Population of animals has always either increased or decreased, most of the time it decreases due to limit factors such as water, food, place and temperature. I have researched a bit about some endangered animals and decided to set this on Slovakia. Most of the animals in Slovakia are taken care of, either with care, or people sponsoring them, however there are still some endangered animals.
Some of these for example are:

• Dalmatian Pelican (Bird)

 

•  Apollo Butterfly (insect)

 

• Danube Salmon (Fish)

• Egyptian Vulture

Most of the animals I found, were snails which I thought was pretty interesting becasue I didn't know snails could be endangered and surely not in Slovakia. Population growth isn't always bad, sometimes, when the species is about to die out, it might be the most sufficient thing to do. Populations can be limited to some factors such as water, food, space and weather, these are called limiting factors. If a population doens't have enough of these, or it doesn't fit them and their environment, they will stop reproducing and the population goes down. Birth rate and death rate also affect a population, if too many of one kind are born, it can cause problems but the opposite can do the same. This is why many countries and cities are starting to take control over the animals they posses, this way they can give them what they need to survive, but make sure they stay a certain amount. The rest is up to mother nature. But after all every country, continent or city, has it's own animals needs and even thought they don't always think at animals and how their actions could affect the populations, there are still some people who are trying to change that.
http://www.earthsendangered.com/search-regions3.asp
Glenn, C. R. 2006. "Earth's Endangered Creatures" (Online). Accessed 30/11/2011 at http://earthsendangered.com.