Ok, I finally found something. I don't know anything about Sparks' zoning codes, but hopefully you know what zone you live in. This looks like you're allowed to have up to 12, if you live in district R1-40. It also says you need to have an acre of land, but I'm not sure if that's for all livestock including chickens.
Section 20.29.040 Location of livestock.
A. Livestock used for production and commercial purposes may be kept only in the agricultural districts, A-5 and A-40, of the City.
B. Livestock used for recreational purposes may be kept only in the agricultural districts, A-5 and A-40, and residential district, R1-40, of the City, subject to the following restrictions:
1. The minimum size of the lot on which livestock used for recreational purposes must be at least one acre;
2. No more than one head of livestock may be maintained per twenty thousand square feet of land area;
3. The keeping of poultry and large fowl or birds is limited to no more than twelve per acre of property;
C. Other than as provided above, it is unlawful to keep livestock for any purpose in any other zoning district of the City.
http://www.cityofsparks.us/municipa...ng-and-land-use-controls/chapter-2029-anima-0 ETA: A year or so ago, my daughter and I had a conversation about the legality of chickens in Sparks. (She's 11 years old.) She was staying at her dad's house and heard roosters, and was about to tell on someone. I mentioned that someone could lose some really loved animals if she did that, and often it was just kind to look the other way and close your window to the rooster crowing if it's not hurting anyone. Luckily the conversation didn't go further into the morals of right and wrong. She understood that some things aren't worth getting technical over if it means that someone could lose their beloved pets. Hopefully this isn't an issue for you at all! I think, even if they aren't legal there, most of your neighbors won't even know that. They're so common in Reno that hopefully people will just assume it's the same all over Sparks.