Somewhere around $50 million per year in crop damage...
Not to contradict you, Art, as I have seen and used that number as well, but I think it is out of date. I know that there are different state offices and university people that have come up with various other estimates, but I think the $50 million has been used for at least the last 4-5 years.
Here is a 2007 article mentioning it as $52 million in crop damages...
Given that the hog population is supposed to be growing, you would expect the number to go up. Recently I have been seeing articles stating losses in the hundreds of millions, but the damages also include things other than crops.
For example, here they mention $400 million over from Aug 2011.
This article from a few days ago still has pigs only doing $52 million in crop damages, but $550 million overall.
I am thinking that the crop damages have to have increased over 4-5 years. I don't think anyone has actually recalculated the crop damage estimate. In 2007, we were thought to have 2 million feral hogs and now we supposedly have 2.6 million, so more crop damage would be expected not only because of the increase in the hog population, but also because of inflation. Using 3% as an annual inflation average for the four years following the 2007 start date estimate, if pigs were doing the same physical amount of damage over the years, the damage values today would be over $58.52 million.
Of course, a lot of their damage is in ways that are not directly able to be tabulated such as their rooting activities promoting soil erosion, especially on inclined properties and in forests. Hog-loosened soil combined with rain events increases the sediment load of streams and rivers and so there is higher turbidity. Higher turbidity negatively affects aquatic ecosystems in numerous ways. Given the countless numbers of dammed streams and rivers in Texas, much the inflated sediment load carried by the stream is dropped when the flowing water reaches the pools/lakes/reservoirs where the current velocity drops. As such, the dammed pools fill with the eroded sentiments at a faster rate and shorten the use life of the reservoirs. Also, the higher the sediment load in the water, the greater the cost to filter and purify the water for consumer consumption.
Of course, hogs are not alone in contributing to the sediment load of streams/rivers/lakes. Their current impact is probably miniscule, but increasing.
Another increasing problem is vehicle/pig collisions. They are not to the point yet of darting out in front of cars like deer do, but roadkilled pigs are becoming a more comon sight which means there is going to be a corresponding increasing amount of vehicular damages (except maybe on 18 wheelers) and these damages I don't believe are being studied yet like they are for deer.
This article mentions pig vehicle collisions are up, but not by how much or how many that had been reported.
This article doesn't say how many either, but estimates the average vehicular damage at $1200 per collision with hogs.
The damage estimate matches this South Carolina limited study dated 2011...
...but it appears to be the PowerPoint version of a paper by the authors dated from 2007...
...and so the vehicle damage amounts have probably increased as well because of more hogs being hit and in accounting for inflation.
Higginbotham from Texas A&M estimates 10,000 vehicle/pig collisions per million pigs of population. I don't quite follow how he came up with 1% of pigs being hit given he didn't know have many of such collisions have occurred or just what the actual hog population in Texas is. If based on the European data noted, then his estimate would be very conservative. Assuming that there are 2.6 million hogs in Texas with 1% being hit per year and with a conservative (out of date) estimate of $1200 damage per collision, then you would be looking at $31.2 million in damages alone from vehicle/pig collisions per year.
If that many are really occurring, then my guess would be that insurance complanies are probably tracking the number of vehicle/pig collisions filed for each year and the amount of damages incurred, but I don't see that sort of data presented on the web anywhere. Even if it was, it would undoubtedly be a conservative estimate as well given the number of drivers that don't carry collision insurance and hence don't file claims when they strike pigs on the road.