On Monday 14 May 2018, I found a presumed hybrid Western Bonelli's x Wood Warbler at Noordhollands Duinreservaat, Castricum, the Netherlands. On 29 May, the bird was still present and, to my surprise, it was no longer alone. Obviously, a female Wood Warbler had fallen for the striking looks and accent of the devoted singer. What's more, she was building a nest and he followed her everywhere she went!
In the weeks that followed, Hans Schekkerman and I regularly visited the birds, gathering information on their breeding behaviour. The female laid five eggs, however, on 19 June only three young were in the nest. Presumably, two unhatched eggs had been removed. On 23 June, the young were ringed and c five days later they successfully fledged.
Depicted below are some of the photos and sound-recordings I made. Up next, I will be working on an article about this remarkable record; a DNA analysis – expected to take place later this year – will hopefully confirm the identity of the presumed hybrid.
To be continued ........
Presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix, between song phrases, 14 May 2018
Female Wood Warbler Phylloscopus sibilatrix, collecting nesting material, 29 May 2018
Presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix, watching over female while collecting nesting material, 29 May 2018
Wood Warbler Phylloscopus sibilatrix, with nesting material, 29 May 2018
Wood Warbler Phylloscopus sibilatrix, near nest, 31 May 2018
Young of presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix and Wood Warbler Phylloscopus sibilatrix, 23 June 2018
Presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix, collecting food for its young, 23 June 2018
Presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix, bringing a caterpillar to its young, 25 June 2018
Nest with three young (c 10 days old) of presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix and Wood Warbler Phylloscopus sibilatrix, 26 June 2018
Presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix, giving agitated calls with a Eurasian Jay nearby, 27 June 2018. Click here to listen to the recording.
Wood Warbler Phylloscopus sibilatrix, near nest, 28 June 2018. Click here to listen to the recording.
Begging calls of fledgling of presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix and Wood Warbler Phylloscopus sibilatrix, 29 June 2018. Click here to listen to the recording.
Fledgling of presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix and Wood Warbler Phylloscopus sibilatrix, 29 June 2018
Presumed hybrid Western Bonelli's x Wood Warbler Phylloscopus bonelli x P. sibilatrix, job done (almost), 29 June 2018