I am trying to analyze temporal change in bird density in response to land-use attributes. I have created a base grid index feature to join both my bird and land-use data to. I then hope to treat each grid cell as a survey site and pull summed values to compare over time. I am having a difficult time conceptualizing the best method to achieve this. Thus far, I have created a summary table of land-use activity per grid cell per year. I thought I could then join this table to my grid index feature by grid cell ID, but the join is only accepting the first summary year per cell. I though I understood the 1:M join rules but apparently not. Please help!