White leghorn about a year old stopped laying

[jodiplunk]

I have 6 lovely birds. Various breeds who have the free roam of our back yard. They have constant water. Graze on bugs all day but have dry food available in their coup too. They all seem happy and content. No one is an outsider. My white leghorn who is probably one of the leaders suddenly stopped laying a few weeks ago. Nothing has changed. Her behavior is still the same. She runs to me for scraps with the others when they hear the door open. She's scratching in dirt. Taking dust baths. Eating and drinking. Nothing seems wrong with her. She's just not laying as the rest are. No change in environment or stress that I'm aware of. Any ideas? I have noticed a few white feathers around this week but not many. It's only July. It has been hot in the high 90's often and humid. I just put it down to the heat but after doing a bit more research I'm confused as to whether this would be the cause? She doesn't seem broody. Any ideas? Anything I can so to help her start laying again?
Thanks in advance for any help!

 

[sourland]

She may have a hidden nest somewhere in the yard, or she may be starting to molt, or she may just be taking a break - sometimes they do.