Differential Particle Size Ingestion: Promoting Target-Specific Baiting of Feral Cats

Abstract

Predation by feral cats (Felis catus) is believed to threaten the conservation of a range of terrestrial vertebrates in southeastern Australia, and new baiting techniques are sought for broad‐scale control of feral cats. In southeastern Australia there are 34 native mammals that may consume meat baits, and ways to minimize their exposure to bait toxicants are needed. We determined the potential of cats to ingest larger particles relative to most nontarget species as a mechanism to increase baiting selectivity. Feral cats reliably ingested inert, spherical bearings up to 4.7 mm in diameter when the bearings were implanted within a specialized bait medium. Presence of bearings did not affect bait consumption relative to untreated baits. Repetitive ingestion was highly reliable in the first 9 days of a feeding trial and diminished only marginally in a consecutive trial. We presented captive plains rats (Pseudomys australis), fat‐tailed dunnarts (Sminthopsis crassicaudata), eastern barred‐bandicoots (Perameles gunnii), and northern quolls (Dasyurus hallucatus), with baits containing 4.7‐mm‐diameter coated pellets formulated with the marker dye rhodamine B (RB). Exposure to the marker dye for each species was not biased to individual or day of presentation. Exposure to RB in the pellet occurred in only 3.1–6.5% of presentations for each species, and the mean daily mass of the pellet in gkg−1 day−1 ingested was 0.078–0.01% of the mean bait mass in g kg−1 day−1 consumed. Pellet presentation greatly reduced (P ≤ 0.001) the exposure of wild native rodents to RB relative to directly injected baits. Exploiting differential particle size ingestion between feral cats and nontarget species could potentially reduce exposure of many nontarget mammals to bait toxicants and decrease the risk of baiting to nontarget species.

Increasing the target-specificity of ERADICAT® for feral cat (Felis catus) control by encapsulating a toxicant

“…ERADICAT ® is a sausage bait with a relatively soft/moist texture, consisting mainly of kangaroo meat. Marks et al (2006) provide further description. Feral cats will readily consume this bait (Algar and Burrows 2004).…”

“…Ongoing research has revealed two methods that may be used to make feral cat baits more species specific (Marks et al 2006). A synthetic compound named para-aminopropiophenone (PAPP) has been identified as an ideal toxicant for feral cat control given the reported difference in susceptibility between cats and other species as well as other factors such as the apparently humane mode of action (Savarie et al 1983;Marks et al 2004).…”

“…Marks et al (2006) report on the use of a pelletised delivery technique that demonstrated that captive feral cats reliably consumed hard pellets up to 4.7 mm in diameter while a range of captive and wild non-target species detected the pellet during feeding and rejected it.…”

“…In cats the canines are long and the carnassial teeth are highly specialised and adapted to cutting and shearing, as are the molars (Gilbert 1975;Marks et al 2006). Therefore, none of the teeth are suitable for chewing (Jones 1989).…”

“…Therefore, none of the teeth are suitable for chewing (Jones 1989). The loss of grinding premolars in cats has reduced their chewing efficiency and led to their propensity to swallow relatively larger portions of food and inert material such as bone (Jones 1989;Marks et al 2006). The tendency to swallow large portions of food has been confirmed in dietary studies of feral cats (Brooker 1977).…”