Wildlife Crossings Are Nice, But Habitat is Better

You may have heard that the Arizona Game and Fish Department biologists conducted a marathon aerial capture effort last week. The captures are part of ongoing research studies aimed at facilitating safer wildlife movement across roadways. This is great news, but wildlife crossings alone won't suffice to preserve wildlife populations. What more can we do? Read on...

AGFD Biologists collared 10 pronghorn antelope in the Chino Valley last week. The GPS collars will provide detailed movement data that will pinpoint exactly where crossing structures should be placed to keep the herds roaming freely.

Wildlife crossings in the Chino Valley can't come quickly enough. If you've followed the plight of the pronghorn in the valley, you know that various herds have already been walled in by roads, fences, and housing developments sprouting up like so many weeds (didn't know about pronghorn's inability to cross fences? check out this video of pronghorn trapped on a highway).

In fact, the herd trapped in Willow Valley may be doomed to "die out" there. They've been effectively isolated by urbanization. They can't leave because they are surrounded by housing developments, golf courses, and major thoroughfares. They can't exchange genes with other populations since there is no way in or out, so even if they do manage to survive on their urban island, they will eventually succumb to inbreeding depression, and no, that doesn't mean that they will get very very sad.

Wildlife Crossings are great. They provide a way for animals to cross highways safely and make the landscape more permeable-- connected wildlife populations can thrive, roaming and reproducing freely and avoiding the perils facing small, local populations trapped in isolated habitats. Crossings can prevent the Willow Valley scenario from happening to pronghorn herds in the future.

But here's the catch: Crossings don't mean a thing if there isn't any habitat to cross into. Building crossings in the Chino Valley can only help the pronghorn if there are matching efforts to conserve pronghorn habitat on both sides of the crossings. With the ongoing rampant development in the valley, it's entirely possible that by the time the crossings are built, there will be a stripmall or cookie-cutter housing tract slated for either side of the overpass. And they will probably be named something like Pronghorn Hills Shopping Plaza, or Antelope Flats Community....but I digress.

My point is that conserving land should go hand in hand with building crossings. This will require a proactive collaborative approach by the agencies and conservation organizations to identify and acquire key wildlife habitat in the area.

AGFD seems to be way ahead of the game, a leader among state agencies in terms of their research and dedication to building wildlife crossings. I hope that we can leverage their work with parallel efforts to conserve wildlife habitat and ensure the functionality of wildlife crossings.

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