Thesis (Ph.D. (Zoology & Entomology)) - Rhodes University, 2008.

The loss of habitat to agriculture is a worldwide problem for biodiversity conservation. One species that has seemingly been able to adapt to the conversion of forests to farmlands is Mackinder’s eagle owl (Bubo capensis mackinderi), which inhabits highland areas, but little is known of its ecology, especially outside of protected areas. This study examined the impact of agricultural practices and farmer’s attitudes on the foraging and population ecology of the Mackinder’s eagle owl in central Kenya. Owl territories were monitored monthly from June 2004- October 2006 for signs of occupancy, breeding activity, mortality and to collect data on food resources. Nest site characteristics were measured for all known nests. Because previous studies showed an affinity for rodents, small mammals were trapped monthly using mark-recapture methodology. In each territory, the type and amount of farm crops were measured each month and farmers were interviewed about their knowledge and beliefs about owls. Mackinder’s eagle owls in central Kenya lived at extremely high density 0.87 owl pairs/km². This density was high compared to other populations of Mackinder’s eagle owl and to Eurasian eagle owl (Bubo bubo) populations in Europe. Breeding success was 48% over three years and this compared well with other species of eagle owl inhabiting human-disturbed areas. All nests and roosts were located in river valleys, and all successful nest sites were located on cliffs or other inaccessible rocky terrain. Nest sites were located adjacent to farms, which provided for both open hunting and an abundance of prey. Breeding activity was concentrated after the rainy seasons and this was likely linked to prey availability after the rains. Agricultural activities generally had a positive effect on rodent populations. Small mammal trapping results revealed that rodents were over 14 times more abundant in farms than in adjacent grassland habitat. This population of Mackinder’s eagle owl had a very catholic diet and consumed mostly mammalian prey species including hares, giant rats, root rats, grooved-tooth rats and small rodents. Small rodents accounted for almost half of the owls’ diet and when their numbers increased, owls responded by consuming more of them, indicating the importance of farming activities to this population of owls. Other populations of eagle owl inhabiting human-disturbed areas had diet widths positively related to levels of habitat disturbance. This result supported optimal foraging theory that more productive environments have predators with more specialized diets, while patchy environments have generalist predators. The ecology of this population of Mackinder’s eagle owls was heavily influenced by human agricultural activities, which generally had a positive effect on their population. Farming activities changed rapidly both within and between seasons as plots were small and neighbouring farmers planted various crops at different times of the year and this was enhanced by irrigation in some areas. Year-round availability of forage within farms had a positive effect on owl prey species, some of which increased relative to the type and amount of crops found in farms. However, 57% of owl injuries and mortalities that occurred were related either directly or indirectly to human activities. Cultural prejudices against owls remain the biggest threat to this population’s long-term persistence. Farmer education was shown to play a significant role in overcoming negative beliefs about owls. Because Mackinder’s eagle owls are highly adaptable to anthropomorphic landscape changes, largely due to their adaptability as food generalists, they are one of the few top predators remaining in this highly disturbed agricultural system. However, populations within agricultural areas remain especially vulnerable to negative human attitudes towards owls due to their close association with human activities.

This diploma thesis deals with an eagle owl as a model species for environmental education. The first part focuses on this species and how it was perceived in the past and the possible reasons for its pursuit. The second part focuses on the progressive return of this owl to Czech nature and legal measures to protect it. In the third part the thesis focuses on the presence of eagle owl in neighbouring countries of the Czech Republic and their latest states and legal measures. The last and practical part is focused on the perception of secondary forestry students and grammar school students on the return of selected vertebrates to Czech nature. This part focuses mainly on comparing the perception of eagle owl to other vertebrates in Czech nature.

Los estudios de biomonitorización con aves rapaces permiten evaluar el grado de contaminación ambiental y las consecuencias sobre la salud humana y ambiental. Los niveles de metales e insecticidas organoclorados en sangre de pollos de Búho real del sureste de España fueron en general bajos, siendo los niveles de plomo significativamente superiores en los individuos nacidos en una antigua zona minera. La enzima δ-ALAD es un biomarcador sensible de exposición y efecto a plomo en esta especie. El estudio de organoclorados y PBDEs en huevos no eclosionados sugiere cambios en la dieta o posibles focos de contaminación en la zona. El grosor de cáscara de huevo disminuyó conforme aumentaron las concentraciones de p,p’-DDE, alcanzando un porcentaje de disminución relacionada con declives poblacionales en aves a niveles de DDE superiores a 100 ng/g de peso de lípidos. El desarrollo de una nueva técnica permitió detectar residuos de rodenticidas en el 83% de las muestras de hígado. / Biomonitoring studies with raptor birds can be used to evaluate environmental pollution and consequencies to human and environmental health. Levels of metals and insecticides in blood of eagle owl chicks from Southeastern Spain were in general low, being lead levels significantly higher in individuals born in an ancient mining area. The enzime δ-ALAD is a sensitive biomarker of exposure and effect to lead in this species. The study of organochlorine and PBDEs in unhatched eggs suggests dietary shifts or pollutant sources. Eggshell thickness decreased with increasing p,p’-DDE, reaching a level related to population declines in birds when DDE levels exceded 100 ng/g lipid weight. The development of a new tecnique permited the detection of rodenticide residues in 83% of the liver samples.