Intrinsic individual variation in daily activity onset and plastic responses on temporal but not spatial scales in female great tits

Abstract

In a variety of species, individuals appear to be consistent in the daily timing of their activity onset. Such consistent among-individual differences can result from both intrinsic factors, as individuals may e.g. differ genetically, and extrinsic factors, as the environment may vary on spatial and temporal scales. However, previous studies typically did not differentiate between their respective contributions on individual variation in the timing of activities. Here, we repeatedly measured the onset of activity in female great tits (Parus major) on consecutive days during the egg laying phase of the breeding season in four consecutive years. Subsequently, we used a variance partitioning analysis in order to determine which part of the total variation could be attributed to intrinsic (female identity) and extrinsic (nest box identity) factors. Overall, 27% of the total variation could be attributed to female identity. In addition, we found temporal variation in the activity onset, indicating that individuals can plastically adjust their timing. Yet despite their general ability to change the timing of activities over time, spatial environmental factors did not contribute significantly to the observed variation. Individuals may choose a habitat that matches the preferred timing of activities, or might not benefit from adjusting their timing to environmental factors that might vary on spatial scales.

No relationship between chronotype and timing of breeding when variation in daily activity patterns across the breeding season is taken into account

“…As timing of activity is thought to be consistent we expected that individuals with relatively early timing during the egg laying phase would also be early during the pre-egg laying phase. We showed that emergence time is repeatable on the long term (i.e., across years) in female great tits in our population (Meijdam et al, 2022). Therefore, we decided to measure emergence and entry times mainly during the egg laying phase.…”

Short‐time exposure to light at night affects incubation patterns and correlates with subsequent body weight in great tits (Parus major)

“…In particular, they delay their activity onset and advance their offset throughout incubation, while responses to environmental factors, such as temperature and rain fall, additionally increase variation between days. This large plasticity in females is also reflected in their repeatability of onsets ranging from 0.13 to 0.46 and offsets from 0.00 to 0.37 (Meijdam et al, 2022; Schlicht & Kempenaers, 2020; Stuber et al, 2015). It is important to experimentally disentangle daily effects from those of ALAN by looking at between‐ as well as within‐individual responses.…”