MALI TORES, YOAV MOTRO, UZI MOTRO and YORAM YOM-TOV

There are differing views in the literature regarding the feeding strategy of the barn owl (Tyto alba, Strigiformes). Whereas some authors conclude that the barn owl is a selective predator, selecting to prey on certain species, oth- ers maintain that it is an opportunist. We studied the diet composition of barn owls from agricultural fields in northern Israel, using pellet analysis. Over 4,000 prey items were identified, comprising a total of at least 27 species. We found that during 1997–2001 there was a significant change in the barn owl’s diet: it switched its main prey species from the Levant vole (Microtus guent theri) to two other Myomorpha species, the house mouse (Mus musculus) and Tristram’s jird (Meriones tristrami), probably as a result of changes in the field abundance of the main prey items. Hence, although our barn owls select one prey species at a certain period of time, they exhibit an opportunistic feature in their ability to easily switch between prey items in their diet.

Zohar Leader, Yoram Yom-Tov and Uzi Motro

We studied the diets of the barn owl Tyto alba and the long-eared owl Asio otus in an arid region in the northern and central Negev Desert, Israel. The diet of the two owl species consisted mainly of small mammals, but the long-eared owl consumed a significantly larger proportion of birds in all seasons than did the barn owl. Seasonal differences in the proportion of birds in the diet of the long-eared owl were mainly due to the consumption of migratory birds. Diet composition of each of the two species resembled more the diet of its conspecifics from other locations in that region and other seasons rather than that of the other species from the same location or season. This indicates that these two owl species do not consume prey in proportion to its availability, but prefer certain types of prey over others.

Tamar Ron, S. Peter Henzi and Uzi Motro

Abstract

In this study troop of chacma baboons (Papio cynocephalus ursinus) at Mkuzi Game Reserve, Zululand, South-Africa, it is suggested that risk of predation and competition over safe spatial position had more importance and effect on female behaviour than did competition for food. Only 6.4% of all agonistic events were over food patches and no significant correlation was found between a female's dominance rank and proportion of time spent feeding, feeding bout length or diet composition. Parameters of reproductive success, such as inter-birth intervals and infant mortality were not correlated with female dominance rank. Female mortality, however, was related to dominance rank and all of the five females who disappeared during the study were low-ranking. Four of the five females disappeared after troop fission. There is circumstantial evidence supporting the suggestion that predation by leopards is the main cause of mortality of females at Mkuzi. High levels of female aggression were recorded, with almost no occurrences of support coalitions. Most of the aggression took place among similar ranking females, or was directed by the top ranking toward the lowest ranking females. Most of the female-to-female agonistic encounters were in a social context, and more than half were over a spatial position next to other adult troop members. Aggression among females increased after troop fission. It is suggested that the higher-ranking females may be better protected from predation, through access to more central spatial positions in the troop. Indeed, a positive correlation was found between a female's dominance rank and the time spent next to other adult troop members. It may be that avoiding food competition by keeping larger distances from others, while foraging, was translated in lower ranking females to a cost of higher predation risk.

Nili Anglister, Yoram Yom-Tov and Uzi Motro

The Mediterranean coastal dune habitat of Israel is diminishing rapidly, mostly due to massive urbanization, changes in habitat characteristics caused by dune stabilization and the presence of Acacia saligna, an invasive species brought to Israel for the purpose of dune stabilization. In this study we document the effect of sand stabilization on the composition of small mammal communities in the Ashdod-Nizzanim sands, Israel. We analyzed differences in species diversity and abundance for species of rodents in four types of habitat: unstable (mobile) sand dune, semi-stabilized dune, inter-dune depression and a plot of the invasive Acacia saligna. Rodent communities were found to undergo gradual changes concurrently with the stabilization of the sands. The mobile dune was the only habitat in which the strict psammophiles Jaculus jaculus and Gerbillus pyramidum were captured in abundance. No species commensal with human were captured neither in the mobile nor in the semi-stabilized dunes. However, in the inter-dune depression there was quite a large representation of Mus musculus, a rodent commensal with humans. The Acacia saligna plot had the lowest number of captures and the lowest rodent biomass calculated, with Mus musculus composing nearly half of the captures. The results of this study demonstrate that stabilization of the sands in Ashdod-Nizzanim area is associated with the disappearance of psammophile rodents and the appearance of species commensal with humans. In order to preserve the habitat for psammophile rodents, measures should be taken to halt the spread of acacia and the continuing stabilization of the sands.

Adiv Gal, David Saltz and Uzi Motro

The effect of food supplement to Lesser Kestrel (Falco naumanni) nests during the nestling period (from hatching to fledging) was studied in two nesting colonies in Israel – Alona and Jerusalem. Our hypothesis, based on diminishing returns considerations, was that food supplement will have a greater effect on fledgling success in the food-limited, urban colony of Jerusalem, than in the rural colony of Alona. Indeed, food supplement had a significantly positive effect on breeding success in both colonies. However, and contrary to our prediction, the decrease in chick mortality between supplemented and control nests in Jerusalem was not larger than in Alona (actually it was numerically smaller, albeit not significantly so). This implies either that additional factors, possibly urbanization associated, other than food limitation, might be responsible for the difference in nesting success of Lesser Kestrels between Alona and Jerusalem, and/or that the amount or the nutritional quality of the additional food provided to supplemented nests (three mice per chick per week), was not enough.

Tamar Keasar, Yonatan Bilu, Uzi Motro and Avi Shmida

Laboratory-reared bumblebees were allowed to forage on 30 artificial flowers which were identical in morphology and reward schedule, but were marked by either a human-blue, a human-green, or a human-white landing surface. The probability of nectar rewards in the artificial flowers, and their spatial distribution, were manipulated experimentally. The bees' color choices in the different experimental treatments were compared.

The proportions of visits to the three colors deviated significantly from the expected random choice (1/3,1/3,1/3) for more than 50% of the bees. Of these bees, 38%, 32%, and 30% formed a preference for human-blue, human-green, and human-white, respectively. The frequency of nonrandom color choice, and the strength of the deviation from random choice, were highest when the different colors were placed in separate clusters, lower when they were placed in adjacent clusters, and lowest when they were randomly intermingled. Nonrandom color choice was also more pronounced when the bees were rewarded according to a constant schedule, rather than probabilistically. A statistically significant preference for human-blue was found during the bees' first three visits. The bees' tendency for “runs” of consecutive visits to the same flower color can partially account for their non- random color choices. Effects of innate preferences, early learning, generalization, and search-image formation on color choice are discussed.

Royi Zidon, Hagar Leschner, Uzi Motro and David Saltz

Reintroduction of herbivores may play a vital role in restoring ecosystem functions. Here we describe the role of the Persian fallow deer (Dama mesopotamica), reintroduced into Israel, as a vector of seed dispersal by endozoochory. Persian fallow deer have a wide diet both from grazing and browsing. From fecal samples, we found that more than 30 species of plants germinated from the deer pellets. Four of the more common species are considered as ruderal. Of the trees, carob (Ceratonia siliqua) seeds were the only intact seeds found in the fecal samples. We found that ingestion by the deer has a positive effect on expediting the germination of carob seeds – a factor of ecological importance in the reintroduction environment, as it contributes to plant genetic diversity by long-range seed dispersal and to community diversity.

Myriam Freund, Ofer Bahat and Uzi Motro

We studied the use of nest-sites by Griffon Vultures (Gyps fulvus) and the breeding success in these sites during 1998–2002 in Gamla Nature Reserve (Israel). Nest-sites in which a breeding attempt succeeded in fledging a young, were more likely to be occupied by nesting vultures in the following breeding season, than nest-sites that experienced a failure. This suggests that Griffon Vultures in Gamla used a Win–Stay/Lose–Shift strategy regarding nest-site fidelity.

Edith Katsnelson Ilan, Orli Bobek, Adiv Gal, David Saltz and Uzi Motro

We studied Lesser Kestrels’ (Falco naumanni) conditional nest-site fidelity, i.e., fidelity that depends on the outcome of the previous nesting attempt in that site. In particular, we were interested in examining whether individual kestrels practice a Win–Stay/Lose–Shift (WSLS) strategy towards their nest-sites; that is, does the tendency to use the same nest-site increase following a successful nesting season, but decrease following a failure. For that purpose, we documented the use of nest-sites by Lesser Kestrels and the breeding success in these sites during 1998–2003 in the city of Jerusalem (Israel). We found that while Lesser Kestrels do not practice WSLS strategy towards their nest-site, the males (but not the females) do so towards their sub-colony – they tend to stay in the same sub-colony if their nesting was successful, whereas they tend to migrate to a different sub-colony after failure. A possible explanation to this sexual difference in WSLS behavior can arise from the fact that changing a sub-colony entails a change of hunting area. The male, being the main food provider in the Lesser Kestrel, may be more sensitive to this opportunity.