaged for several years Damaged for several years Avocado plot of 0-1 ha out of the long narrow plantation

Many terraces divide the orchard into several plots. Control was operated in the whole area. Damage and bait assessments took place in the three most damaged plots (6a-6c) Soil preparation and planting continued during the research. Control was operated only in four relatively small plots where hyrax damage was found

FIGURE 1. A 1- to 2-year-old female rock hyrax. FIGURE 3. Fruit-bearing apple tree severely damaged by a family of rock hyraxes.

FIGURE 2. A terrace made of uprooted rocks along the border of a 3-year- old avocado orchard in Avdon. The natural thicket can be seen behind the terrace.

families could not be performed, but the population was roughly estimated by visual sighting of the animals and findings of fresh droppings. Trapping success was too poor to estimate the population size in this way. It was impossible to rely on the number of carcasses found after poisoning because the sick animals tend to hide away (S. Moran, unpublished data), and cannot be

C R O P P R O T E C T I O N Vol 6. A u g u s t 1987

traced. The hyrax population was therefore estimated by two indices: (a) untreated bait consumption before and after the control operation, and (b) the amount of tree damage before and after the control operation.

Fresh sliced apples were used as untreated bait. The treated bait was prepared by soaking apple slices in a 0" 4°7o aqueous solution of FAA for 5 minutes. The final concentration was found to be 0.04% by weight. A weighed amount (500 or 560g) of bait was put in white plastic plates (22cm diameter), which were placed in the bait stations on wide flat stones of the terraces. The number of stations per plot was determined for each plot according to the terrace length and the distribution of the signs of hyrax activity (damaged trees nearby, droppings, hyrax runs in the vegetation and visual spotting of the animals), and was kept constant during the whole length of the experiment (Table 2). The number of bait stations was limited, although the hyrax population had the ability to consume more bait in some cases: this was done to force the animals to use a limited number of treated bait stations. On the other hand, several stations were put on each terrace (except in plot 7b) to prevent the dominant members of the rock hyrax

Page 3: Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits

S. MORAN, S. SOFER AND M. COHEN 267

FIGURE 4. Damage to foliage by rock hyraxes in a 3-year-old avocado tree. FIGURE 6. One-year-old peach tree in which three of the four branches have broken under the weight of browsing rock hyraxes.

km I- . . . . " ' " " " i "';I

A ' riyya N'~ / H A G A L I L ( G A L I L E E )

Zefat • !J

;I

:EE~E::

i!~i!~ii!iii Haifa Tiberias

Nazareth • I

I /" If,'"

FIGURE 7. Map of Galilee, with the experimental area marked by a rectangle.

FIGURE 5. Avocado seedling severely damaged by rock hyraxes.

family having control over all o f the bait in the plot. T h e total bait amount was va r i ed in order to test the sufficiency o f the amounts o f the bait in the whole plot (Table 2). T h e stations were inspected daily, and the percentage o f bait consumpt ion was evaluated and eaten or dried-up bait was replaced by fresh bait daily.

After pre-bait ing for different periods (Table 2), the

CROP PROTECTION Vol. 6 August 1987

Page 4: Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits

2 6 8 Control of rock hyrax in orchards

TABLE 2. Bait consumption by rock byraxes

Pre-baiting* * Treated bait consumption (kg)

Average bait

Total consump- Period between No. of bait tion per Estimated control operation

Plot baiting weight Duration day no. of and post-baiting no. * stations (kg) (days) (kg_+SD) animalst Day 1 Day 2 Total (days)

Post-baiting* *

Time from

start of control

measures to

Average complete bait cessation

consump- of bait tion per Estimatedconsump-

Duration day no. of tion (days) (kg_+SD) animals'r (days)

4rep.§ 20 11.2 4 7-0 _+ 1.3 28 2.88 3.70 6.58 No post-baiting 6b+c 19 10-0 5 4 .3 _+ 1.6 26 1.74 0 1.74 1

3 15 8.4 8 4.3_+2-5 30 1-12 0.62 1.74 2 6a 13 7.3 5 3 .3_+0.7 16 0.53 0 0.53 7

4 10 5.6 8 3.5_+1.4 21 2-18 0 2"18 2 5 10 5"6 9 3"9 -+ 0"9 19 1-54 ?# ? No post-baiting 1 9 5.4 4 3.3 _+ 1.5 20 4.32 0.27 4.59 No post-baiting 2 6 3.6 3 3.5_+0.1 >14 1.14 2-28 3.42 4 7a 6 3.4 5:1: 0 . 4 - + 0 . 4 > 4

8# 3.0 _+ 0.3 >13 2.08 3.02 5.10 No post-baiting 7d 5 2.8 7 2 .5_+0.3 >11 0 0.34 0.34 No post-baiting 7c 3 1.7 7 1.6_+0.2 > 7 0 0.73 0.73 No post-baiting 7b 1 0.6 13 0.5_+0.1 > 2 0.06 0.20 0.26 No post-baiting

6:1= 2 .0_+0.7 12 5# <0 .1 1 16 4 0 .3_+0.6 5 6 5# 1.5_+0.3 7 6# <0-1 1 15 4 0.2__.0.5 4 6

5 0 .6_+0.2 4

* As in Table 1. * * Untreated apple slices (560-600g per bait station). "I" Calculated by dividing the highest daily bait consumption on the terrace by the average daily bait consumption in the laboratory. :[: Data were split into two stages, according to the difference in the intensity of bait consumption. § Damage reappeared in plot 4 a month after the end of the control, and necessitated a repeated control operation. -~ Bait was removed by a Nature Conservancy official.

[::~' S h e I o m ~ _ . . . . - ~ ' - " - ~ ' - ~ ~ _~, .~ . . . . " --~" L; )

:~:i-!;:~i~ ~k .:::::::i :: !i~t,. Goren B

I ) ~-~ ,, . . . . ,, ( ~ Goren

~ k . . . _ . ~ ~ ; - ! : : : : ' , ! i A v d o n Y a a r a . ' ( -

FIGURE 8. The experimental area. * test plots; . . . . streams (mostly dry in summer when this study took place); - - roads; shading= built-up areas.

bait was replaced by a poisoned bait, in amounts equal to that of the pre-bait. It was offered for 48h, without adding or changing the bait, although consumption was evaluated daily, as described above. At the end of this period the remains of the treated bait were removed. In five cases (Table 2) the treated bait was then replaced by an untreated one, for post-baiting conducted in the same manner as the pre-baiting census.

In avocado seedlings and 2- to 3-year-old avocado trees (Figure 5) the percentage of foliage consumed in each tree by rock hyraxes between two observation dates was estimated separately: the results were pooled for final analysis. In deciduous seedlings, damage was assessed as in the avocado trees and, in addition, the number of broken branches in every tree was counted. As the research was conducted in June-August, the leaves did not grow significantly nor did the trees defoliate naturally.

C R O P P R O T E C T I O N Wol. 6 Augus t 1987

Damage mostly occurred in only part of the plot, chiefly in the first row of trees adjacent to the hyrax dens in the terrace. Sometimes, especially in seedlings, plants in the second and third rows (plots 7a-d) were also damaged. The damage was estimated, therefore, in these damaged trees only.

In adult apple, Pyrus malus L., and pear, P. communis L., trees, which had been browsed by the hyrax for several years, it was impossible to assess the damage during the pre-baiting period. On the other hand, it was possible to distinguish whether the damage had stopped or was continuing after the control operation (plots 1 and 2, see below) (Figure 3).

The Western Galilee landscape is widely covered by natural thicket, mainly Quercus calliprinos Webb and Pistacia palaestina Boiss. (Waisel, Pollack and Cohen, 1978). The experimental plots were situated amid natural thickets (Table 1). Plots 1, 2 and 3 were located in fruit-garden complexes, which were sur- rounded by such thickets. Only plots no. 1 (Elon A) and 6a-c (in Goren B) were located close to a built-up area (Elon) (Figure 8).

Resul t s

The bait consumption on the terraces is summarized in Table 2. The untreated pre-bait was well accepted by the rock hyraxes. Only in plot 7a did bait consumption begin on the third day, whereas in the 11 other plots consumption began on the first day. Consumption continued without a pause until the bait was replaced

Page 5: Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits

S. MORAN, S. SOFER AND M . COHEN

with the treated one. The pre-bait duration was 3-13 days (average 7.6 days). The differences in length of the pre-bait period did not affect the amount of the treated bait accepted. The 1- to 2-day delay between the pre-bait and the treated bait stages had no effect on the treated bait acceptance, compared with those experiments in which there was no such delay.

In Table 2 the tests are listed according to the total bait offered and also the number of baiting stations per terrace. The rock hyraxes consumed all the bait offered where it was 3.6 kg or less, and which was distributed in six or fewer bait stations. When the amount of bait offered was greater than 3.6kg, only part was con- sumed, with daily consumption of 3 .3 -7 .0 kg; thus, in some of the plots, the hyraxes were able to consume greater amounts of bait, if it was offered to them. Therefore, in this case, the number ofhyrax specimens per plot was probably greater than the number

8

8 .~_ 0

._>

C3

i i i i i

-8 -6 -4 -2 0 0 t I

Days b e f o r e 4 8 h c o n t r o l c o n t r o l

o p e r a t i o n o p e r a t i o n I I

i i i

2 4 6

z~ ~ z~ A z~ ~ z~ A z~ z~ z~

8 10 12 14 16 18

Days a f t e r c o n t r o l o p e r a t i o n

FIGURE 9. Bait c o n s u m p t i o n in plot 6a in the G o r e n peach o rchard , h To ta l a m o u n t o f un t r ea t ed bai t available in plot; • total a m o u n t o f t rea ted bai t available; O total a m o u n t o f un t r ea t ed bai t c o n s u m e d b y hyraxes; • total a m o u n t o f t rea ted bai t c o n s u m e d b y hyraxes.

269

calculated from bait consumption. The estimate in the plots with more than nine bait stations was 16-30 animals, with the amount consumed being fairly high in most cases. In three cases (plots la, 7b, 7c) there was a build-up of the daily amount ofpre-bait consumption during the first 1-2 days; in plot 7a the duration of this build-up was 5 days.

In three cases (Table 2, plots 6b + c, 6a, and 4), all the treated bait was consumed on the first day and none on the second day (see Figure 9); in two cases (plots 3 and 1) the amount eaten on the first day was greater than that on the second day, and in four cases (plots 4rep., 2, 7a and 7b) the reverse was the case; finally, in two cases (plots 7d and 7c) the treated bait was con- sumed on the second day only. In one case (plot 5) the only information available is that the bait was eaten on the first day, but its fate on the second day is unknown.

Post-baiting consumption was assessed in five plots only. There was a significant reduction in bait consumption between pre-baiting and post-baiting (Figure 9). Post-baiting consumption in these five plots continued for 6-16 days, until it stopped entirely.

Damage (Table 3) was not assessed in plots 1 and 2 (Elon A and B). In all ten other plots damage stopped after the control operation had been completed. In seven plots damage stopped entirely and immediately. In plot 6a, located at Goren B, four damaged trees (2.6% of the 151 trees inspected) were found on the 42nd day after the control operation, but during the next 2 months no new damage was recorded. In plot 3 (Avdon A), one tree with negligible damage was found 118 days after the control operation. The only serious recurrence of rock hyrax damage occurred in plot 4

TABLE 3. Damage assessment in fruit trees during rock hyrax control operation

No. of Plot trees no. * inspected

Average percentage of Percentage of trees Average no. of Days of inspection Percentageoffreshly foliage damaged per with freshly broken broken branches per

after: damaged trees tree (_+ SE) branches# tree (_+ SE)~

Previous inspection End of Pre- Post- Pre- Post- Pre- Post- Pre- Post- No. of control

of trees treatment treatment treatment treatment treatment treatment treatment treatment treatment (check) plots=

4rep.** 103 16 69 17.5 0 23-4_+4.8 0 6b 10 110 8 0 . 0 t 0 18 .8_+3.4 t 0 4 0 . 0 t 0 3 .0_+1.5t 0 4rep., 7b,7c, 7d 6c 19 110 63 .2 t 0 9.1 _+2.9"]" 0 57 .9 t 0 2 .0_+0.9t 0 4rep., 7b,7c, 7d 3g 101 3 4 . 7 t 16-5_+4.4t

6 50 18.8 0 12-9_+3.1 0 4rep., 5,7b, 7c, 7d 6a§ 151 42 53 .6 t 0-7 16 .3_+4.2 t 2 2 8 . 5 t 2 .0 1.8-+ 1 .0 t 1.3_+0.8

68 0 0 0 0 4rep., 7b, 7c, 7d 4g 103 4 8 . 5 t 49.2 _+ 6 . 0 t

12 30 66.0 0 47.8_+6.3 0 5, 7b, 7c, 7d 5§ 18 3 8 . 9 t 45.7 _+ 6 . 7 t

7 88 44.4 0 61.5_+6.7 0 4rep. 7a§ 56 2 5 . 0 t 92.1 _+ 4 . 0 t

8 100 23.2 0 62.3_+6-6 0 4rep., 5,7b, 7c, 7d 7d 8 85 8 7 . 5 t 0 53 .6_+6-3t 0 4rep. 7c 9 85 6 6 . 9 t 0 70 .4_+6-0t 0 4rep. 7bg 25 68" 0 t 55" 9 _+ 6" 3t

8 95 20-0 0 38.0_+6-0 0 4rep.

* The numbers refer to the plantations listed in Table I. Damage was not evaluated in plots 1 and 2. * * Damage recurred in plot 4 a month after the end of the control measures and necessitated a repeat of the control operation. t Cumulative damage from the beginning of the season. =[= This phenomenon occurs only in deciduous trees. S Two succe~ive assessments took place before and/or after the control operation. # Serial numbers of other plots, in which damage to trees was assessed at the same time that control measures were in operation in the test plot in question. These plots serve,

therefore, as control (check) plots.

C R O P P R O T E C T I O N Vol 6. August 1987

Page 6: Control of the rock hyrax, Procavia capensis, in fruit orchards by fluoroacetamide baits

270

(Avdon B), approximately one month after the control operation, and was more severe than the previous damage, involving 36% more trees. The control operation in this plot (plot 4 rep. in Tables 2 and 3) was repeated, and hyrax activity subsequently ceased.

Damage was assessed in tested plots (apart from 4rep.) during the post-baiting period by comparison with pre-baiting assessments.

After the termination of the control operation, the terraces and their surroundings were searched for rock hyrax carcasses, and a smell of decay was noted. Rock hyrax carcasses were found in two plots only: 16 (8 adults and 8 cubs) in plot 1 (Elon A) and two adults in plot 4 (Avdon B). All the carcasses were found in crevices of the terraces. In all cases the smell of decomposing carcasses persisted for several days after the treated bait was removed. The farmers noticed that they no longer encountered rock hyrax families upon entering their plots, in sharp contrast to the situation before steps had been taken to control these animals.

Test plots subsequently were kept under regular surveillance. There was no more damage to the trees during the remainder of 1982 or during 1983 and 1984. During 1983, rock hyraxes were seen on only two occasions in the four villages treated in 1982: both incidents were in new plots, one in another part of the Elon A fruit orchard and the second in another plot at Avdon. During these years, rock hyrax damage to fruit trees occurred in other villages in Galilee.

Control of rock hyrax in orchards

animals had probably been unable to penetrate any further between the rocks.

In all cases the total amount of treated bait consumed within 48h was less than that expected according to the pre-baiting data. This was probably the result of poison aversion, a phenomenon also observed in the laboratory (S. Moran, unpublished observations).

The use of an acute and non-specific poison can, in theory, be dangerous to wildlife by direct intoxication. During this study, bait stations were in exposed situations on the rocks, in order to facilitate the assess- ment of bait consumption. Despite this, no carcass of any other fruit-eating animal species was found in the vicinity of the treated area. Nevertheless, future control measures must use treated bait which is placed deep within the rock crevices to prevent its con- sumption by non-target animals. According to toxico- logical data there is no danger of secondary poisoning of predators feeding on dying poisoned animals or on carcasses. Furthermore, the death of the poisoned rock hyraxes inside the crevices reduces the risk of secondary poisoning.

Acknowledgements

The authors thank the farmers who assisted in the work in their plots. The study was financed by the Galilee District of the Jewish Agency.

Discussion

Control of rock hyraxes with fluoroacetamide (FAA) baits stopped fruit tree damage in all treated plots, for at least 21/2 years. During this period, planting activity in the test plots continued without loss of seedlings, and the older trees recovered from their previous damage.

Extreme changes in the size of rock hyrax popula- tions have not been documented, apart from a high mortality resulting from extremely cold and rainy weather in Galilee (Maeltzer, 1973). During the period of our successful operation to control rock hyraxes, damage attributable to these animals continued to be reported from the adjacent villages ofZar ' i t , Shomera and Shetula. Thus the sole explanation of the decline in the hyrax population during the summer months in Galilee must be the control measures taken.

A pre-baiting period of about 3-5 days is necessary, as in some cases it took a few days for bait consumption to build up.

Dead hyraxes were found in only two instances, with the carcasses deep inside the crevices between the stones. S. Moran (unpublished data) previously observed in the laboratory that rock hyraxes that have consumed FAA search for a shelter as soon as the first symptoms of poisoning appear. The same phe- nomenon occurred in the field, where the poisoned hyraxes hid themselves deep within the crevices. In the two instances in which carcasses were found, the dying

CROP PROTECTION Vol. 6 August 1987

References

BENTLEY, E. W. AND GREAVES, J. H. (1960). Some properties of fluoroacetamide as a rodenticide. Journal of Hygiene 58, 125-132.

BRAVERMAN, Y. (1968). The toxicity of fluoroacetamide for jirds (Meriones tristrami). Refuah Veterinarith 25, 166-171.

MAELTZER, A. (1973). Heat Balance and Water Economy of the Rock Hyrax (Procavia capensis syriaca Schreber 1784). PhD thesis, Tel-Aviv University, Tel-Aviv, Israel (in Hebrew with English summary).

MAELTZER, A. AND LtVNEH, M. (1982). The Rock Hyrax. Ramat Gan, Israel: Massada (in Hebrew).

MORAN, S., SOFER~ S. AND COHEN, M. (1983). Preliminary trials to control Procavia capensis in fruit orchards by fluoro- acetamide. Phytoparasitica 11, 60-61 (abstract).

WAISEL, Y., POLLAK, G. AND COHEN, Y. (1978). The Ecology of Vegetation of Israel. Petah-Tiqwa, Israel: Division of Ecology (in Hebrew).

WOLF, Y. L. (1966). Control of field rodents. In: Seminar on Rodents and Rodent Ectoparasites, Geneva, 24-28 October 1966. WHO/Vector Control/66.217, pp. 107-111. Geneva: WHO.

WOLF, Y. (1977). The levant vole, Microtus guentheri (Danford et Alston, 1882). Economic importance and control. EPPO Bulletin 7, 277-281.

Received 20 January 1986 Revised ll December 1986 Accepted 22 January 1987