Thanks A.T. for confirming my suspicions. I've inquired with the hatchery twice and provided these same photos, and both times they said male Leghorns grow faster than female Leghorns. I weighed the two suspect birds again yesterday. One gained 5 ounces and the other 4 ounces is just two...
I bought Pearl (white) Leghorn chicks from {*******} hatchery, both genders. I've always been very happy with my orders from this hatchery in the past. I emailed the hatchery last week and they assured me that male Leghorns do indeed grow very fast. I'm going to call on Monday to question...