A total of 98 species were recorded, detailed in Annex 1. All of them are breeding species in the area. The distribution map and the habitats used by each species are included in the section Species Index.

The most widely distributed or most common species, according to the number of grid squares and in order of importance, are: common chaffinch, coal tit, European robin, rock bunting, dunnock, Eurasian wren, crested tit, and Eurasian blackcap. These eight species are present in more than 35% of the grid squares within the study area. In addition to these, three major groups can be identified:

• More or less common species (21), present in 15% to 50% of the grid squares (Annex 1): rock bunting, dunnock, Eurasian wren, crested tit, Eurasian blackcap, short-toed treecreeper, firecrest, woodlark, griffon vulture, mistle thrush, common blackbird, skylark, European stonechat, western Bonelli’s warbler, common wood pigeon, Eurasian jay, common cuckoo, cinereous vulture, northern wheatear, common raven, and great tit.

• Uncommon species (19), present in only 5% to 15% of the grid squares (Annex 1): great spotted woodpecker, goldcrest, common linnet, ortolan bunting, carrion crow, black redstart, Eurasian nuthatch, red crossbill, Eurasian blue tit, European serin, western subalpine warbler, long-tailed tit, western Orphean warbler, tawny pipit, common chiffchaff, common whitethroat, booted eagle, Dartford warbler, and common rock thrush.

• Very localised species (55), present in less than 5% of the grid squares (Annex 1): water pipit, common nightingale, garden warbler, pied flycatcher, red-legged partridge, Iberian green woodpecker, red-billed chough, citril finch, common buzzard, blue rock thrush, common swift, red kite, bluethroat, common quail, crag martin, tree pipit, Sardinian warbler, melodious warbler, grey wagtail, scrub warbler, cirl bunting, red-backed shrike, Iberian magpie, song thrush, European goldfinch, spotless starling, golden eagle, black kite, European nightjar, red-rumped swallow, northern goshawk, Eurasian sparrowhawk, corn bunting, European greenfinch, rock sparrow, house sparrow, common kestrel, white wagtail, great grey shrike, Eurasian hoopoe, short-toed snake eagle, Thekla’s lark, barn swallow, western yellow wagtail, Eurasian golden oriole, peregrine falcon, European honey-buzzard, Bonelli’s eagle, hawfinch, woodchat shrike, spotted flycatcher, Spanish imperial eagle, white-throated dipper, Eurasian magpie, and European turtle dove.

In addition to the species recorded with signs of breeding, other species were also identified that are considered migratory or incidental observations, given the mobility of this group of fauna, which can result in sightings of dispersed individuals of almost any species anywhere. These include: common house martin, common redstart, willow warbler, greater short-toed lark, Eurasian collared dove, and brambling.

Species inventory by UTM 1×1 km grid

The number of species present in each grid square represents the specific richness per area in the park, or the species richness of each individual square. The 1×1 km grid squares shown in dark colours in Figure 1 represent the areas with the highest species richness in the national park.

The grid squares with the highest number of species (more than 20 recorded species) are distributed across different zones of the park, following patches of vegetation with greater diversity and more varied environments. Areas with lower species richness correspond to higher altitudes with little or no vegetation. Notable areas with higher diversity include the oak forests on the slopes extending above the village of Rascafría and the pine forests on both sides of the Navafría pass. Higher-richness areas also occur on the Morcuera slope towards Rascafría, the area known as El Pinganillo, and especially Las Hoyuelas (Figures 1, 2, and 3). Equally notable are the species-rich areas of the Hueco de San Blas and the southern slopes of Morcuera. The species found in these forested areas constitute typical mountain forest communities, including birds native to the predominant pine forest, as well as species from mixed forests, oak woods, and shrublands where these formations occur.

Most of the grid squares with a low number of species (1 to 5), and a large proportion of those with few species (6 to 10) are located mainly in the highest areas, that is, the peaks of the National Park, and in rocky slopes with little vegetation. These areas correspond to zones dominated by rocky habitats, high mountain grasslands, and broom scrub. In these habitats, species richness and bird abundance decline markedly, although broom scrub areas can host high densities of birds during the breeding season, with skylarks, dunnocks, and European stonechats being the main representatives.

A group of species consistently present within the park boundaries are the birds of prey. The colonies of cinereous vulture in Rascafría and La Pedriza, along with the small colonies of griffon vulture distributed across various rocky areas of the mountains, contribute a significant number of individuals, and their ease of detection means that visitors are almost constantly observing large birds in the park. Other birds of prey in higher threat categories, such as the Spanish imperial eagle or Bonelli’s eagle, are represented much more sparsely.

The presence of rare and striking species such as the common rock thrush and the bluethroat is also notable. Some species that used to be more abundant, although detected during this atlas’ fieldwork, are now in decline and scarcely represented; this is the case of the alpine accentor.