Synurbization - adaptation of animal wildlife to urban development
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Synurbization - adaptation
of animal wildlife to urban development
Maciej Luniak
Abstract
Recent zoology/ecology coined a new term, synurbization, as an analogy to the existing term of
wider meaning – “synanthropization.” Synurbization denotes adjustment of wild animal popula-
tions to specific conditions of urban environment. The new term, was introduced by
theriologists and it is accepted in ornithology as well. The term “urbanization,” in turn, should
be in ecology applied for changes in landscape (or environment) caused by urban development.
The growing and global tendency towards synurbization, observed recently in animal world, is a
response to world-wide expansion of urban development (urbanization). More and more bird and
mammal populations colonize cities, and some of them are in urban conditions much more
successful than in their native natural habitats. In Europe, the best known examples are black-
bird Turdus merula, magpie Pica pica, Hooded crow Corvus corone cornix, kestrel Falco
tinnunculus, red squirrel Sciurus vulgaris, Striped field mouse Apodemus agrarius, rabbit O.
oryctolagus, red fox V. vulpes. In Warsaw, during the past few decades, at least 12 new bird
species and 2 mammal species have colonized areas of high degree of urbanization.
Synurbic populations show several significant ecological and behavioural differences, as
compared with populations of the same species living in their native non-urban habitats. Among
most typical features of synurbization are: higher density of population connected with reduc-
tion of individual (pair, family) territories, reduced migratory behaviour, prolonged breeding
season (even winter broods) and other changes in breeding ecology, prolonged and changed
(sometimes adversed) circadian activity, increased longevity (but worse health parameters!),
changes in diet and in foraging behaviour, increased intraspecific agression, tameness toward
man and various adaptations to human behaviour. All the above adjustments of synurbic
populations seem to be within the range of natural plasticity of the species. The question
concerning possible genetic differences between synurbic and non-urban populations has no
clear answer so far.
The rapid increase of the phenomenon of synurbization, which is observed in recent decades,
shows chances for coexistence between wild animals and our urban civilization. It also shows
possibilities for managing of wildlife in cities. But it does not change the fact, that a world
ecological crisis affects the fauna in cities just as in the animal world as a whole.
INTRODUCTION
Recent decades have seen an increasing tendency for two other terms used in this field: synanthropization
birds and mammals to colonize cities. This phenom- and urbanization. Synanthropization refers to the
enon posed the need for a new term - synurbization, adaptation of animal populations to human-created
which was created by theriologists-ecologists (anthropogenic) conditions in general and urbaniza-
(Andrzejewski et al. 1978; Babiñska-Werka et al. 1979). tion refers to changes in landscape (environment)
It denotes an adjustment animal populations to caused by urban development. Therefore,
specific conditions of the urban environment, in synurbization is the particular case of
connection with regular existence (often breeding) synanthropization under the specific conditions of
there in the wild state. The term is not applied to urbanization.
individual animals which have come (or been brought The phenomenon of synurbization has been de-
by humans) to an urban area accidentally and which scribed mainly for birds and mammals, but it is
live there for a limited time. Synurbization is related to known also in other animal groups (e.g. amphibians).
Author’s address: Institute of Zoology, Wilcza 64, Pl 00-079, Warszawa,Poland
50 Proceedings 4th International Urban Wildlife Symposium. Shaw et al., Eds. 2004It is a subject of increasing interest to science, because it TAKING UP A FREE ECOLOGICAL
demonstrates ecological and behavioral plasticity and
microevolutionary changes in animal populations NICHE
under anthropogenic pressure. It is also a point of Synurbization is a wildlife response to global
interest in applied ecology, because it implies the expansion of urbanization. The majority of contempo-
possibility of enriching and managing urban wildlife. rary fauna species shaped their ecological and behav-
This paper presents characteristic features of ioral status during the last 1 to 500 million years, while
synurbic populations. Eusynanthropic species living in urbanization, in the scale of landscapes, has occurred
cities - e.g. the house sparrow (Passer domesticus), only during the last 100-200 years. In terms of nature,
house mouse (Mus musculus), brown rat (Rattus cities are “explosion” of new and “strange” type of
norvegicus) and feral pigeon (Columba livia f.urbana) - environments (complex of habitats, landscape)
will be not considered here, as they are not compa- characterized by the highest anthropogenic pressure.
rable with rural populations. Among general reviews Urban development destroys natural habitats, but also
on the topic are those of Gliwicz et al. (1994) and creates new, free ecological niches covering areas
Luniak (1996). which grow rapidly. This expanding “ecological
vacuum” attracts more and more animal populations.
Some of them overcome the ecological barriers posed
THE PHENOMENON by urbanization and adapt successfully to specific
More and more bird and mammal species, repre- conditions offered by the new niche.
sented by growing numbers of local populations, are Among the main pre-requisites for synurbization
settling and increasing their abundance in cities. In are general ecological, demographic and behavioral
Warsaw (Poland), at least a dozen bird species (Table plasticity, particularly a wide spectrum of habitat and
1), and 2 mammal species (the rabbit - Oryctolagus diet requirements.
oryctolagus and the striped field mouse - Apodemus In European fauna, the best-known example of the
agrarius), have colonized highly urbanized areas since expansion of synurbic populations to cities is the
the middle of the century. Examples of synurbization European blackbird (Turdus merula) (Luniak et al.,
of mammals in European cities are provided by the 1990). This species used to be entirely a forest bird, but
squirrel (Sciurus vulgaris, S. carolinensis), the rabbit, the it began to colonize urban parks in western regions of
striped field mouse, the red fox (Vulpes vulpes), the Germany in the first decades of 19th century (in
stone marten (Martes foina), and the badger (Meles Bromberg - 1820, Augsburg - 1830, Frankfurt/M. and
meles). Processes of synurbization also concern wild Stuttgart - about 1850). The expansion continued, and
populations of birds introduced (or reintroduced) to at the beginning of 20th century, it reached western
cities by man. The best known example is the per- territories of present Poland (Gdañsk, Poznañ, Silesia).
egrine falcon (Falco peregrinus), which has been By the middle of the century it reached the line
successfully introduced, in the last two decades, to Kaliningrad - Warsaw - Brno - Sofia. Recently the
cities in North America and in Germany, as well as northeastern range of the urban blackbird population
Prague, Warsaw and Moscow. Introduction of the includes Oslo, Helsinki, St. Petersburg (Russia), Kiev
peregrine into cities has supported the natural recov- and Poltava (Ukraine). At the same time, the
ery of the overall population of this species. Urban synurbization of Asiatic subspecies of the blackbird is
populations of peregrines on both continents have being observed. Turdus merula aterrimus has begun to
increased rapidly and are now much bigger than ever. settle in towns in Turkey (Istanbul, Ankara) and in the
New York and Berlin have the highest concentration of Caucasus (Yerevan, Tbilisi, Cherkesk), while
peregrine falcons in the world. T.m.intermedius is colonizing cities in Kazakhstan
The phenomenon discussed also concerns feralized (Alma-Ata, Samarkand, Tashkent). The synurbic
populations originating from escaped or released cage population of the blackbird has not yet occupied areas
birds. Among the birds which have the most stabile of the northeastern range of the species being as yet
wild populations in several European cities are the absent in Moscow. Blackbirds are common in the
Mandarin duck (Aix galericulata), Canada goose region. Nevertheless the speed and spatial range of the
(Branta canadensis), ring-necked parrakeet (Psittacula expansion of synurbic blackbirds are comparable with
crameri) and common myna (Acridotheres tristis). The the most intensive zoogeographic expansions noted in
possible scale of this phenomenon is shown by data vertebrates - like the collared dove (Streptopelia
from Tokyo and its vicinity, where 71 feral bird species decaocto) and muskrat (Ondatra zibethica) in Europe, or
were reported in the period 1961-1981, 20 of them the house sparrow (Passer domesticus) and starling
breeding in the wild (Narasue and Obara 1982). It is (Sturnus vulgaris) in North America. In all cases
expected that the significance of this factor to urban known, the natural colonization of new towns by the
avifauna will increase in the future. blackbird was firstly by wintering birds, which then
stayed for breeding. Big cities were usually inhabited
Proceedings 4th International Urban Wildlife Symposium. Shaw et al., Eds. 2004 51by the blackbird earlier than small towns in the region. sedentary life and favorable microclimatic conditions. Examples of the rate of growth of synurbic popula- More time in the phenological cycle is left for breed- tions are magpie (Pica pica) and fieldfare (Turdus ing, the physical condition of individuals after winter- pilaris) in Warsaw. The magpie (Luniak et al. 1997) was ing is better and some breeding sites (e.g. in buildings practically absent from the inner city until the 1950s, and other technical objects) are warmed or well and only a few pairs bred there at the beginning of sheltered against the cold. Synurbic blackbirds begin 1960s. In the 1970s, the estimation was 50-200 breed- breeding 1-4 weeks earlier than rural ones, and their ing pairs, and in the 1980s, an increase to 800-1200 last fledglings leave the nest about one month later in pairs breeding was recorded in a 52 sq. km plot in the the summer. Blackbirds in cities usually have 2-3 inner city. In 1990s, the growth of population contin- broods, while those in forests have 1-2. Cases of winter ued. In three decades the magpie achieved the sub- broods among several bird species (e.g. blackbird, dominant position (2%) in the overall bird community collared dove, coot) have been observed in cities. in the highly urbanized areas of Warsaw. Fieldfares Urban magpies in Western Poland build their nests 3-4 began to breed in urban parks of inner Warsaw in 1975 weeks earlier than rural ones, occasionally in winter (
tend to locate their nests higher up than rural ones. In imprinting plays an important role in adjustments,
blackbirds the mean difference is about 1 m. Mallards which make synurbic populations different from rural
of inner Warsaw nest only in tree cavities and in other ones.
elevated sites (eg. baskets on trees), never on the
ground, as rural Mallards commonly do. CHANCE FOR URBAN WILDLIFE
- Changes in feeding behavior. A city offers rich The main consequence of urban development for
resources of anthropogenic food (refuse, feeding by wildlife is a decrease in its species and ecological
people), which are attractive to many bird and mam- diversity. The growing tendency towards
mal species. For some, (e.g., feral pigeon, house synurbization observed recently in birds and mam-
sparrow, collared dove, mallard, corvids, gulls) this mals is an optimistic chance for enriching diversity of
kind of food is a substantial (sometimes the main) urban wildlife. But, increasing synurbization processes
component of the diet, particularly in the winter. The do not change the fact that a global ecological crisis is
feeding behavior of these birds, as well as of some affecting urban fauna, particularly its diversity, as well
mammals (e.g. park squirrels and mice, urban red as the whole animal world. Two examples:
foxes) is adjusted to human customs and is aimed at 1) In the inner area of Warsaw, 47 bird species have
finding or receiving human food. decreased populations or vanished since the middle of
- Tameness toward people. This is the basic barrier century. In the same period, 34 species (Table 1) have
to be crossed by vertebrates under synurbization, increased their populations in this area, as a result of
because coexistence with man is the condition for synurbization and often in connection with expansion
successful inhabiting of the city. Almost all bird and of the geographic range of the species (data of W.
mammal species living there reduce their escape Nowicki). The overall avifaunal diversity of inner
distance in comparison to that maintained in rural Warsaw decreased, despite of the intensive
areas. They often follow people begging for food, or synurbization processes shown by several species.
even sit on people. Many examples show that species 2) In Berlin, among 170 breeding bird species
which in natural circumstances are particularly shy recorded, 97 (57%) are included in the Red List, of
towards man (e.g., raptors, waterfowl hunted by man) which 29 (17%) have become extinct, and 40 (23%) are
become tame in cities. Jedraszko-Dabrowska (1990) threatened by extinction or highly endangered (Witt
described aggressive reactions to man in urban coots. 1991).
Such behavior is never observed in rural populations Synurbization of some species could cause practical
of this species. problems when their populations grow to high
- Increased intra-specific aggression is observed in concentrations. Such problems cause roosting of
synurbic populations, a tendency connected with the starlings (Sturnus vulgaris) and corvid birds (Corvidae)
high density of individual territories and spatial in cities. Winter roosting concentration of rooks (Corvus
limitations. Such behavior is commonly observed in frugilegus) and other corvids in Warsaw were esti-
urban blackbirds, and it was also described by mated at approximately 250 thousand of birds (Luniak
Jedraszko-Dabrowska (1990) in the coot. Laboratory 1990), and in Moscow, approximately 800,000 (Ilychev
tests have also revealed that urban blackbirds have et al. 1987). An example of such problems is the
better learning capability that forest ones (Walasz Canada goose in North American cities.
1990). Current scientific knowledge, and practical experi-
The question regarding the extent to which synurbic ences, offer wide range of possibilities to stimulate,
populations have their own genetic identity is still not and to control synurbization processes. Cities could be
clearly solved. Changes in ecological parameters and refugee and conservation areas for some endangered
behavior can be explained by the direct effect of urban species. A spectacular example of this is recovery is the
conditions and seem to be within the range of the peregrine falcon. Successful recovery in North America
species’ natural plasticity. Nevertheless, morphologi- and Europe of this nearly extinct bird is connected
cal, anatomical and physiological differences between with rapid growth of its urban population. In this case
urban and rural populations of the striped field mouse synurbization of peregrine was stimulated by intro-
have been found and interpreted as genetic (Gliwicz duction of this species in many cities and protection
1980, Gliwicz et al. 1990). Such differentiation was also measures taken there.
found in the behavior of blackbirds of urban and forest Managing urban wildlife by stimulation and
origin reared in the laboratory (Walasz 1990), and also control of synurbization processes should be aimed
in studies by Schwabl et al. (1985) and Berthold (1984) to support natural functions and structure of the city
on conditioning of migratory behavior in birds. Septon ecosystem, with ecological and social needs of man
et al. (1995) found that in Midwestern North America, and with the general strategy of nature conservation
90% of peregrine falcons of identified urban origin in mind.
nest in cities, while 83% of peregrines reared in natural
habitats on cliffs nest in such sites. It seems that
Proceedings 4th International Urban Wildlife Symposium. Shaw et al., Eds. 2004 53CONCLUSIONS Ilyichev, V. D., B. T. Butyev, and M. B. Konstantinov.
1987. Birds of Moscow and its vicinity. Izd. Nauka,
The term “synurbization” denotes more precisely
Moskva.
the phenomenon of the adjustment of animal
Jerzak, L. 1995. Breeding ecology of an urban Magpie
populations to the urban environment than the term Pica pica population in Zielona Góra (SW Poland). Acta
“urbanization,” which should be applied to changes orn. 29: 123-133.
in the landscape caused by urban development. Jedraszko-Dabrowska, D. 1990. Specific features of an
The synurbization of bird and mammal popula- urban lake bird community (case of the
tions is an increasing phenomenon worldwide. It is Czerniakowskie Lake in Warsaw). In: Luniak, M. (ed.),
a response of wildlife to the global explosion of Urban ecological studies in Central and Eastern
urbanization, which creates new ecological niches Europe. Ossolineum, Wroclaw, pp. 167-181.
acceptable to some animal species. Synurbic popula- Lidauer, R. M. 1983. Knochenfrakturen bei Stadtamseln
tions are distinguished from rural ones in relation to (Turdus merula). Oekol. Voegel 5: 111-126.
several specific ecological and behavioral features. In Luniak, M. 1996. Synurbization of animals as an factor
some cases morphological, physiological and parasito- increasing diversity of urban fauna. In: di Castri, F.,
logical differences between urban and non-urban and T. Younes (eds.). Biodiversity, science and develop-
populations were revealed. These adaptations seem to ment: towards a new partnership. CAB International,
be within the biological plasticity range of the species. pp. 566-575.
Imprinting probably plays an important role in Luniak, M., P. Kozlowski and W.Nowicki. 1997. Magpie
synurbic adjustments. But, evidence was also found Pica pica in Warsaw abundance, distribution and
suggesting genetic differences distinguishing urban changes in its population. Acta orn. 32: 77-87.
populations. Luniak, M., R. Mulsow and K. Walasz 1990. Urbaniza-
The increasing phenomenon of synurbization shows tion of the European Blackbird expansion and adapta-
that there are chances for some kind of coexistence tions of urban population. In: Luniak M. (ed.), Urban
ecological studies in Central and Eastern Europe.
between nature and expansion of urban civilization. It
Ossolineum, Wroclaw, pp. 87-199.
does not, however, change the fact that an ecological
Mac Donald, D. W., and M. T. Newdick 1982. The
crisis is affecting the fauna in cities just as in the animal
distribution and ecology of foxes, Vulpes vulpes (L.) in
world as a whole. Present knowledge offers possibili- urban areas. In: Bornkamm, R., J. A. Lee, and M. R. D.
ties for enriching poor diversity of wildlife in cities, Seaward (eds.). Urban ecology. Oxford Univ. Press,
and to manage it with city dwellers’ needs and general Oxford, pp. 123-138.
strategy of nature conservation in mind. Narasue, M., and H. Obara 1982. Feralization of cage
birds, in and around Tokyo. In: Numata, M. (ed.).
REFERENCES Chiba Bay-Coast Project, IV, Tokyo, pp. 82-86.
Andrzejewski, R., J. Babiñska-Werka, J. Gliwicz and J. Rewkiewicz-Dziarska, A., Wielopolska , A. and J. GilJ.
Goszczyñski. 1978. Synurbization processes in an 1977. Hematological indices of Apodemus agrarius
urban population of Apodemus agrarius. I. Characteris- (Pallas 1771) from different urban environments. Bull.
tics ofpopulation in urbanization gradient. Acta theriol. Acad. Pol. Sci., 25: 261-268.
23: 341-358. Septon, G., J. B. Marks, and T. Ellestad. 1995. A prelimi-
Avilova, I.V., B. B. Korbut, and S. Ju. FOKIN. 1994. nary assessment of Peregrine Falcon Falco peregrinus
[Urbanized population of waterfowl (Anas recovery in Midwestern North America. Acta orn. 30:
platyrhynchos) of the Moscow city]. Izd. Mosk. Univ., 65-68.
Moskva. Schwabl, H., J. C. Wingfield, and D. S. Farner 1985.
Babiñska-Werka, J., J. Gliwicz, and J. Goszczyñski. 1979. Influence of winter on endocrine state and behaviour
Synurbization processes in an urban population of in European Blackbirds (Turdus merula). Z. Tierpsychol.
Apodemus agrarius. II. Habitats of the Striped Field 68: 244-252.
Mouse in town. Acta theriol. 26: 405-415. Tomialojc, L. 1976. The urban population of the wood
Berthold, P. 1984. The control of partial migration in pigeon Colubma palumbus Linneaus 1758 in Europe - its
birds: a review. Ring 10: 253-265. origin, increase and distribution. Acta zool. cracov. 21:
Engel, J., M. Keller, J. Leszkiewicz, and J. Zawadzki. 1988. 586-631.
Synurbization of the mallard Anas platyrhynchos in Tomialojc, L. 1978. The impact of predation on urban
Warsaw. Acta orn. 24: 9-28. and rural wood
Gliwicz, J. 1980. [Ecological aspects of synurbization of pigeon (Columba palumbus) populations. Polish ecol.
Striped Field Mouse Apodemus agrarius (Pall.)]. Studies 5: 141-220.
Wiadomoœci Ekol. 26: 185-196. Walasz, K. 1990. Experimental investigations on the
Gliwicz, J., J. Goszczyñski, and M. Luniak 1994. Charac- differences between urban and forest blackbirds. Acta
teristic features of animal populations under zool. cracov. 33: 235-271.
synurbization - the case of the Blackbird and of the Witt, K. 1991. Rote Liste der Brutvoegel in Berlin, 1.
Striped Field Mouse. Memorabilia zool. 49: 237-244. Fassung. Berl. Ornithol.
54 Proceedings 4th International Urban Wildlife Symposium. Shaw et al., Eds. 2004Table 1. Examples of bird species which have colonized Warsaw recently, as a result of their synurbization
(not as a geographical expansion). * - non-breeding species.
Table 2.Examples of differences in density of populations - rural versus urban ones. PL - data from Poland, x -
multiplication.
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