Keywords

Introduction

Mammalogy is a branch of zoology dealing with mammals. The term blends Mammalia (i.e., mammals) and -logy (from Ancient Greek logos: a principle of knowledge, a reason, or a study). The hairy animals with a chain of three bones in the middle ear, a single bone in the lower jaw which articulates with the squamosal bone, the left aortic arch of the fourth pharyngeal arch, and with cheek-teeth bearing several roots, were known to early naturalists as Theria (from therion, Greek for a wild beast) or Quadrupedia (a combination from quadri, to mean four, and pes for hand, both Latin; i.e., quadrupeds or four-handed). The term Mammalia was coined by Linnaeus in the 10th edition of Systema Naturae (1758), to denote “these and no other animals [which] have mammae [mammata]” (Schiebinger 1993). Mamma (plural is mammae) is a Latin term designating the milk-secreting organs of females and translates either as breast or teat. The term mammalogy (also mammology) therefore literally means “a study of breasts/teats” and not of breast-bearing animals (Schiebinger 1993). The term mastology, which is in use in the Portuguese-speaking World (e.g., Brazil), has identical connotations, meaning a study of mammary glands. Another term was coined by Pallas (1811), a Russian naturalist of German origin, namely, Lactantia (i.e., alluding to breast-feeding).

Mammalogy explores every aspect of structure, function, and natural history of mammals and incorporates diverse aspects of management of wild populations. Usually, mammalogy focuses on free-living mammals, both extant and fossil, but leaves domesticated forms to veterinary medicine and animal husbandry. Scientists who study mammals may be primarily interested in them per se or may utilize these animals as models to understand more general biological principles. Depending on this, students of mammals can identify themselves as mammalogists, or as ecologists, population biologist, behavioral scientists, physiologists, conservationists, morphologists, wildlife managers, paleontologists, evolutionary biologists, and so forth. In consequence, one can trace scientific papers dealing with mammals in a broad spectrum of periodicals, starting from journals which specialize on mammals, to periodicals covering nearly any field of biology.

The diversity and complexity pose problems also to students of the history of mammalogy. We therefore restricted ourselves to the activities focusing on delimitation of mammalian species and documenting mammal faunas. In its narrow sense, these are the fields of taxonomy and zoological nomenclature. These two fields together with descriptive morphology and rudimentary zoogeography formed the beginnings of modern mammalogy.

Europe as a Starting Point

The formal establishment of zoological nomenclature by the Swede Carolus Linnaeus (1707–1778) can be regarded as the starting point of systematic mammal research in Europe (Linnaeus 1758). His work, however, was based on numerous earlier publications by uncounted authors, such as Gessner and Forer (1563), which are not further treated here. Linnaeus named 77 European mammal species (see Table 1), most of which are still valid. The study of mammal taxonomy continues until today. Reasons are the changing techniques such as the study of chromosomes and DNA sequences which allow deeper insight into the speciation process, in different views on delimitation of species, but also the study of the last remaining unexplored spaces in Europe.

Table 1 Preliminary list of recognized mammal species known to occur in Europe as defined by Hackländer and Zachos (this volume) with authors, year, and source. Note that this list is not identical with the eventual list of species chapters in this handbook.
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Most early researchers dealing with mammals came from Europe. The term mammalogy was introduced (as French mammologie) by a French zoologist Anselme-Gaëtan Desmarest (1784–1838) in 1820. In comparison with ornithology, which was in usage already in the sixteenth century, the term mammalogy emerged relatively late and was also hesitantly applied during the nineteenth century when ornithology was already widely used. In the early twentieth century, mammalogy was still only occasionally used in French (e.g., Trouessart 1910) and English (e.g., Barrett-Hamilton 1913). At about that time (1919), the American Society of Mammalogists was founded along with the quarterly Journal of Mammalogy (Hoffmeister and Sterling 1994).

The first professional mammal society in Europe was founded in 1926 as Deutsche Gesellschaft für Säugetierkunde (German Society for Mammalian Biology) with its journal Zeitschrift für Säugetierkunde (since 2001 Mammalian Biology). Mammals have been translated to German as Säugetiere (literary sucking animals) and the science devoted to their study received a name Säugetierkunde (Kunde is German for science). In 1936 the Natural History Museum in Paris started publishing the periodical Mammalia (now published by de Gruyter). In 1954 the Mammal Society was founded in the UK, with a periodical Mammal Review starting in 1970. Mammalogy has been avoided in all these attempts. The first professional mammal society in Europe to adopt the name mammalogy was seemingly the Mammalogical Section of the Natural History Society at the National Museum in Prague in 1958 (In Czech: Mammaliologické sekce Přírodovědeckého sboru Společnosti Národního Musea), together with the periodical of a similarly long name in 1959 (Mammaliologické zprávy/Novitas mammaliologicae. Nová série/Series nova, 1962 renamed as Lynx (n.s.) Praha). The name “mammaliologické” was difficult for pronunciation and several European languages gave priority to theriology. Czechs and Italians, for example, interchangeably used in the past, and still now both, mammalogy and theriology. Thus, the Italian Mammal Society (its official name in English) is called in Italian Associazione Teriologica Italiana and is issuing a periodical with the English title Hystrix: Italian Journal of Mammalogy since 1986.

The term theriology was more widely accepted in eastern Europe which was evident from the periodical Acta Theriologica (since 2015 Mammal Research) issued since 1954 by the Mammal Research Institute of the Polish Academy of Sciences (founded in 1952) and from the professional mammal society founded in the former Soviet Union under the name All Union Theriological Society. The Society involved 12 regional sections and after the collapse of the Soviet Union some of these sections continued their work as independent societies, for example, Russian Theriological Society (since 1992; the official name is Russian Theriological Society of the Russian Academy of Science), Ukrainian Theriological Society (1993), and Lithuanian Theriological Society (1989). The term mammalogy is not in use in these countries, and also the journals published by the societies avoid it: Theriologia Ukrainica (started in 1998 as Proceedings of the Theriological School), Russian Journal of Theriology (founded in 2002), and Theriologia Lituanica (not published continuously).

Other 27 mammalogical journals founded in Europe after the Second World War are listed in Table 2. There are more local leaflets or journals on bats and other organisms with a more local distribution.

Table 2 An overview of mammal journals published by European societies or institutions
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Taxonomy

The discovery of about 320 indigenous and introduced mammal species (Table 1) in Europe took more than 250 years. We list 322 species, but the number of acknowledged species will differ depending on the underlying taxonomic philosophy and species concept(s). As already mentioned, the formal system of nomenclature was developed by C. Linnaeus. His basic works (Linnaeus 1758, 1761, 1766, 1768) listed and named 77 species of mammals from Europe, most of which are currently regarded as valid species. Further new European species of mammals were described by Berkenhout (1769), Laxmann (1769, 1788), Forster (1770), Gmelin (1770, 1778, 1788), Güldenstaedt (1770), Pallas (1769, 1770, 1771, 1773, 1775, 1776, 1777, 1778, 1779, 1811), Pennant (1771), Schreber (1774, 1775, 1777, 1780), Phipps (1774), Müller (1776), Erxleben (1777), Hermann (1779, 1780), Zimmermann (1780), Borowski (1781), Molina (1782), Güldenstaedt and Pallas (1783), Fabricius (1791), Kerr (1792), Borkhausen (1797), Bechstein (1800), Shaw (1801), Lacépède (1804), Sowerby (1804), E. Geoffroy (1803, 1806, 1810, 1811, 1818), Traill (1809), Cuvier (1812, 1823, 1829), Rafinesque (1814), Desmarest (1817), Blainville (1817, 1838, 1839), Kuhl (1817, 1820), Montagu (1821), Savi (1822, 1839), Horsefield (1823), Liechtenstein (1823, 1828), Boie (1825), Leach (1825), Gray (1812, 1828, 1834, 1846, 1874), Lesson (1827, 1828), Temminck (1827, 1838, 1840), Cuvier in Lesson (1828), Millet (1828), Fischer (1829), Meyen (1833), Melchior (1834), Küster (1835), Hodgson (1836), Sviridenko (1936), Sélys-Longchamps (1836, 1838, 1839), Bonaparte (1837, 1840, 1845), Martin (1838), Schinz (1837, 1838), Ogilby (1839), Keyserling and Blasius (1839, 1840), Lereboullet (1842), Nordmann (1840), Blyth (1841), Martins (1842), Lilljeborg (1844), Crespon (1844), Eversmann (1845), Owen (1846, 1866), Sundevall (1846), Blasius (1853), Gervais (1855), Rosenhauer (1856), Brandt (1859), Tomes (1857), Lilljeborg (1861), Bocage (1865), Frivaldszky (1865), Burmeister (1867), Peters (1867, 1869), Mina-Palumbo (1868), Swinhoe (1870), Von Haast (1876), Danford and Alston (1877, 1880), Anderson (1878), Dobson (1878), Gerbe (1879), Poljakov (1881), Petényi (1882), Lataste (1883), Monticelli (1885), Satunin (1895, 1901), Allen (1890), De Winton (1898), Nehring (1894, 1898, 1902), Neumann (1899), Merriam (1900), Miller (1900, 1908, 1910), Thomas (1892, 1901, 1902, 1906), Barrett-Hamilton (1900, 1903, 1907), Matschie (1901), Cabrera (1904, 1907, 1911), Fatio (1905), Bate (1906, 1937), Barrett-Hamilton (1907), Mottaz (1907), Miller (1908, 1910), Satunin (1908, 1909), Mehely (1909), True (1913), Shidlovsky (1919), Martino, V. &. E. (1922), Ognev (1922, 1924, 1935), Turov (1924), Vinogradov (1925), Altobello (1926), Formozov (1931), Martino, V. &. E. (1931), Kormos (1934), Kuzjakin (1935, 1965), Bate (1937), Zubko (1937), Coutourier (1938), Reshetnik (1939), Heinrich (1952), Kratochvíl (1952), Kratochvíl and Rosicky (1952), Wettstein (1927, 1953), Fraser (1956), Lehmann (1961, 1964), König (1962), Malec and Storch (1963), Ondrias (1966), Palacios (1977), Felten (1971, 1977), Djulic (1980), Sokolov, Kowalskaya and Baskevich (1980), Petrov and Ružić (1983), Sokolov, Baskevich and Kowalskaya (1986), Hutterer, López-Jurado, and Vogel (1987), de Paz (1994), Helversen and Heller (2001), Mucedda et al. (2002), Benda et al. (2004), Hulva and Benda (2004), Cucchi et al. (2006), Nicolas, Martínez-Vargas, and Hugot (2017), Kryštufek et al. (2018) and Ruedi et al. (2019). References are given in Table 2. Subspecific names, a possible source for further species names, are not listed here. More species will be recognized after biogeographical studies have been finished, such as for voles (e.g., Jaarola and Searle 2002), or shrews (Amori and Castiglia 2018). See also Burgin et al. (2018) for a discussion of a recent species list and Genovesi et al. (2009) for a review of alien species.

In parallel with the discoveries of new species, mammalogists of the late eighteenth and nineteenth centuries also built up regional lists of species. Progress in cataloguing the mammal richness was not a steady accumulation of knowledge, but rather a series of ups and downs. The nineteenth-century European mammalogy reached its pinnacle in mid-century (1857) in The Natural History of Mammals of Germany and adjacent regions of Central Europe by the German Johann Heinrich Blasius (1809–1870). His work remained in high esteem for the rest of the century on the one hand, but also created an illusion that not much new could be expected in Europe on the other hand. European mammalogists, confronted with the European mammal fauna, which seemed not to be particularly challenging, and the challenges offered by overseas colonial possessions, chose the latter.

In the meantime, mammalogy in the New World progressed rapidly both conceptually and methodologically. Cuvier’s concept of immutable species and varieties was replaced by polytypic species and subspecies. Study of variation emerged as the central topic in mammalogy which demanded clearer and more intelligible diagnostics of taxa. This could not be achieved without detailed descriptions of cranial and dental morphology, in addition to external appearance, and meticulous morphometrics for quantifying size and proportions. Above all, comparisons between taxa necessitated samples (hypodigms), not just individuals, and such demands could no longer be satisfied by taxidermic mounts. A whole series of conspecific individuals had to be sampled in the field, measured, prepared in a standardized way, and deposited in museum collections for further study. A museum voucher became a standard in taxonomic work. It consisted of a skin and skull with attached label containing detailed information on the locality, date of collecting, sex, standard external measurements, and relevant details on the habitat and observations made during dissection. The mammal collections were still small and scrappy in the 1880s and 1890s, and small mammals in particular were heavily underrepresented. At that time, Clinton Hart Merriam (1855–1942) at the United States Department of Agriculture (founded in 1885 and renamed in 1905 to Bureau of Biological Survey) started collecting small mammals using commercially available traps called the “Cyclone.” The trap “was an affair of tin and wire springs, only about two inches square when collapsed, cheap in cost, and easily portable in quantity” (Osgood 1944). Simultaneously, the American mammalogists modified the way of skinning birds as museum vouchers, developed earlier on by ornithologists. Application of these two novelties enlarged mammal collection in the US Museums to proportions which at that time were unprecedented. Still in 1910, Edouard-Louis Trouessart (1842–1927) from the Natural History Museum in Paris wrote with amazement of the US collections in which common species were represented by series numbering up to 1200 museum vouchers (Denys et al. 2012).

In the 1890s Gerrit Smith Miller (1869–1956), at that time still employed at the Department of Agriculture (in 1898 he moved to the United States National Museum) transplanted to Europe “the methods and philosophy of the ‘American School of Mammalogy’, including the systematic study of large series of uniformly prepared small mammal specimens” (Dunnum and Cook 2012). In 1894, when Miller demonstrated at the British Museum new methods of field collecting small mammals using the “Cyclone” traps and processing the material as standard museum vouchers, European mammalogists were deeply impressed. The method was quickly adopted in various European countries, for example, France, Germany, and Russia.

European Mammal Collections

Europe has a long history of biological collections. Collections for scientific purposes (Genoways and Schlitter 1981) are younger and often are subject to change. Only larger collections run by public institutions have a chance to survive for longer periods. Table 3 lists some current collections where mammals are kept for scientific studies and/or for public display. The listed mammal collections sum up to 3.2 million of specimens.

Table 3 European mammal collections containing about 2,000 or more specimens of recent mammals
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European Mammal Societies

After the First and Second World Wars, some national societies for the study and conservation of mammals were founded. One of the earliest ones was founded in Germany (1926), followed by The Netherlands (1952), France (1954), the United Kingdom (1954), Czechoslovakia (1958), Italy (1983), Lithuania (1989), Russia (1992), Ukraine (1993), and Spain (2000). Numerous local societies for the conservation of bats, dormice, hamsters, hedgehogs, large carnivores, otters, etc., were also founded in various European countries.

Mammal Congresses

Scientific congresses on mammalian topics have been held in Germany by the German Society of Mammalogist almost annually since 1926 (Hutterer 2001), in France by the French Society for the Protection of Mammals (13th Colloque International de Mammalogie in Banyuls, 1989), and certainly also by many other national societies. The European Mammal Foundation has held congresses since 1991 (Lisbon), the eighth one being organized in Warsaw in 2019. In 1960 and 1971, early meetings were held in Brno, Czechoslovakia. The International Theriological Congress was first organized in Moscow in 1974 and has been continued under the name International Mammalogical Congress since 2001 (Lidicker 2011).

Handbooks

Despite all the engagements in overseas explorations, several European countries printed mammal faunas of their territories already in the second half of the nineteenth century: UK (Lydekker 1896, Johnston 1903, Barrett-Hamilton 1910–1921, 1913), Germany (Blasius 1857), or Spain (Graells 1897). There was a need, however, for a comprehensive treatise at the continental scale to standardize taxonomy and nomenclature. In 1910, Trouessart, at that time appointed at the Mammals and Birds section of the National Museum of Natural History in Paris (Denys et al. 2012), published the “Fauna of the Mammals of Europe” (Trouessart 1910). Shortly afterwards, an even more influential work followed, authored by Miller. Several mammalogists in London, Lord Lilford (Thomas Littleton Powys, 1833–1896), Oldfield Thomas (1858–1929), and Gerald Edwin Hamilton Barrett-Hamilton (1871–1914) put huge efforts in completing collections of European mammals which around 1910 contained 5000 museum vouchers, including 124 types. This material, along with 4000 vouchers held in Washington, and further 2500 museum specimens scattered across Europe, allowed Miller to produce a monographic treatise, a Catalogue of mammals of “Europe exclusive of Russia” on more than one thousand pages (Miller 1912). Miller recognized 314 “forms” (species and subspecies) in 69 genera. He himself examined museum vouchers of all these forms except six. Miller’s Catalogue was much more than just a list of species. It contained detailed morphological descriptions, accompanied by craniodental measurements and drawings of skulls and dentition, produced by Amedeo John Engel Terzi (1872–1956). The quality of illustrations is such that they are still reproduced in textbooks of mammalogy. Furthermore, the Catalogue included dichotomous keys to families, genera, species and subspecies, and lists of all vouchers examined, together with localities and other details like sex, date, and collector. The Catalogue was a model for the most important contributions to European mammalogy (see Shamel et al. 1954) and served as the taxonomic standard well into the 1970s and 1980s. Even today, the Catalogue remains to be an invaluable nomenclatural source and a reference for morphological data. Contrary to Miller, Trouessart also considered marine mammals and covered Europe in its entirety, that is, as far as the Urals in the east and the Caucasus in the south-east. Despite the broader geographic and taxonomic scope, Trouessart’s book counts only 266 pages (as compared to 1019 pages in Miller’s Catalogue) which was a consequence of less detailed descriptions and lack of illustrations and identification keys. Miller’s Catalogue prevailed because it allowed mammalogists a more secure classification of their vouchers and recognition of still unnamed taxa.

Miller in his Catalogue strictly adhered to Europe west of Russia, an evident consequence of the paucity of material from the East, both in general, and in particular in major museums of Central and West Europe. At about same time, the Russian mammologist Sergey I. Ognev (1886–1951) published “Fauna Mosquensis” which was supported by about 3000 museum vouchers (Bakloushinskaya et al. 2012). Despite such parallel trends in the West and the East, Miller’s geographic scope proved remarkably persistent, being uniformly followed by subsequent authors well into the 1980s. This was not a matter of free choice, but of political reality in Europe during the twentieth century. In the same year that Miller published his Catalogue, a local conflict erupted in the Balkans, mammalogically the least known region in Europe. The skirmish soon became known as the First Balkan War. It was followed in 1913 by a brief Second Balkan War and in 1914 by the Third Balkan War which escaped control and developed into World War I. When the Great War, as it was called at the time, ended, the political map of Europe had been redrawn. The continent was instable, insecure, impoverished, and ideologically divided. Miller’s border became a reality and West and East Europe took their own courses in mammalogy with not much collaboration. The environment therefore did not encourage mammal research and not many syntheses on mammals were published on either side of the border between the two wars.

Mammals were treated in handbooks at different levels. Mammals of the Palaearctic Region were covered by Ellerman and Morrison-Scott (1957, 1966) and Corbet (1978, 1984), and European mammals by Keyserling and Blasius (1840), Schmiedeknecht (1906), Trouessart (1910), Miller (1912), Hainard (1948, 1949), van den Brink (1955), Gaffrey (1961), Corbet (1966), König (1969), Curry-Lindahl (1975), Corbet and Ovenden (1980), Schilling et al. (1983), Bjärvall and Ullström (1986), Görner and Hackethal (1988), and Lange et al. (1994). Niethammer and Krapp (1978–2005) presented the first detailed handbook series, and Macdonald and Barrett (1993) provided an overview of British and European mammals. More recently Macdonald (1995), Dietz et al. (2007), Temple and Terry (2007), Aulagnier et al. (2007), Grimmberger and Rudloff (2009), Twisk et al. (2010), and Dietz and Kiefer (2014; only bats) reviewed the status and distribution of European mammals. Mitchell-Jones et al. (1999) presented an atlas of European mammals as the result of an international cooperation. Temple and Cuttelod (2008) published a review of mammals of the Mediterranean area. Books treating mammals of mainly western Europe at a more local level are listed in Table 4. Wilson and Reeder (2005) and Wilson et al. (2009–2018) are modern checklists or handbooks which also include the European species.

Table 4 Some handbooks and faunal treatments of European mammals
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The mammalogists of eastern Europe, which lived for the major part of the twentieth century within the borders of the Soviet Union (particularly Russia, Belarus, Ukraine, and Moldavia), published uncountable articles and books, often as part of wider geographical treatments. This includes a series of taxonomic compilations of various mammalian groups of Europe and Palaearctic Asia, for example, of insectivores by Gureev (1979) and Zaytsev et al. (2014), a large number of works covering various rodents and lagomorphs which were summarized by Gromov and Erbajeva (1995), carnivorans and ungulates by Heptner and co-workers (e.g., Heptner and Sludskii 1992) which appeared in four volumes and so forth. There were several attempts to compile the entire mammal fauna of the Soviet Union under a single title, for example, by Bobrinskii et al. (1944 and reprinted editions), Gromov et al. (1963, in two volumes), Flint et al. (1965), and Pavlinov et al. (2002). The majority of publications during the Soviet period were in Russian and were therefore not accessible to the majority of mammologist working outside the Soviet Union. Because of their outstanding importance, some were translated into English and the best known in the West were seven volumes of the “Mammals of Eastern Europe and Northern Asia” (later volumes appeared under the title “Mammals of the USSR and Adjacent Countries”) by Ognev published in the Soviet Union during 1928–1950 and released in English from 1962–1966 (Ognev 1962–1966; for references see Bakloushinskaya et al. 2012). Mammals are also covered in a large number of regional works. In the European part of Russia, Stroganov (1949) and Ivanter (2009) wrote about the mammals of Karelia, Estaf’ev (1994, 1998) of the extreme north-eastern European Russia, Vechkanov et al. (2004) about Mordovia, Kruskop (2002) about the Moscow area, Popov (1960) and Schlyakhtin et al. (2009) on the Volga region, Bol’shakov et al. (2000) of the Ural Mts, and so forth. Similarly, Serzhanin (1955 and reprinted editions) and Kozlo (2003) compiled knowledge on the mammals of Belarus, Dulitskiy (2001) about the Crimea, and Migulin (1938), Tatarinov (1956), Mezhzherin and Lashkova (2013), and Abelentsev with co-workers (in three volumes) about the Ukraine (zagorodniuk 2017).

The Discovery of Species

The cumulative number of acknowledged mammalian species in Europe has increased steadily ever since the 1758 Systema Naturae. The cumulative curve was the steepest before 1850, that is, during the period of most intensive naming of new species. Although the pace of new discoveries or descriptions slowed down after 1950, the curve is not yet asymptotic; hence, discoveries of new species are still likely. The curve reflects the development as perceived from the current state of knowledge (Fig. 1). As we already saw, the actual progress was much less directional, and therefore more erratic. In Western Europe, the number of recognized species was the highest in the early twentieth century but reached the lowest point in mid-century in a taxonomic revision by Ellerman and Morrison-Scott (1951). This work, which was at the time celebrated as “a magnificent synthesis … [which] has sweepingly arranged the mammals of Eurasia …” (Mayr 1963), is now denounced as representing a period of “taxonomic inertia” by some which underestimated the species richness, retarded the taxonomic progress in Europe, and in consequence affected biodiversity conservation policies (e.g., Gippoliti and Groves 2018). For a short treatment of different taxonomic philosophies, see Hackländer and Zachos (this volume). In the decades to follow Ellerman and Morrison-Scott (1951), the mammalogists were steadily adding “new” species (Table 1). In many cases they were arguing that taxa which already had valid names but were suppressed as junior synonyms do in fact represent full species. The new persuasive evidence frequently came from cytological laboratories, and later on from molecular evidence. That said, even in the light of new high-resolution molecular data, a large part of the disagreement over species delimitation and species numbers is due to fundamental differences in taxonomic philosophy, that is, which species concept one should follow.

Fig. 1
figure 1

Cumulative number of species of European mammals (dots) as recognized currently since the 1758 publication by Linnaeus. Note that the best-fit curve still does not reach the asymptote. Bars show variation in number of recognized species in Western Europe (i.e., Europe without Russia/Soviet Union) since the revisions of Trouessart (1910) and Miller (1912). Some species have been omitted to make different sources comparable

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Outlook

Today mammalogy is a complex science which is connected to a large set of other disciplines, such as physiology, cytology, ecology, population biology, behavior, conservation, morphology, paleontology, evolutionary biology, and so forth. Many of these fields were not even mentioned in the text. The basic disciplines however are taxonomy and evolution. Although a large amount of progress has been made in the recent past, we are still discovering and sorting species of mammals, also in Europe, attempting to put order into the mammal diversity that we find in nature.