Tits reproductive phenology
Study area: Reproductive phenology of tits was studied in 4 sites: in France on the Massif des Bauges and Mont Blanc, in Italy in the Mont Avic Natural Park and in the Saint-Marcel valey.
Protocol: About one hundred nests were installed at each location. These were placed on 3 transects at intervals of 50 meters at altitudes of between 800 and 2000 meters. The nests were checked every 7 days to verify the laying species and numbers of eggs laid. Nests occupation rate in the first two years was very low, almost equal to zero in populations located in Aosta Valley. In the two French sites of Bauges and Mont Blanc, the rate of occupation of the nests was 20%. The species observed were: coal tit, great tit and blue tit.
Laying dates: altitude delays the laying date on average by 10 days for every 1000 meters. The laying date was earlier by an average of 7 days in 2011 compared to 2010, with the same anticipation at all altitudes even if temperatures were much higher at high altitudes than at low altitudes in 2011, with an anticipation of 21 days at high altitude to reach the same temperatures compared to only 8 days at low altitude.
The tits reproduction dates are therefore connected with spring temperatures but these birds do not seem to completely adapt their laying date to changes in temperature. Are great tits capable of adapting by delaying reproduction depending on the climatic conditions before the laying period? If not, they will be good indicators of a possible lack of synchronization between organisms in the ecosystem coping with climate change.
The protocol is rather difficult to follow because of the need to monitor a large number of nests and thus requires an important field effort. Moreover, the rates of occupation of the nests are very low in woodlands at high altitudes.
... take a look into a coal tit nest