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Reuven Yosef and Lorenzo Fornasari

Abstract

In migrant Levant Sparrowhawk (Accipiter brevipes) at Eilat, Israel, we noted that juvenile males had two different morphs – the one described to date in literature; and a second, previously undescribed morph, with femalelike barring on the chest and flanks interspersed with tear-shaped elongated spots, giving an overall female-like appearance. Here we forward the hypothesis that explain the evolutionary consequences for the female-like plumage of juvenile males as that of intra-specific sex mimicry developed to avoid intra-specific predation by the larger females.

Open access

Agnieszka Ożarowska and Reuven Yosef

A comparison of the Emlen funnel and Busse's flat cage for orientation studies

The Emlen funnel cage was introduced in 1966. Since then it has been used in numerous studies on bird orientation. In 1995, Busse proposed another technique - in the form of flat, round cylindrical cage. Busse also tested nocturnal migrants in the daytime. He, and Nowakowski and Malecka (1999), proved that birds tested in daylight and at night displayed similar distributions of their preferred directions. This study also supports their findings. Zehtindijev et al. (2003) found that results in the Emlen funnel and Busse's flat cage were coherent, despite the tests were performed in different conditions (night-day) and in different years. This study is the first one that compares results of the same individuals tested in the two types of orientation cages during the day (N = 75) and night (N = 17). Results of both methods did not differ (Watson-Williams test of mean angles, Mann-Whitney U-test of angular dispersion) both during the day and at night. Multiheading bird behaviour is common in both types of cages and seems to be a normal feature of orientation data. The only difference was found in bird activity (i.e. number of scratches during 10 minutes of testing) that was higher for Busse's flat cage in daytime tests.

Open access

Ilan Paperna, Lajos Rózsa and Reuven Yosef

Abstract

Haemosporidian blood parasites are frequent amongst passerines. Though they often do not cause detectable consequences to host health, however, their presence or absence and also their prevalence across host populations may potentially carry meaningful information about the health, stress, body condition and viability of bird individuals or populations. The study of migratory birds captured in Eilat, Israel, allowed us to evaluate the prevalence of blood parasite infections in a wide range of both migrant and resident species in spring (N = 1,950) and autumn (N = 538) of 2004 and 2005. According to blood film microscopy, Haemoproteus spp. and Leucocytozoon spp. were more prevalent in the spring than in the autumn (0.289, 0.082 vs. 0.132, 0.033, respectively), whilst Plasmodium spp. exhibited a slight opposite trend (0.034, 0.056). All other parasites (such as trypanosomes, microfilaria and haemococcidians) were rare. During the spring seasons, prevalences were significantly higher in migrant than in resident species, whilst this difference was only marginally significant in the autumn. Given that Eilat is a migration hotspot for several Palearctic passerine species, the present descriptive study may hopefully serve to set the baseline values for future long-term epidemiological monitoring.

Open access

Piotr Tryjanowski, Martin Hromada, Federico Morelli, Emma Nelson, Pavol Prokop, Luis Reino, Lajos Rozsa and Reuven Yosef

Open access

Aleksandra Łangowska, Reuven Yosef, Piotr Skórka and Piotr Tryjanowski

Abstract

Bee-eaters (Meropidae) are considered agricultural pests and their presence provokes conflicts with beekeepers and farmers who rely on the pollination services of honey bees. This problem is often deal with through the mass killing of the birds, even though the quantitative evidence on the impact of bee-eaters on honey bee colonies is scarce. The current paper reports the performance of honey bee colonies protected with mist nets from migrating flocks of European bee-eaters Merops apiaster in Israel. In the study the weight gains of bee hives surrounded by mist nets were 6.44 times higher than that of unprotected hives (26.4 kg vs. 4.1 kg). The results confirmed that bee-eaters locally pose a problem to apiaries and potentially to the crops that require pollination. Mist- netting appeared to be an effective mitigation method for alleviating conflicts between beekeepers and bee-eaters. However, the study also showed that bees were able to differentiate between their main predator and other avian species trapped in mist nets and stung only bee-eaters. Moreover, the bees were targeting the most vulnerable body parts of birds which resulted in some bird fatalities. Therefore, due to accidental mortal- ity of birds, mist-netting is recommended only on the migratory routes in cases when bee hives cannot be moved to other areas.