IMPACT OF URBANIZATION ON BIRD DIVERSITY, ABUNDANCE, SEX RATIO, MIGRATORY TRENDS, AND BEHAVIORAL PATTERNS IN DERA ISMAIL KHAN

Urbanisation is among the most pervasive and rapidly expanding forms of anthropogenic land transformation, and its consequences for avian communities in the developing world remain poorly quantified. This study assessed how a gradient of urban development affects bird diversity, abundance, adult sex ratio, migratory composition and behaviour in and around Dera Ismail Khan (D.I. Khan), a rapidly growing city in Khyber Pakhtunkhwa, Pakistan. A quantitative, stratified field survey was conducted across three zones—an urban core, a suburban transition belt and a rural periphery—using fixed-radius point counts replicated seasonally over a twelve-month cycle. Diversity was quantified using the Shannon–Wiener index, Simpson's index, Pielou's evenness and Margalef's richness, and inter-zone differences were tested using analysis of variance and non-parametric alternatives. Results demonstrated a monotonic decline in species richness (from 53 species in the rural periphery to 24 in the urban core) and diversity (H′ = 3.41 to 2.31) with increasing urbanisation, accompanied by rising numerical dominance of a few synanthropic exploiters such as the house crow, common myna and rock pigeon. The adult sex ratio became progressively male-biased toward the urban core, migratory species were markedly under-represented in the built-up centre, and urban migrants showed advanced spring arrival and delayed autumn departure. Behaviourally, urban birds displayed shorter flight-initiation distances, elevated vigilance, reduced foraging time and higher minimum song frequencies. The findings indicate that unmanaged urban expansion in D.I. Khan is driving biotic homogenisation and functional simplification of the local avifauna, and they underscore the need for green-space retention and evidence-based urban planning to conserve regional bird communities.