Are there really that many land-uses that coincide with heron habitat?  Natural (undisturbed) wetlands, agricultural wetlands, natural riparian/lacustrine, and suburban koi ponds are all that come to mind.  Their habitat is much more specialized than that of, for two examples, English sparrows (I know that House sparrow seems to be preferred, but my dad taught me English sparrow) or White-tailed deer.  Perhaps I am thinking along the wrong lines regarding your meaning of land-use.

In the temperate zone summer season, I see herons daily in riverine hay meadows, solitary or pairs. Occasionally, the white stork forages in the same places as well, single or small groups. In Amsterdam, herons nest in a city park in Amsterdam. 

Following Matthew, I suggest you consider land cover, landscape and season.

My survey area is a comune of Po river delta where are some SCI and SPA in a matrix of intensive agricolture. I  downloaded from local territorial information system the 2007 use land cover layer and I realized the earlier one by satellite imagine interpertation using always Corine Land Cover code: so you suggest me give use land cover listed by Matthew just weight 1and all other one 0? Or do you mean that  I shoud actually give habitats the weights on the basis of heron's local ethologiy ? May be could it more useful contact local specialist ?

This additional information is very helpful.  The distinction between land-use and land-cover classifications is significant here in the USA.

In looking at the Corine land cover codes, I see that while there are several that can easily be weighted at 0, and a few that can be weighted at 1, there are actually many that probably merit an intermediate weighting.  These intermediate ones merit such a weighting based on the probability that they include areas that might serve as habitat for heron guild as much as how suitable they tend to be for habitat.

I agree that there will need to be local input, especially regarding the actual local conditions of land that falls into the various Corine categories.

For some of the intermediate categories, I would actually suggest that instead of giving them a blanket weight you might instead buffer around the weight "1" areas where they adjoin these intermediate ones.  For example.  Instead of giving all woodlands an intermediate value, only give them a non-zero value based on their proximity to wetlands and watercourses (weight "1" areas).  One could similarly buffer at along the shorelines of large water bodies, since the shore areas are the actual habitat.

I'm giving you a straw-man starting point here for your local experts to refine.  This is a quick effort based on the nature of these land covers in the area I live.  I suspect that there are some important differences in the nature of the various land covers as they occur in the Po River valley and so some dramatic adjustments wouldn't surprise me.

I expect it will also elicit some comments here too, and that would be good.

1.1.1=0

1.1.2=0.1

1.2.1=0

1.2.2=0

1.2.3=0.1

1.2.4=0.1 (largely because they don't want birds around airports)

1.3.1=0

1.3.2=0

1.3.3=0

1.4.1=0.3

1.4.2=0.5

2.1.1=0.1

2.1.2=0.3

2.1.3=0.8

2.2.1=0.1

2.2.2=0.2

2.2.3=0.1

2.3.1=0.3

2.4.1=0.1

2.4.2=0.1

2.4.3=0.3

2.4.4=0.2

3.1.1=0.1

3.1.2=0.1

3.1.3=0.2

3.2.1=0.3

3.2.2=0.5

3.2.3=0.1

3.2.4=0.2

3.3.1=0.1

3.3.2=0

3.3.3=0.1

3.3.4=0.1

3.3.5=0

4.1.1=1

4.1.2=0.8

4.2.1=1

4.2.2=0.1

4.2.3=1

5.1.1=1

5.1.2=0.8

5.2.1=1

5.2.2=1

5.2.3=0

Thank you so much for your suggestions ! They are very useful : actaully I meant that at the ouset , so I'm sorry for not being clear