Birds are commonly used as bio-indicators of the quality of environments and the changes to them. Therefore, ecologists put a lot of effort into the monitoring of their population trends. One of the methods used for bird population monitoring is autonomous sound recording. Current studies provide inconsistent results when the number of detected species by autonomous sound recorders was compared with that delivered by an observer. In our study, observers counted birds using a point-count method at 64 random points in forest and farmland. At the same points, autonomous sound recorders recorded the soundscape four separate times (including counting by observer period) and the species present in the recordings were later identified by observers in the lab. We compared the number of species detected by simultaneous observations and recordings, as well as the number of species detected by recorders during four different surveys. Additionally, we calculated the Sorensen index to compare the species composition during different surveys at the same point. We found that observers detected more species than autonomous sound recorders. However, differences in the number of detected species were habitat dependent–observers detected more species than recorders in farmland, but not in the forest. When the time for recording was doubled, recorders were more effective than observers during a single survey. The average Sorensen index between the four repeated surveys performed by autonomous sound recorders ranged from 0.58 to 0.67, however we did not find significant differences in the number of species detected during different surveys conducted at the same point. Our study showed that 10-minutes sampling from the same point gives various species composition estimates but not species richness estimates between different surveys. Therefore, even when recorders detect less species than observers during the simultaneous surveys, increasing the survey duration of recorders may alter this difference. The use of autonomous sound recording for monitoring bird populations should be promoted, especially in forest habitats, as this technique is easier to standardise, eliminates many errors observed in the traditional point-count approach, enables conducting survey during adverse field conditions and delivers more reliable results for the majority of the species.
Most bird species sing by day, with two distinct peaks of vocal activity—around sunrise and sunset. However, even typically diurnal birds also sing during at night what is for them an atypical part of the day. To date, the mechanism and function(s) of such behaviour remain unclear across bird taxa. In our study we focused on night singing by diurnal birds in two different types of environments—forests and open areas in eastern Poland. We examined: (1) which diurnal species sing at night (defined as the period between astronomical dusk and dawn); (2) how intensively different species vocalise at night; and (3) whether the occurrence of nocturnal singing by diurnal birds depends on the type of environment. To do this, we used autonomous sound recorders to record soundscapes in 27 points located in open habitats and 27 points located in forests. At each location the recorder continuously collected data for an entire day during the breeding season, from one hour before dawn to 10 AM the next day. All night songs were classified to their species of origin via manual spectrogram scanning. We recorded 88 bird species in total (12 orders, 32 families), of which 24 species (7 orders, 15 families) sang at night. Night singing was observed significantly more often in open areas than in forests. The frequency and intensity of night singing was species-specific and ranged from occasional singing to regular and intense singing. We hypothesise that elevated light levels have a crucial influence on night singing, but that the effect of light may also be modified by environmental factors (e.g., predator pressure).
The point-count method is one of the most popular techniques for surveying birds. However, the accuracy and precision of this method may vary across various environments and geographical regions. We conducted sound-recorder-based point-counts to examine the accuracy and precision of the method for bird biodiversity estimation as a function of geographical region, habitat type and the time of day at which the survey began. In temperate (Poland) and tropical (Cameroon) regions, we recorded soundscapes on two successive mornings at 36 recording sites (18 in each location). At each site, we analyzed three 5-min surveys per day. We found no differences in the accuracy and precision of the method between regions and habitats. The accuracy was significantly greater at sunrise than during later surveys. The similarity of the bird assemblages detected by different surveys did not differ between regions or habitats. However, the bird communities described at the same time of day were significantly more similar to each other than those detected by surveys conducted at different times. The point-count method provided statistically indistinguishable estimates of bird biodiversity in different geographical regions and habitats. However, our results highlight two weaknesses of the method: low accuracy (41–54%), which limits the usefulness of a single survey in understanding bird–environment relationships, and changes in accuracy throughout the day, which may result in the misinterpretation of the status of bird populations.
Wprowadzenie i cel. Glony z rodzaju Prototheca to bardzo interesujące i wyjątkowe mikroorganizmy należące do królestwa roślin (Regnum Vegetabile), które są w stanie zakazić zwierzęta i ludzi, powodując choroby zwane prototekozami. Przez długi czas glony z rodzaju Prototheca nie były uznawane za patogeny groźne dla ludzi. Ewentualne izolacje tych mikroorganizmów z ran, krwi czy kału zazwyczaj interpretowano jako saprofity bądź też zanieczyszczenia. Celem pracy jest zaprezentowanie dotychczasowego stanu wiedzy dotyczącego biologii, identyfikacji oraz chorobotwórczości dla ludzi i zwierząt bezchlorofilowych glonów z rodzaju Prototheca. Opis stanu wiedzy. Prototekozy to dość nielicznie spotykane infekcje, wywoływane przez bezchorofilowe glony z rodzaju Prototheca, które są szeroko rozpowszechnione w środowisku. Glony te są patogenami dla zwierząt i człowieka. Prototheca spp. mogą powodować infekcje u ludzi, ale stanowią także problem w przypadku zakażeń zwierząt (przede wszystkim gdy wywołują zapalenie wymienia u krów mlecznych), przynosząc znaczące straty ekonomiczne. Budowa glonów z rodzaju Prototheca powoduje, że są one oporne na większość fungistatyków, antybiotyków, środków dezynfekcyjnych, a także cechują się opornością na wysokie temperatury. Podsumowanie. Ze względu na zdolność glonów Prototheca do zakażania organizmów zwierzęcych, jak i ludzkich oraz ich dużą oporność na wiele czynników i środków istotne jest pogłębienie wiedzy dotyczącej glonów Prototheca i lepsze poznanie tych niezwykle ciekawych mikroorganizmów, aby w przyszłości móc bardziej efektywnie leczyć prototekozy, które ze względu na zwiększającą się liczbę osób z obniżoną odpornością mogą dotyczyć coraz to więcej nie tylko zwierząt, ale także i ludzi.
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