Bird Species Diversity of the Mitidja Plain (Northern Algeria) with Emphasis on the Dynamics of Invasive and Expanding Species

This treatise investigates the poorly studied bird fauna of Mitidja Plain (Northern Algeria), with particular notes on the occurrence and expansion of new and alien species. Direct observations, supported by ornithological surveys carried out by Progressive Frequential Sampling (PFS), a version of a point count method, have allowed us to identify 125 bird species. These represent 31% of all species known from Algeria. The species recorded belong to 14 orders, 39 families and 37 genera. According to their biogeographic origins, 36 are Mediterranean, 32 Palearctic, 24 Holarctic, 17 European and 16 of European-Turkestani origin. The Mitidja Plain holds 60 resident-breeder species (48% of all registered species) and is a transit zone for many migratory species (summer and winter migrants constituting 20% and 14% of the total, respectively) and occasional visitors (RA = 12%). Among recently expanding species (introduced or local), the Collared Dove Streptopelia decaocto and Wood Pigeon Columba palumbus, sampled by the spot-mapping method, experienced a very rapid population growth. The first observations of the former were made in 1996 in Algiers. Its numbers experienced a steep increase after 2002, starting from 5.75 pairs/10 ha to reach up to 31.5 pairs/10 ha in 2006. The same applies for the Rose-ringed Parakeet Psittacula krameri, surveyed by direct-count at roosting sites. This species has been able to increase and reproduce since its first introduction into the wild in 1996. The increase in study species populations, especially the Rose-ringed Parakeet, may derive from good weather conditions that favoured the species through providing better feeding conditions, thus high reproduction outcomes.