A few thoughts:
1) Copyright - I read a few posts back how you're doing this and it does work; but honestly I would suggest simply putting a notation in text under each picture to denote who took it/owns copyright. A clear visual display that doesn't require hovering over (not everyone will think to do that) and that doesn't require you to spend ages editing photos*
You can also use this as a chance to put a link to the photographer/copyright holders web-page if you so choose/if one is online.
2) Remove any links/tabs or disable them from working on the page until you've content in those sections to show. In general its bad practice on any website to show links to items that don't exist. It leads people to think the site has failed/isn't being updated/has errors etc...
"Coming soon" is also really annoying if several tabs have it up so again dump them until you've got the content to show.
3) From a photography standpoint consider trawling flickr/500pixs/zoochat and inviting photographers to allow you to show their photos. This will allow you to achieve a higher overall standard as at present the site has a lot of variety from some photos looking good to others looking pretty bad. That's poor advertising for the zoo (which honestly IS your intent per species); and for the site itself; suggesting that you're not really that "serious" about it (some might also question your rights to even share when the image variety is so varied).
Note also that bad photos might well advertise a zoo as "bad" for photographers (because you; the author, didn't find anything better htan the poorer photo - suggesting difficult conditions).
4) Slow down with updates - one or two a week on set days at set times is better than all at once; otherwise you run the risk of losing you audience.
*technically even if you've permission to share you won't have permission to edit so you'd have to seek that as well even if you were simply putting text onto the photo. Thus text underneath works well