Spatio-temporal relationships between feral hogs and cattle with implicatons for disease transmission
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It is widely recognized that livestock industries are vulnerable to intentional or accidental introductions of Foreign Animal Diseases (FADs). Combating disease is difficult because of unknown wildlife-livestock interactions. Feral hogs (Sus scrofa) could harbor and shed disease in areas used by domestic livestock such as cattle (Bos taurus). Extent of risk logically depends on spatio-temporal interactions between species. I used Global Positioning System (GPS) collars on cattle and hogs in combination with a Geographic Information Systems (GIS) for detailed analysis on movement patterns of these 2 species on a ranch in southwestern Texas, USA. Motion-triggered video recorders were also utilized to determine interspecific activity patterns. I tested hypotheses that spatio-temporal distributions of domestic cattle and feral hogs on rangeland overlap and that interspecific contact occurs. If these posits are true, it is possible that introduced pathogens like foot-and-mouth disease (FMD) could be transmitted from feral hogs to cattle. Using a rate of 1 GPS fix/15 min (96 fixes/day), I found that spatial distribution of individual hogs and cattle overlapped on both the 95% and 50% kernel area use among 4 seasons. Both cows and feral hogs used Clay Flat, Clay Loam, and Rolling Hardland more so than other range sites. During Summer 2004, riparian zones were the most used feature, identified at 14% (2,760/19,365) of cattle and 70% (445/632) of hog fixes. Other than brush strips, cattle and feral hogs primarily interacted at riparian zones, fencelines, and roads. There were no direct interspecific contacts evident from GPS data, but 3 cases were recorded from video data. Indirect interspecific contacts that may be sufficient for disease transmission occurred much more frequently (GPS = 3.35 indirect contacts/day, video = cows follow hogs: 0.69 indirect contacts/day and hogs follow cows: 0.54 indirect contacts/day). Research results suggested that both species often travel along the same roads and fencelines to water and food sources, especially during extreme heat and low-precipitation conditions. This research provides basic information needed to improve models for management of FAD outbreaks in the U.S., based on specific knowledge of landscape usage and movement patterns of feral hogs and cattle.
Deck, Aubrey Lynn (2003). Spatio-temporal relationships between feral hogs and cattle with implicatons for disease transmission. Master's thesis, Texas A&M University. Texas A&M University. Available electronically from