The data from several weather stations in Western Algeria show a semi-arid climate during last decades. The entire study region showed a great variability in the occurrences of the first and second rainy days in the year. This variability is associated with a positive trend, showing a continuous increasing aridity in the south Mediterranean and the late arrival of the rainy season is well marked. The rainy season in the north of Algeria, spreads from September to June. The origin of the rains differ according to the seasons. The rainfall from June to October is of localized stormy origin, whereas in winter, the rainfall comes from the classical atmospherically perturbations arriving from North or North West. This work objective was to give a definition of the rainy season onset and to show its inter - annual variability according to the Niño and Niña years. The El - Niño phenomenon by its positive and negative phases seems to affect the start of the rainy season. The variability of the rainfall onset indices is very significant. There is a relative stability of the rainy season length over the long term period. A significant delay in the precipitation onset was observed during certain years. A method to define rainy season onset based on daily rainfall data from a weather station in the Algerian highlands was proposed. This approach is based on a climatic point of view, using a frequency analysis of precipitation and dates of their first occurrence. It delays the first heavy rain day (20 mm) when La - Niña settles. If EL-Niño settles, the first heavy rain (20 mm) day will be earlier. These results will improve the probabilistic forecasts of the beginning of the rainy seasons, the cessation as well as the lengths. This work is a preliminary confirmation that the El-Niño phenomenon really affects the Mediterranean climate.

According to the data obtained in the autumn-winter period, the excess of PM2.5 in air during the schoolday after a short stay by pupils in the school yards was 1.5 –2 times. The PM2.5 concentration in the autumn - winter period was up to 1.5 times higher than that of the spring – summer time. High concentrations of dust particles are observed in areas close to heavy traffic in winter in the South-Eastern part of the city. Low concentrations were recorded in the autumn-winter time in areas adjacent to forests in the North –Western part of the city of Tiaret. However, the protective function of forest stands in the spring – summer period in the North-Western part of the city of Tiaret is less evident. The need for introduction of several nature protection measures in the city is obvious. Among them: fuel quality control and fines for the use of low-grade fuel, increasing the density of trees and shrubs in the city in the areas uncovered by vegetation.

Understanding the food habits of wild animals is crucial for the effective management of wildlife. We investigated the diet of the Cape hare in the Djebel Messaâd mountain, northern Algeria, from September 2021 to August 2022. A total of 120 samples of faecal pellets (ten samples each month, 15–20 pellets per sample) were collected and analysed by means of 30 microhistological analysis. Over the year, the Cape hare consumed a total of 30 plant taxa from 11 families. Average monthly diet comprised mainly of Poaceae (grasses) with a relative abundance of 69.02%, Fabaceae (18.58%), Cupressaceae (6.27%), and eight other families with less than 3% of each. Besides the dominant grasses, forbs were the second most abundant botanical group (20.96%), followed by shrubs and trees, which were consumed in lower proportions (10.02%). Overall, Cape hare's diet was stable from spring to winter, with no significant differences observed both in terms of species richness and diversity. In our study area, the Cape hare can be regarded as a grazer species. Proper management measures should be taken to maintain habitat diversity and prevent its degradation such as overgrazing by livestock, which can reduce the availability of grass species for Cape hare populations.

We investigated the feeding ecology of the crested porcupine Hystrix cristata in a semi-arid area of its northwestern Algerian native range over 8 months (September to April). Our results from micro-histological analysis based on faecal pellets revealed that this strict herbivore ate only 10 plant species, 8 wild and 2 cultivated, belonging to 9 families including Lamiaceae, Palmaceae, Poaceae, Ramnaceae and Fabaceae. The autumn diet was dominated by Thymus algeriensis, Ziziphus lotus, Chamaerops humilis and Triticum aestivum, the winter diet by T. algeriensis and C. humilis, and the spring diet by Muscari comosum, with a large amount of Vicia faba and T. aestivum. We confirm the role of this rodent species as a generalist herbivore which barely feeds on cultivated plants when wild resources are diverse and abundant.