Multidimensional plasticity of phenology: Assessing the effects of population density on plastic responses of breeding time to temperature

Phenotypic plasticity is the key adaptive mechanism behind annual adjustment of breeding time in response to temperature. In nature, organisms are not only subjected to variation in temperature but encounter multiple fluctuating environmental factors that affect phenotypic expression, including conspecific density, which affects individual performances through resource competition. We examined the interactive effects of temperature and conspecific density at two spatial scales (territory and patch level) on breeding time and success utilizing data obtained from long-term monitoring of a wild great tit (Parus major) population in a fragmented woodland. As expected, we detected earlier breeding in response to warmer spring temperatures. We report earlier laying at low territory level density (i.e. a larger available area per breeding pair), but no evidence of density effects at patch level (breeding pairs per hectare). Birds experiencing low territory level density throughout their life b..., This study uses data from a long-term great and blue tit monitoring program in Belgium from 1994-2016. The “Boshoek” field site (51°08 N – 4°31 E) encompasses 12 patches of fragmented woodlands (1 to 15 ha) in an approximately 10 km2 area near Antwerp. For the purpose of this study, data from the four largest oak patches— ZZ, (11.1 ha with 96 boxes); KB, (10.1 ha with 90 boxes); LO, (6.2 ha with 62 boxes) and HN (2.8 ha with 23 boxes)—were used due to their comparable habitat characteristics (Matthysen 2002). In all sites approximately 9 boxes were available per hectare, whereby two thirds of boxes had a 32mm opening (allowing both blue and great tits) and one third had a 26mm opening (allowing blue tits only). These patches were characterised predominantly by mature stands of common oak(Quercus robur) , undergrowth of hazel (Coryllus avellana) and black cherry (Prunus serotina) , and had distinct boundaries well-defined by the sharp transition from closed-canopy forest to open areas su..., , # Multidimensional plasticity of phenology: Assessing the effects of population density on plastic responses of breeding time to temperature

Vaishnavi Purushotham, Paul Cuchot, Celine Teplitsky, and Erik Matthysen

[https://doi.org/10.5061/dryad.w9ghx3g0x](https://doi.org/10.5061/dryad.w9ghx3g0x)

## Description of the data and file structure

### Files and variables

#### File: Density\_data\_gtbtfinal.xlsx

Note: The data set has certain missing values in columns columns K, Q, S, T. These data are missing from the long term data set. The script when run on R treats these blanks as \"NA's\", and does not interfere with the results.  

**Description:** Basic phenological data of great tits and blue tits collected by conducting weekly nest box checks before egg laying. First-egg dates were estimated from the first observation of a partially laid clutch, as one egg is usually laid per day (average clutch size = 8.7). Parents were captured at the nest when the chicks were eight days old, ...