**3. Past and present of Bulgarian owls**

Species of both families, present in the Western Palearctic [6], have been recorded in the fossil (Pleistocene) and subfossil and recent (Holocene) avifauna of Bulgaria.

### **3.1 Tytonidae Ridgway, 1914**

### *3.1.1 Barn Owl (Tyto alba (Scopoli, 1769))*

Fossil/subfossil record: None.

Subspecies: *Tyto alba alba* (Scopoli, 1769) and *Tyto alba guttata* Brehm, 1931 [7]. Residence status: (*T. a. alba*): wintering [7], wintering, breeding [10]; (*T. a. guttata*): resident, vagrant, breeding, migratory [7].

Population number: (*T. a. alba*): no data; single pairs (*T. a. guttata*): 1500–1700 pairs [11], 500–1000 pairs [12], 600 pairs [10].

Conservation status: (*T. a. alba*): protected [12], vulnerable [10]; (*T. a. guttata*): protected [12], vulnerable [10].

Peculiarities: Both European subspecies are spread in the country.

### **3.2 Strigidae Wagler, 1830**

*3.2.1 Eurasian Pygmy Owl Glaucidium passerinum (Linnaeus, 1758)*

Fossil/subfossil record: UP: [13–15]. The find from the Devetashka Cave is the fifth World fossil record of this species [13].

*Owls (Strigiformes Wagler, 1830) in Bulgaria: Past and Present (A Review of the Fossil Record… DOI: http://dx.doi.org/10.5772/intechopen.107371*

Subspecies: *Glaucidium passerinum passerinum* (Linnaeus, 1758) [7]. Residence status: resident, breeding [7, 12].

Population number: 100–120 pairs [11], 30–120 pairs [12], 150–200 pairs [16]. Conservation status: threatened [12], endangered [10].

Peculiarities: The southern border of the breeding range of the species passes through the territory of the country. Bulgarian populations are refugial montane and inhabit old-growth prime coniferous forests [17, 18]. The largest compact prime habitat on the Balkan Peninsula is preserved in the Rhodopes Mnts. [19].

### *3.2.2 Little Owl (Athene noctua (Scopoli, 1769))*

Fossil/subfossil record: UP, GR, NO, ME: [1, 2, 14, 15, 20–23]. Subspecies: *Athene noctua indigena* Brehm, 1855 [7]. Residence status: resident, wintering, vagrant, breeding [7, 12]. Population number: 16,000–18,000 pairs [11], 7500–10,000 pairs [12]. Conservation status: protected [12].

Peculiarities: 90% of the Bulgarian Little owls breed and winter in human settlements [24].

#### *3.2.3 Athene F. Boie, 1822 sp.*

Fossil/subfossil record: GE: [25–27]. This is the oldest record of a strigiform bird in Bulgaria. It is dated ca. 2.5 Mya. The only find (incomplete sternum) came from the Early Pleistocene (Middle Villafranchian, MN 17) locality near Dolno Ozirovo village (Montana Region; NW Bulgaria), known as Varshets locality. The find is evaluated as the oldest so far European record of that genus in Europe [28].

#### *3.2.4 Boreal (Tengmalm's) Owl (Aegolius funereus (Linnaeus, 1758))*

Fossil/subfossil record: UP, ME: [14, 15]. Subspecies: *Aegolius funereus funereus* (Linnaeus, 1758) [7]. Residence status: resident, vagrant, breeding [7, 12]. Population number: 1100–1200 pairs [11], 600–900 pairs [12]. Conservation status: vulnerable [10, 12].

Peculiarities: The Pleistocene locality of the species in the Devetashka Cave falls outside the modern breeding range. The southern border of the breeding range of the species passes through the territory of Bulgaria and Greece. Bulgarian populations are refugial montane and inhabit old-growth prime coniferous forests [17, 18]. The largest compact prime habitat on the Balkan Peninsula is preserved in the Rhodopes Mnts. [19].

### *3.2.5 Eurasian scops owl (Otus scops (Linnaeus, 1758))*

Fossil/subfossil record: UP, GR, NO: [13, 23, 29, 30]. Subspecies: *Otus scops scops* (Linnaeus, 1758) [7]. Residence status: breeding, migratory [7]. Population number: 12,000–14,000 pairs [11], 6000–9000 pairs [12]. Conservation status: protected [12]. Peculiarities: Some individuals winter in the country [31]. A singing male recorded

on 12.02.2014 in a park in Sofia City [32].

*3.2.6 Long-eared Owl (Asio otus (Linnaeus, 1758))*

Fossil/subfossil record: UP, GR, NO, ME: [13, 23, 29, 33]. Subspecies: *Asio otus otus* (Linnaeus, 1758) [7]. Residence status: wintering, breeding [7, 12]. Population number: 12,000–14,000 pairs [11], 3000–5000 pairs [12]. Conservation status: protected [12].

Peculiarities: In winter, migratory specimens from the north form numerous aggregations in forest areas in the country, where they usually stay for several weeks during the coldest periods.
