Fertility patterns in Nigeria are high and widely skewed away from the targets of the country’s population policy. As population growth is fueled by natural increase and migration, and with spatial disparities in fertility preferences among the different ethnic groups in Nigeria, this study investigates the fertility behavior of ethnic migrants in their destinations, the place-effects on such behavior, and the convergence or otherwise of the behavior with fertility behaviors in the migrants’ places of origin and destination. Explanations for the behavioral pattern are provided in the hypotheses of migrant fertility and in the sociodemographic confounders of the behavior. Study data was extracted for the three major ethnic groups in Nigeria from the Nigerian Demographic and Health Survey. Median numbers of children ever born (CEB) were 7, 6, and 4 for the Hausa-Fulani, Igbo, and Yoruba ethnic groups respectively. Relative to the destination fertility patterns, Hausa-Fulani and Yoruba migrants had lower CEB in Igboland while Igbo and Yoruba migrants recorded lower CEB in the North-West home of the Hausa-Fulani ethnic group. Whereas the Igbo migrants maintained an equal CEB with their Yoruba hosts, the Hausa-Fulani group replicated their home fertility behavior in Yorubaland. Overall, the adaptation, socialization, and selectivity hypotheses were found valid for some of the disparities in migrant fertility behavior and the influence of the sociodemographic predictors of fertility behavior varied among the different ethnic groups.