The fauna of the National Park of Wielkopolska is characterized by a huge multitude of species belonging to various systematic groups. Central European and Eurosiberian The species are predominant in the Park.

The richest group are the invertebrates, with the most numerous representation of insects, with over three thousand species. The forests are also full of beetles.

Among them are such protected species as the stag beetle or cerambyx cerdo, but also the more common ones which actually damage the trees, among others, pine trees - two species of tomicus piniperda, phaenops cyanea (pine pest) and striped ambrosia beetle. Dry and warm locations are inhabited by orthoptera, such as the great green bush cricket or the field cricket as well as hymenoptera, such as, among others, the southern wood ant.

The world of arachnida is also extremely richly represented. From some more interesting species, it has been determined that you can find the Argiope bruennichi spider here, the biggest representative of the araneidae family in Poland, and the water spider - the only species in the country which spends its whole life under water. Mollusks form another important group of invertebrates. There are around 104 species of such animals present in the Park, among others, the zebra mussel and two species of snails, including the helicella obvia.

The world of vertebrates is equally rich; it includes fish, amphibians, reptiles, birds and mammals. Fish are represented by around 26 species. Among others, pike, vimba and asp have their permanent spawning sites in the Warta River. In the lakes you can find numerous perches, breams, tenches and eels. It has been determined that in the Park you can find all of the amphibians naturally occurring in lowland Poland. The rare European tree frog and natterjack toad are worth noting here.

Five species of reptiles naturally occur in the Park: smooth snake, grass snake, slow worm, sand lizard and common lizard. All the species listed above are protected by law.

Birds in the Park are represented by around 220 nesting and migrant species. It is worth noting some of the rare ones, such as the Eurasian roller, common kingfisher and the black woodpecker. To speak of birds of prey: in the forest and over the meadows you can notice the black kite. Near the fields you can observe the common buzzard, and near the marshes you can get a glimpse of the western marsh harrier. Over the lakes mallards, garganeys, green-winged teals and great crested grebes are often to be seen. 

Around forty species of mammals live within the area of the Park. From insectivorous mammals, you can observe, among others, the sorex, which is the smallest mammal in Poland. This area is also inhabited by numerous species of bats and rodents. To list a number of predators: martens, badgers and foxes, among others, live in the Park. The large forest area is a place of refuge for numerous deer, roe deer, and boars.