Analysis of reproductive behavior in male pigeons in the White Mirthys and Egyptian Baladi breeds injected with testosterone propionate

Abstract Background In pigeons, reproductive success is driven primarily by male courtship and copulatory behavior, both of which require threshold levels of circulating testosterone. This study investigated the effects of exogenous testosterone propionate (TP) injection on serum testosterone levels, aggressive behaviors, sexual displays, nest defense, parental care, reproductive cycles, and squab mortality in two pigeon breeds ( Columba livia ): White Mirthys and Egyptian Baladi. Methods A total of 27 adult pairs of White Mirthys pigeons and 27 adult pairs of Egyptian Baladi pigeons were randomly assigned to three experimental groups ( n = 9 pairs per breed per group; total N = 54 cages). Treatments consisted of male-directed subcutaneous injections of either a vehicle control (CON; ethanol and sesame oil mixture) or TP at doses of 1 mg/kg (T1) or 2 mg/kg of body weight (T2). Results Baseline serum testosterone was 47.9% higher in White Mirthys than Egyptian Baladi pigeons ( P < 0.001). Repeated-measures analysis showed a significant Time×Treatment interaction ( P < 0.001) as TP induced dose-dependent elevations in both lineages. TP heightened aggression; female and squab pecking increased uniformly ( P < 0.001), while a significant Breed×Treatment interaction ( P < 0.001) governed squab predation, which surged exclusively in White Mirthys high-dose groups but remained suppressed in Baladi. For sexual behavior, strutting showed a significant interaction ( P = 0.003), suppressing earlier in White Mirthys (T1) before converging at T2, whereas vocal nesting and courtship feeding followed identical quadratic trajectories ( P < 0.001). Brood care feeding exhibited a significant interaction ( P < 0.001); TP entirely abolished the Baladi breed’s superior baseline, suppressing provisioning to a near-zero floor across both lines. Defense metrics plateaued uniformly ( P < 0.001). Offspring survival was compromised via a significant Breed×Treatment interaction ( P = 0.002); mortality rose from 5.6% (CON) to 15.2% (T2), peaking at 23.1% in White Mirthys due to neglect and aggression, but remained insulated at 5.6% in Baladi. The hatching-to-laying interval shortened exclusively in Baladi T2 pairs to 25.6 days ( P = 0.021). Conclusions In conclusion, exogenous testosterone propionate administration was associated with increased nest defense but reduced visual courtship, suppressed paternal provisioning, and higher squab mortality. Furthermore, these behavioral shifts were significantly modulated by breed background, with the White Mirthys lineage demonstrating marked vulnerability compared to the insulated resilience of the native Egyptian Baladi breed.