This document discusses an interdisciplinary research project studying urban rats in Helsinki, Finland. It notes that rats and humans have shared urban habitats for thousands of years. The project takes a multidisciplinary approach to understand rat populations and disease ecology in the city using methods like track plates, interviews, and analyzing pathogens in rat carcasses. Challenges include the difficulty of longitudinal study and societal attitudes of disgust towards rats. The goal is to better understand rat populations and human-rat interactions in urban ecosystems.

1. Humans, rats and microbes sharing the urban landscape
A multidisciplinary research project on urban rats
Tuomas Aivelo, University of Helsinki
Nina V. Nygren, University of Tampere

2. More-than-human cities
• Humans and rats sharing
habitat for thousands of years
• Rats are one of the most
successful species in urban
areas
• Consequently, the rat is very
(in)famous commensal
Tuomas Aivelo

3. Brown rat (Rattus norvegicus)
• Originally evolved in East Asia
• Spread over the world from
17th century onwards
• Cosmopolitan, though less
common in tropical areas
• Territorial, lives in family groups
Hans-Joachim Pelz

4. Multiple roles of rats
• Synanthropic wildlife
• Experimental animals
• Pets
• Worshipped animals
• Cultural symbols

5. Urban brown rats
• Brown rats present in European cities from
17th century onwards
Puckett et al., 2016
• Replaced black rats in 19th and 20th century
in Finland
• Population sizes and role in urban ecosystem
poorly known
Parsons et al., 2017
• Urban rats have materially shaped our
infrastructures and practices
Hans-Joachim Pelz

6. Why study urban rats?
• Arguably one of the most successful
synanthropic species
• Emotionally and culturally loaded research
subject
• Surprisingly poorly known more-than-human
networks
• Physiologically, developmentally, etc. best
known mammal species
• Environmental, geographical, socio-economic
etc. data readily available in urban areas
• Environmental change could affect rat
populations
Nina V. Nygren

7. Humans, rats and microbes
• Humans and rats partly share symbiont
communities
Himsworth et al., 2013
• Historically rats have spread diseases,
such as plague
• Current potential pathogens: hepatitis E
and Seoul hantavirus
Purcell et al., 2011; Heyman et al., 2004
• Role of antibiotic resistance
Himsworth et al., 2015
Hans-Joachim Pelz

8. Interfaces of human-rat
infections
• When rats are numerous, citizens might
have direct encounters
• Faeces, food contamination
• Via pets, such as cats and dogs
• Professionals encountering rats
• Sewers
Tuomas Aivelo

9. Rat (management) policy?
• Wicked problem
• Urban rat
management networks
• Growing public
awareness of
nonhuman intelligence
and suffering
Nina V. Nygren

10. • Began in January 2018
Otso Huitu, LUKE
Tuomas Aivelo, U. Helsinki
Suvi Huovelin
Tarja Sironen
Windi Musiazari
Nina V. Nygren, U. Tampere
Esa Koskela, U. Jyväskylä
https://www.helsinki.fi/en/
projects/urban-rats

11. Multidisciplinary approach - questions
Disease ecology
• What parasites and pathogens do
rats carry?
• How do rat symbiont communities
vary spatiotemporally?
Population ecology
• How many rats there are in Helsinki?
• How do rat populations vary
spatiotemporally?
Citizen science
• Can rat populations be reliably
estimated via citizen help?
• Are rats suitable study subject in school?
• How do the citizens feel about studying
rats?
Environmental policy
• What kind of networks has rat
management brought into life in
Helsinki?
• How to live with intelligent
disruptive nonhumans?

12. Multidisciplinary approach - methods
Disease ecology
• Carcasses from
extermination companies
• Analysis of helminths,
viruses and bacteria
Population ecology
• Population estimates from
track plates and mark-
recapture Hacker et al, 2016
• Spatiotemporal variation over
the whole city
Citizen science
• Track plates used by students
• Questionnaires and
interviews
Environmental policy
• Interviews of different actors
• Field ethnography on pest
managers, citizens
• Newspaper articles

13. Population estimates
from track plates
• Over 1.000 lower and
upper secondary school
students in Helsinki take
part
• Possibility to have a good
spatiotemporal coverage
• https://five.epicollect.net/
project/helsingin-
kaupunkirotat
Tuomas Aivelo

14. Challenges in studying rats
• Longitudinal studying very difficult
Parsons et al., 2017
• Shame, hate and disgust
• Rats move three-dimensionally – how
to gain access to sewers and tunnels?
• Research ethics
• Disruptive capabilities of rats
Unknown / Helsinki-kuvia

15. Where have you encountered urban rats?

16. References and literature
• Despret, V. (2004). The body we care for: Figures of anthropo-zoo-genesis. Body & Society, 10(2-3), 111-134.
https://doi.org/10.1177%2F1357034X04042938
• Hacker, K.P., Minter, A., Begon, M., Diggle, P.J., Serrano, S., Reis, M.G., Childs, J.E., Ko, A.I., & Costa, F. (2016). A Comparative Assessment of Track Plates
to Quantify Fine Scale Variations in the Relative Abundance of Norway Rats in Urban Slums. Urban Ecosystems, 19(2), 561-575.
https://doi.org/10.1007%2Fs11252-015-0519-8
• Haraway, D. J. (2016). Staying with the trouble: Making kin in the Chthulucene. Duke University Press.
• Heyman, P., Plyusnina, A., Berny, P., Cochez, Artois, M., Zizi, M., Pirnay, J.P., & Plyusnin, A. (2004). Seoul hantavirus in Europe: first demonstration of the
virus genome in wild Rattus norvegicus captured in France. European Journal of Clinical Microbiology and Infectious Diseases, 23(9), 711-717.
https://doi.org/10.1007/s10096-004-1196-3
• Himsworth, C.G., Parsons, K.L., Jardine, C., & Patrick, D.M. (2013). Rats, cities, people, and pathogens: a systematic review and narrative synthesis of
literature regarding the ecology of rat-associated zoonoses in urban centers. Vector-borne Zoonotic Diseases, 13(6), 349-359.
https://doi.org/10.1089/vbz.2012.1195
• Himsworth, C.G., Zabek, E., Desruisseae, A., Parmley, EJ., Reid-Smith, R., Leslie, M., Ambrose, N., Patrick, D.M., Cox, W. (2016). Journal of Wildlife
Disease, 52(2), 418-421. https://doi.org/10.7589/2015-09-238
• Hinchliffe, S., Kearnes, M. B., Degen, M., & Whatmore, S. (2005). Urban wild things: a cosmopolitical experiment. Environment and planning D: Society
and Space, 23(5), 643-658. https://doi.org/10.1068/d351t
• Kirksey, E. (2015). Emergent ecologies. Duke University Press.
• Parsons, M.H., Banks, P.B., Deutsch, M.A., Corrigan, R.F., & Munsi-South J. (2017). Trends in urban rat ecology: a framework to define the prevailing
knowledge gaps and incentives for academia, pest management professionals (PMPs) and public health agencies to participate. Journal of Urban
Ecology, 3(1), jux005, https://doi.org/10.1093/jue/jux005
• Puckett, E.E., Park, J., Combs, M., Blum, M.J., Bryant, J.E., Caccone, A., Costa, F., Deinum, E.E., Esther, A., Himsworth,C.G, Keightley, P.D., Ko, A., Lundqvist,
Å., McElhinney, L.M., Morand, S., Robins, J., Russelll, J., Strand, T.;M., Suarex, O., Yon, L., & Munsi-South, J. (2016). Global population divergence and
admixture of the brown rat (Rattus norvegicus). Proceedings of the Royal Society B: Biological Sciences, 283(1841), 20161762.
https://doi.org/10.1098/rspb.2016.1762
• Purcell, R.H., Engle, R.E., Rood, M.P., Kabrane-Lazizi, Y., Nguyen, H.T., Govindaran, S., St Claire, M., & Emerson, S.U. (2011). Hepatitis E virus in rats, Los
Angeles, California, USA. Emerging Infectious Diseases, 17(12), 2216-2222. https://doi.org/10.3201/eid1712.110482