Jirlău Nature Reserve has the same characteristics as the other two lake-reserves (Balta Albă and and Balta Amara), with the specificity that although the two ponds – Jirlău and Trup Vișani – are separated by a dam, they can be considered as one biogeographical unit, especially that they linked by a channel. The water supply comes from underground springs and via an adduction channel from the Buzău River, built after the fishing facilities were set up.

Trup Vişani has a rich aquatic vegetation, typical of the wetlands of the plain (reed, rush, rogoz, plutică – this one occupying large areas, which in summer form a floating vegetation-carpet).

More than 100 bird species, aquatic and non-aquatic, nesting or passage species, whose presence varies depending on the season, have been reported in this nature reserve. Thus, in summer most birds are cantonated in the Vişani pond area, while in winter they can be seen in large numbers on the Jirlău pond.

Among the species of birds nesting in the Jirlău-Vişani ponds and which are of particular importance according to the AIA criteria, we mention: the yellow heron, the ragging duck, the red duck, the evening falcon, cristelul de câmp, the white-cheeked tern and the European bee-eater.

Besides these, there are other bird species nesting here, which even if they do not meet the AIA criteria, contributed to the designation of the area as an avifaunistic area. Of these we mention: corcodelul mic, corcodelul mare, corcodelul cu gât negru, stârcul pitic, lebăda de vară, călifarul alb, raţa lingurar, nagâţul, chirighiţa neagră, ghionoaia verde, ciocârlia de câmp , ciocârlia de Bărăgan, pietrarul sur, sfrânciocul roşiatic, sfrânciocul cu fruntea neagră.

From the migratory species we mention: pelicanul comun, cormoranul mare şi cormoranul mic , lebăda de iarnă, ţigănuşul, lopătarul, gârliţa mare, raţa mică, raţa suliţar, şoimul călător, piciorongul, ciocîntorsul, bătăuşul, chira de baltă, prigoria, sitarul de mal, culicul mare, fluierarul cu picioare roşii.

During the dry years, when the air temperature is very high, the evaporation is greatly increased and the water level in the two ponds decreases appreciably. In the winter, the water in the ponds freezes almost entirely, leaving only small spots free, which become a refuge for all species, both sedentary (especially for seagulls and large ducks) and migratory ones (gârliţa mare, raţa mică, rața sulițar).

The activities being conducted in the nature reserve area that have a negative impact on the reserve are agriculture, household waste management, traffic and car transport, hunting and poaching.

As aquaculture and fishing activities take place in the perimeter of the reservation, the company carrying out this kind of activities in Trup Vişani  fishponds implemented the project “Conservation of natural heritage in the Vişani Fishery Development within the Natura 2000 ROSCI0005 site”.