UTTAR PRADESH JOURNAL OF ZOOLOGY

Eggshells in birds are primarily composed of calcium carbonate (CaCO₃), which provide mechanical strength and protection to the developing embryo. In this study, CaCO₃ content in the eggshells of the domestic hen (Gallus gallus domesticus) as a control species, compared with three wild bird species — Baya weaver (Ploceus philippinus), Spotted munia (Lonchura punctulata), and Red-wattled lapwing (Vanellus indicus) — collected from different districts of the Marathwada region of Maharashtra, India. Eggshells were collected from poultry farms and natural nesting sites, then cleaned, dried, powdered, and analysed using a simple acid-base back titration method involving hydrochloric acid (HCl) and sodium hydroxide (NaOH). Among the species, the Red-wattled lapwing exhibited the highest average CaCO₃ content (95.18% ± 1.95), followed by the domestic hen (94.93% ± 0.92), Baya weaver (93.20% ± 2.53), and Spotted munia (91.50% ± 2.43). Two-way analysis of variance (ANOVA) revealed statistically significant differences among species (F = 28.74, P < 0.001), districts (F = 4.79, P = 0.0118), and their interaction (F = 14.64, P < 0.001). These findings provide important baseline data for avian ecological studies and suggest that nesting strategies and habitat variability play key roles in eggshell mineral content. The use of backyard-raised hens as a domesticated control enhances the ecological relevance of the comparisons and highlights the utility of simple analytical methods in avian physiology and conservation research.