Ackerdijkse Plassen is a nature reserve

Nature reserve

A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...

 in Oude Leede, a village in the municipality of Pijnacker-Nootdorp

Pijnacker-Nootdorp

Pijnacker-Nootdorp is a suburban municipality in the Randstad conurbation in the Netherlands, in the province of South Holland...

, (south of Delft

Delft

Delft is a city and municipality in the province of South Holland , the Netherlands. It is located between Rotterdam and The Hague....

 and west of Berkel en Rodenrijs

Berkel en Rodenrijs

thumb|250px|right|Town signBerkel en Rodenrijs is a town and former municipality in the Western part of the Netherlands, and is located in the Dutch province of South Holland.- History :...

). It is one of the most important bird areas in the Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

. In addition to 115 species of breeding birds, the ponds are visited annually by about eighty species of migratory birds, such as greenish warbler

Greenish Warbler

The Greenish Warbler and Green Warbler are widespread leaf-warblers throughout their breeding range in northeastern Europe and temperate to subtropical continental Asia. This warbler is strongly migratory and winters in India. It is not uncommon as a spring or early autumn vagrant in Western...

, Greater short-toed lark

Greater Short-toed Lark

The Greater Short-toed Lark or sometimes just Short-toed Lark is a small passerine bird. It breeds in southern Europe, northwest Africa, and across temperate Asia from Turkey and southern Russia to Mongolia. It is sometimes considered conspecific with Calandrella cinerea...

, short-eared owl

Short-eared Owl

The Short-eared Owl is a species of typical owl . In Scotland this species of owl is often referred to as a cataface, grass owl or short-horned hootlet. Owls belonging to genus Asio are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or may...

, booted eagle

Booted Eagle

The Booted Eagle is a medium-sized bird of prey. It is about in length and has a wingspan of . Like all eagles, it belongs to the family Accipitridae....

, lesser spotted eagle

Lesser Spotted Eagle

The Lesser Spotted Eagle is a large Eastern European bird of prey. Like all typical eagles, it belongs to the family Accipitridae...

, black crowned night heron and osprey

Osprey

The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...

. Konik

Konik

The Konik or Polish primitive horse is a small horse, a kind of semi-feral horse, originating in Poland. The Polish word konik is the diminutive of koń, the Polish word for "horse" . However, the name "konik" or "Polish konik" is used to refer to certain specific breeds...

 provide grazing in the area.

The area contains a restored farmhouse from 1660.

The area is closed to visitors, however there are hiking trails and bike paths around the outside of the area.

The Nature Society took over the management of the area from the Birdlife Netherlands.