The estuary of the IJzer River is one of the few places along the Belgian coast that still features some nice nature. Birding depends on the tide, and spending a few hours to cover both high tide and low tide makes for a great (half) day out. I find the site best when tidal amplitude is high (near spring tide) and when I can start at high tide.
The harbour features some mudflats and salty grassland, that (partially) flood during high tide (depending on tidal amplitude). This site looks very different during high tide compared to low tide, so I always try to start at high tide and end at low tide. Depening of the season check for Common Redshank , Spotted Redshank , Grey Plover , Ruddy Turnstone , Common Ringed Plover , Dunlin , Red Knot , Curlew Sandpiper , Eurasian Curlew. In winter ducks can also be common ( Northern Pintail , Common Teal , Eurasian Wigeon). Other birds are Little Egret , Grey Heron , Meadow Pipit , House Sparrow. Both high or low tide can be good for seals.
From the harbour walk (or bike) in the direction of the coast. Between the harbour there are some viewing points, but often not many birds are around (except for Grey Partridge ). Near the coast follow the big road to the left until you arrive at the river, and there turn to your left until you have decent views on the mudflats along the river. This site is often good at retreating tides, when waders come to the freshly exposed mudflats. More birds are often further away, but they can only be observed from the tower on the other bank. The same species of waders are around, but often you have more Dunlin and allies here. There are also more gulls and often large numbers of Great Black-backed Gull . Check the river channel ( Slavonian Grebe (Horned Grebe) , Red-breasted Merganser) and also the stone banks at the other side of the channel ( Whimbrel , even during winter).
From here you can walk along the channel towards the sea, but this road is closed from 2020 to 2023 (?). When the road is closed return and where you previously turned left (at the gate of the military site) you now continue on a small (new) trail along the fence of the military site towards the lighthouse.At the lighthouse turn left until you reach the river and then turn towards the sea and on to the pier. Note: during spring 2020 also the pier might be closed. An alternative is the pier on the other bank which requires returning to your car and driving to the other bank.
Next to the pier there is a beach that is closed for public for nature conservation. Check for waders and gulls on the beach and along the breakwater: Sanderling , Purple Sandpiper , Ruddy Turnstone , Great Black-backed Gull. Walk on the pier if weather allows and at the end scan the sea. Depending on conditions this can be an excellent site for seabirds with Common Scoter , Greater Scaup , Common Eider , Northern Gannet , Red-breasted Merganser , Red-throated Diver, Kittiwake and maybe Black-throated Diver (Arctic Loon) .
When returning you can check the area between the river and the lighthouse for European Stonechat and Northern Wheatear . At the lighthouse you have acces to the beach. Walking eastward might produce Crested Lark but as the dunes are a military site it is difficult to get good views. In winter check the beach for Horned Lark and Snow Bunting.
Park at the harbour and from here walk or bike. There is a lookout tower on the other bank (payed parking) and also a pier on the other bank (payed parking, sometimes hard to find a parking spot). In some seasons a small ferry crosses the river.
From 2020 to 2023 (?) flood protection works take place in the harbour. Acces to the eastern pier might be difficult. At the time of writing (february 2020) there was a small fence (30 cm high) and the western pier was open (but was closed during much of fall 2019).