Multi-dimensional niche differentiation of two sympatric breeding secondary cave-nesting birds in Northeast China using DNA metabarcoding

Niche theory predicts that ecologically similar sympatric species should show differentiation in at least one of the main niche dimensions (time, space, and/or food). Here, we combined observations of breeding timing, nest site selection, and diet (the latter determined using DNA metabarcoding) to analyze the niche overlap and differentiation between two sympatric secondary cavity-nesting birds, the Japanese Tit Parus minor and the Yellow-rumped Flycatcher Ficedula zanthopygia. The results showed that 1) there were significant differences in the first egg laying date, length of the egg laying period, incubation date, and hatching date between tits and flycatchers, and the breeding time of flycatchers peaked later (about 30 days) than that of tits; 2) the two species had a large overlap in nest site selection, although the canopy coverage and shrub density of flycatchers were significantly higher than those of tits; and 3) the niche overlap in diet was minimal, with both species heavily ..., Study area
The study was conducted during two breeding seasons (2021–2022) in Zuojia Nature Reserve, Jilin, northeastern China (44°1ʹ–45°0ʹN, 126°0ʹ–126°8ʹE). The reserve has an area of 60 km². The altitude is 200–554.6 m, with a continental monsoon climate in the temperate zone. The average annual precipitation is 680 mm, and the average temperature is 5–6°C. The vegetation is a natural secondary broad-leaved forest (Deng et al., 2011), including Betula dahurica, Fraxinus mandschurica, Quercus mongolicus, and Tilia mandshurica. Artificial nesting boxes (12 cm × 12 cm × 25 cm inside, 4.5 cm diameter of the hole) were hung in the study area to attract the tits and flycatchers. The nesting boxes were randomly attached to trees at a height of about 2.5–3 m above the ground, with a minimum distance of 30 m between each box. The tree species and nesting orientation were assigned at random, and the number of nesting boxes was maintained at about 450 year round (Yu et al., 2017).
Data collecti..., , # Multi-dimensional niche differentiation of two sympatric breeding secondary cave-nesting birds in Northeast China using DNA metabarcoding

[https://doi.org/10.5061/dryad.dbrv15f8g](https://doi.org/10.5061/dryad.dbrv15f8g)

We combined observations of breeding time, nest site, and diet to analyze the niche overlap and differentiation between two sympatric secondary cavity-nesting birds, the Japanese Tit *Parus minor* and the Yellow-rumped Flycatcher *Ficedula zanthopygia*. The results showed that 1) there were significant differences in the first egg laying date, length of the egg laying period, incubation date, and hatching date between tits and flycatchers, and the breeding time of flycatchers peaked later (about 30 days) than that of tits; 2) the two species had a large overlap in nest site factors, but the canopy coverage and shrub density of flycatchers were significantly higher than those of tits; 3) the two species had a large overlap in diet, and both largely relied on Lepidopt...,