The long-staying dark morph Western Reef Heron (Egretta gularis) at Essaouira and Oued Ksob estuary (photo above) has probably hybridised with the Little Egret (E. garzetta) at the Mogador archipelago. This probable case of hybridisation was observed by Abdeljebbar Qninba and his colleagues in June 2010 and was recently published in the journal Alauda (Qninba et al. 2011).
It should be mentioned that other similar cases of hybridisation were recorded in Thyna saltpans, Tunisia (H. Dlensi in Isenmann et al. 2005), in Albufera de Valencia, Spain (Dies et al. 2001) and in the Camargue, France (Kayser et al. 2000).
Hybrids to be reported to the Moroccan Rare Birds Committee (MRBC):
Please report to the MRBC any odd-looking egret or apparent hybrid in order to gather more information about this subject. To give the reader an idea about the hybrids, I extracted the following from Dies et al. (2001) about the well-known case of hybridisation in Spain: “Apparent hybrids exhibited odd-coloured plumage, with a pale grey body and with white of variable extent on the head, wings and under-parts, even in adult plumage”.
Dies, J. I., Prosper, J. & Dies, B. 2001. Occasional breeding by Western Reef Egret in eastern Spain. British Birds 94: 382-386. PDF
Isenmann, P., Gaultier, T., El Hili, A., Azafzaf, H., Dlensi, H. & Smart, M. 2005. Oiseaux de Tunisie. Birds of Tunisia. SEOF, Paris.
Kayser, Y., Dietrich, L., Tatin, L., & Hafner, H. 2000. Nidification mixte de l’Aigrette des récifs Egretta gularis en Camargue en 1996. Ornithos 7: 37-40.
Qninba, A., Benhoussa, A., Ibn Tattou, M., El Idrissi Essougrati, A., Ben Haj, S. & Rguibi Idrissi, H. 2011. Cas probable d’hybridation Aigrette garzette Egretta garzetta x Aigrette des récifs Egretta gularis dans l’archipel d’Essaouira (Maroc). Alauda 79: 241-242. PDF
Update: hybrids recorded in Morocco:
Below are the first presumed hybrids ever recorded in Morocco (thanks to Javier Elorriaga/Tarifa Birding Tours for the photos):