Abstract
Wild rats, Rattus spp, have adapted so well to urbanization that humans may be obligatory to their survival. Consequently, rats foul human food sources, predate threatened fauna and serve as reservoirs for disease, costing the US economy $19 billion in losses year -1. Urban rat ecology however, remains vastly unexplored because these animals are cryptic, crepuscular, difficult to identify, and hazardous to handle. Additionally, the high-rise buildings that block satellite link-ups, underground sewers and subway tunnels, and rebar enforced concrete covered landscape make it difficult—if not impossible— to track urban animals using traditional radio telemetry. Consequently, there are few ecological studies with free-ranging urban rats. Therefore, we set out to monitor the behaviors and health of free-ranging rats in metropolitan New York. Recognizing that wild rats are attracted to live laboratory-reared conspecifics and that they are sensitive to pheromones, we used soiled rat bedding to repeatedly attract animals to a Remote Frequency Identification (RFID)- based antenna with camera-trap and load cell (scale) for collecting weights. We captured and micro-chipped 13 rats within 50, 30 and 10 m from our antenna and followed their movements. Seven of the 8 animals released within 10 m of the antenna, visited the RFID antenna lure 398 times over 41 standardized days. Males (2.7 visits day-1) visited the antenna at the same frequency as females (2.7 visits day-1; P>0.5), and both sexes spent similar time dwelling at the pheromones (M, 2.9±0.9 sec; F, 2.4.±0.4 sec; P>0.05). The passive integrated transponder (PIT)-tag worked free on the lone individual that did not participate. Within our population, female activity peaked between 6am and 7pm, while males visited throughout the day. Our results demonstrate the potential to safely overcome the primary barriers that have impeded urban rat ecological studies. We used pheromone-based lures to attract micro-chipped rats, irrespective of sex or age-class, where their individual identities, behaviors and pathogen loads could be consistently recorded. We discuss the potential for similar assays to help address several longstanding knowledge gaps in the literature regarding pathogen monitoring over time and space, rat dispersal patterns, population parameters and seasonal migrations through corridors.
Highlights
Rattus spp, have adapted so well to human settlements that humans may be obligatory to their survival (Aplin et al, 2003)
Our objectives were to trial a novel method to overcome the two principal barriers associated with remote sensing of wild rats in an urban environment, animal handling/deployment of tracking devices and monitoring of those devices following release
Realizing that female rats are more difficult to trap than male rats (Firth et al, 2014), and that improved trapping of females is essential for the improved use of immuno-contraceptives, we were interested in learning whether female rats could be lured to the Remote Frequency Identification (RFID) antenna ( “antenna”) using pheromones, and where their individual identities and behaviors could be captured on video
Summary
Rattus spp, have adapted so well to human settlements that humans may be obligatory to their survival (Aplin et al, 2003). Their importance as reservoirs for pathogens such as Salmonella (Hilton et al, 2002), Toxoplasma (Berdoy et al, 2000), Leptospira (Athanazio et al, 2008), Rikettsia, Bartonella, and Hanta (Firth et al, 2014) rises They foul food-stuffs, cause structural damage by gnawing on cables and vehicle wires and are suspected of instigating the majority of building fires’ of unknown origin’. Rats have decimated native species of birds and reptiles by consuming eggs and live young (Jones et al, 2008) All together, they cause $19 billion in losses to the US economy, with $1.3 billion in New York City alone (Pimentel et al, 2005). Governing human behavior on a large scale, is tenuous, and there are few means to control rats based on their behavioral predispositions
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