Underrated, unappreciated and unloved habitats: their unquestionable significance

The United Nations designated the first Monday of October of every year as World Habitat Day to reflect on the state of our towns and cities, and on the basic right of all to adequate shelter. The Day is also intended to remind the world that we all have the power and the responsibility to shape the future of our cities and towns.

The day marks the commencement of a month’s worth of activities, events and discussions on urban sustainability. In light of this event, I wanted to celebrate a handful of habitat types which I perceive to be underrepresented and undervalued in the modern world, which undoubtably play an important role in ecosystem function.

The sky

The sky is present above the heads of each and every one of us. But how often do we acknowledge it, let alone consider it’s value to biodiversity?

The open sky harbours a variety of opportunities for a wealth of different species. Although invisible to us, it is a swirling mixture of warm and cool air, headwinds and tailwinds, mist, fog, clouds, rain, light, magnetic fields, the list goes on.

In other words, air is habitat. But it’s only recently that conservation scientists - after years of cataloguing the earth and ocean into ever-finer habitat types - have begun to consider it as such.

The sky is vital for the hunting activities for airborne birds, such as swooping swallows and skydiving swifts. It also is essential for the twice-yearly migration voyage undertaken by many other birds, including those that seem positively earthbound, like fieldfares. Further, it plays a hugely important role in the hunting and migration activities of numerous species of bats.

Recent exciting studies suggest that birds actually seek out helpful winds to their advantage. They can effectively double their distance travelled by selecting the correct height layer within the sky; determining the difference between arriving early to get first pick of breeding territories or showing up late and being stuck with leftovers. For a female, it could affect how much energy she has left for laying eggs.

Overall, the sky provides vital habitat for a breadth of species, creates a strong evolutionary pressure and has shaped migration, hunting techniques, breeding patterns, and population distributions across the world.

Gardens

The potential value of residential gardens for biodiversity conservation should not be overlooked. These habitats comprise a major component of the total greenspace within urban areas and offer substantial opportunities for wildlife. Furthermore, gardens often comprise structurally complex and diverse habitats and offer numerous resources that can be used by multiple taxa, including our much-loved hedgehog.

One study (Van Helden et al., 2020) found that gardens support a similar diversity of native mammals as urban remnant vegetation and that the presence, abundance and reproductive activity for most native mammals was similar in both.

Given that novel urban ecosystems will continue to expand, inclusion of gardens in conservation management is likely to play a role in urban environments.

However small they may be, residential gardens represent an important opportunity for wildlife conservation.

Scrub

Scrub- also known as thickets, or bushy tangled masses of vegetation- doesn’t seem to offer much to humans in terms of aesthetic value. They lack the classic beauty of ancient woodlands, wildflower meadows, or dramatic mountainous landscapes.

However, scientists agree that scrub is actually one of the most critical habitats on offer, and one on which many species depend for their survival! Nationally, there are over 450 rare and threatened species of plant, insect and bird which are associated with this habitat.

Scrub and the surrounding areas provide shelter, mating areas, basking sites, food such as nectar and pollen, nesting habitats and overwintering sites for many species of invertebrate including bees, ants, spiders, wasps, aphids, gall mites and butterflies. For example, the blue carpenter bee nests within the cut ends of bramble stems!

Many species of mammal use scrub habitat to their advantage, for shelter, protection from predators and as a food source. Hazel Dormice (a European Protected Species) feed on nectar and fruit, other shrews and rodents feed on insects, and bats also favour a woodland/scrub edge habitat for midnight hunting.

Almost forty species in Britain listed as birds of conservation concern use scrub habitat! These include yellowhammer, corn bunting, song thrush, turtle dove, linnet, nightjar, tree sparrow, and nightingale, to name a few. These birds depend on scrub for nesting, shelter, and as an easy feeding point for all the invertebrates and berries which are abundant here.

For reptiles, it is the physical structure of scrub which is particularly important. Reptiles are ectothermic (regulate their body temperature by using the external environment) and scrub can provide a source of sheltered sunspots with nearby cover from predatory birds and mammals, perfect for warming up in the mornings! Both reptiles and amphibians also use scrub for refuges, overnight shelter and hibernation sites, not to mention easy access to prey such as invertebrates, molluscs and small mammals which thrive here.

Roofs

House sparrows, starlings, house martins, swifts, feral pigeons, swallows, jackdaws and even barn owls are amongst many other roosting birds which will all use a roof as a home.

Additionally, all 18 of our UK native bat species have been known to roost in buildings, partially due to lack of natural roosting opportunities in mature trees. In this case, and in the case of house martins and swifts which are also almost completely dependent on roofs, we have a responsibility to acknowledge and protect these habitats.

The roofs of older buildings are much more popular with nesting birds, but even in new homes where modern techniques and materials prevent them from getting in, there are still things we can do to attract and give a home to roof-dwelling wildlife. This is ever-more important as older buildings get demolished and established roof habitats disappear.

See here for advice on how you can make your roofs nature friendly.

References:

Van Helden B.E. et al. (2020) An underrated habitat: Residential gardens support similar mammal assemblages to urban remnant vegetation. Biological Conservation, Volume 250