A Culture-Based Study of Micromycetes Isolated from the Urban Nests of Grey Heron (Ardea cinerea) in SW Poland

Abstract

There are many positive relationships between micromycetes and birds: They can spread fungal spores, and fungi facilitate cavity woodpecker excavation by preparing and modifying excavation sites. In turn, bird nests are mainly a source of potentially zoopathogenic fungi. The Wrocław city centre hosts the biggest grey heron breeding colony in Poland with at least 240 breeding birds pairs. To assess the possible public health risks associated with bird nests, the goal of the present study was to identify cultivable fungi present in the nests of grey herons (Ardea cinerea) in Wrocław. Additionally, attempts were made to determine whether the obtained species of fungi may pose a potential threat to animal health. Fungi were cultured at 23 and 37 ± 0.5 °C, and identified based on phenotypic and genotypic traits. Moreover, during routine inspection, visible fungal growth in some of the nests was found. Overall, 10 different fungal species were obtained in the study (Alternaria alternata, Aspergillus fumigatus, Botryotrichum piluliferum, Cladosporium cladosporioides, Epicoccum layuense, Mucor circinelloides, M.hiemalis, Penicillium atramentosum, P.coprophilum, and P.griseofulvum). They are both cosmopolitan species and a source of potential threat to humans, homoiothermous animals and plants. The greatest number of fungal species was obtained from the nest fragments with visible fungal growth incubated at 23 °C, and the least from western conifer seed bugs (Leptoglossus occidentalis) inhabiting the nests. The species such as A. fumigatus, P. coprophilum, and P.griseofulvum can be directly related to the occurrence of visible fungal growth on plant fragments of grey heron's nests.

Keywords: bird nests; fungal communities; urban area; zoopathogenic fungi.

Figure 1

Geographic location of Poland (A) and the city of Wrocław (B). Grey heron breeding colony viewed from above (C), and close-up of female individuals in the nest (D). Nests with visible fungal growth (E,F). Scale bars: A = 500 km, B = 100 km, D = 20 cm, E = 1 cm, F = 5 mm.

Figure 2

Percentage of each fungal species concerning the total isolated fungi from all studied biological materials of grey heron nests.

Figure 3

Nest fragments (A,C) after 28 days at 23 ± 0.5 °C incubation in a damp chamber and visible mycelium growth under the microscope (B). Close-up on the morphological structures produced by fungi of the genus Penicillium (D) and Aspergillus (E), which were identified by using phenotypic and molecular tests as Penicillium coprophilum, Penicillium griseofulvum, and Aspergillus fumigatus. Scale bars: B = 200 μm, D = 50 μm, E = 100 μm.