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Summary Tree characteristics, microhabitat, and human presence were measured around nest trees (n = 92) and non-nest trees (n = 92) to identify the best predictors of the European Turtle-dove Streptopelia turtur nest occurrence in date palm plantations of the Biskra region (Algeria). Nest occurrence was (i) positively influenced by the height of trees and that of the herbaceous layer, and (ii) quadratically affected by diameter at breast height (DBH), the cover of trees, the cover of the herbaceous vegetation, and the distance to the edge of date palm plantation. Variation partitioning analysis revealed that the pure effect of tree physical characteristics (tree height and DBH) was robust in explaining the occurrence of Turtle Dove nests (adj. R2 = 0.52, P = 0.001). For an efficient management of this Saharan population, special attention should be paid in the short term to keeping high date palm trees while ensuring, in the medium and long term, the presence of different-sized palm tree classes at each exploitation. There is no doubt that date palm plantations of Biskra are of paramount importance because they offer good opportunities for consolidating and improving the knowledge on this threatened species and other species at the Sahara edge.

We present the first detailed study of population dynamics, breeding biology and egg measurement of Common Terns. During six years (from 2004 to 2009) of monitoring, from mid-May to mid-August, 74 Common Terns individual were recorded at Laouinet small island, El Tarf, northeast of Algeria, witha finite population growth rate that indicated an alarming population decline(λ = -0.62: Lambda). Sterna hirundo build its nests (n = 37) in the northeast at a mean distance of 7.58 m from the closest edge of rocks. The nests were closed and ovoid, constituted mainly of mussel shells Sandpit, stems and leaves. Incubation was performed by pairs of common tern and lasted 25.5 ±3.4 days. We recorded a clutch size of 1 to 3 eggs with mean clutch size of 2.45±0.65 (41.24±0.83 × 30.46±0.62 mm). The egg parameters (volume, mass, shape index) varied between the six years of the study. The egg volume (19.24±0.87) depended more on egg width (30.46±0.62), however the egg shape (0.73±0.20) depended negatively on the egg length (41.24±0.83) but not on the egg width. Our results also showed a stabilized hatching success and a best estimation of breeding success. The hatching success did not vary between years: 70.5% in 2004, 68.75% in 2005, 71.42% in 2006, 71.42% in 2007, 69.23% in 2008 and 69.23% in 2009.