The timing of migrant birds’ arrival on the breeding grounds, or spring arrival, can affect their survival and breeding success. The optimal time for spring arrival involves trade-offs between various factors, including the availability of food and suitable breeding habitat, and the risks of severe weather. Due to climate change, the timing of spring emergence has advanced for many plants and insects which affects the timing of maximum food availability for migratory birds in turn. The degree to which different bird species can adapt to this varies. Understanding the factors that influence spring arrival in different species can help us to predict how they may respond to future changes in climate. This study looked at the variation across space in spring arrival time to Europe for 30 species of birds which winter in Africa. It used citizen science data from EuroBirdPortal, which collates casual birdwatching observations from 31 different European countries, including those submitted via BirdTrack. Using these data, the start, end and duration of spring migration was calculated at a 400 km resolution. The research identified patterns in arrival timing between groups of species, and tested whether these were linked to species traits: foraging strategy, weight, wintering location and length of breeding season. Lastly, it investigated how arrival timing was linked to temperature. The results showed that it takes 1.6 days on average for the leading migratory front to move northwards by 100 km (range: 0.6­­–2.5 days). The birds’ movements broadly tracked vegetation emergence in spring. Arrival timing could be split into two major groupings; species that arrived earlier and least synchronously, in colder temperatures and progressed slowly northward, and species that arrived later, most synchronously and in warmer temperatures, and advanced quickly through Europe. The slow progress of the early-arriving species suggests that temperature limits their northward advance. This group included aerial Insectivores (e.g. Swallow and Swift) and species that winter north of the Sahel (e.g. Chiffchaff and Blackcap). For the late-arriving species, which included species wintering further south, and heavier species (e.g. Red-backed shrike and Golden Oriole), they may need to wait until the wet season in Africa progresses enough for food to be available to them south of the Sahara before they can make the desert crossing. The research demonstrates that thanks to advances in citizen science, it is now possible to study arrival timing at a relatively fine scale across continents for a wide range of species, enabling a much fuller understanding of year-round variation between and within species, the associated trade-offs, and the pressures that species face. This knowledge can help mitigate threats to migrant species. For example, the dates of the start of spring migration could by used by each European country to inform hunting legislation. The approaches used in this work could be applied to other taxa where data are sufficient.

Commonly referred to as the UK Red List for birds, this is the fifth review of the status of birds in the UK, Channel Islands and Isle of Man, published in December 2021 as Birds of Conservation Concern 5 (BOCC5). This updates the last assessment in 2015. Using standardised criteria, experts from a range of bird NGOs, including BTO, assessed 245 species with breeding, passage or wintering populations in the UK and assigned each to the Red, Amber or Green Lists of conservation concern. The same group of experts undertook a parallel exercise to assess the extinction risk of all bird species for Great Britain (the geographical area at which all other taxa are assessed) using the criteria and protocols established globally by the International Union for the Conservation of Nature (IUCN). This resulted in the assessment of 235 regularly occurring species (breeding or wintering or both), the total number assessed differing slightly from BOCC5 due to different rules on the inclusion of scarce breeders and colonisation patterns. The results of this second IUCN assessment (IUCN2) are provided in the same paper as BOCC5. Increasingly at risk This update shows that the UK’s bird species are increasingly at risk, with the Red List growing from 67 to 70. Eleven species were Red-listed for the first time, six due to worsening declines in breeding populations (Greenfinch, Swift, House Martin, Ptarmigan, Purple Sandpiper and Montagu’s Harrier), four due to worsening declines in non-breeding wintering populations (Bewick’s Swan, Goldeneye, Smew and Dunlin) and one (Leach’s Storm-petrel) because it is assessed according to IUCN criteria as Globally Vulnerable, and due to evidence of severe declines since 2000 based on new surveys on St Kilda, which holds more than 90% of the UK’s populations. The evidence for the changes in the other species come from the UK’s key monitoring schemes such as BTO/JNCC/RSPB Breeding Bird Survey (BBS) for terrestrial birds, the BTO/RSPB/JNCC Wetland Bird Survey (WeBS) for wintering populations and the Rare Breeding Bird Panel (RBBP) for scarce breeding species such as Purple Sandpiper. The IUCN assessment resulted in 108 (46%) of regularly occurring species being assessed as threatened with extinction in Great Britain, meaning that their population status was classed as Critically Endangered, Endangered, or Vulnerable, as opposed to Near Threatened or of Least Concern. Of those 108 species, 21 were considered Critically Endangered, 41 Endangered and 46 Vulnerable. There is considerable overlap between the lists but unlike the Red List in BOCC5, IUCN2 highlights the vulnerability of some stable but small and hence vulnerable populations as well as declines in species over much shorter recent time periods, as seen for Chaffinch and Swallow.

This stunning new book brings together the latest research findings, delivered through an accessible and engaging narrative by the BTO's Mike Toms, with the wonderful artwork generated through the BTO/SWLA Flight Lines project. If you have an interest in our summer migrants, then you'll welcome this fantastic opportunity to discover their stories through art and the written word. By pairing artists, storytellers and photojournalists with the researchers and volunteers studying our summer migrants, we are able to tell the stories of our migrant birds, and the work being done to secure a future for them. Includes artwork by SWLA member artists Carry Akroyd, Kim Atkinson, Federico Gemma, Richard Johnson, Szabolcs Kokay, Harriet Mead, Bruce Pearson, Greg Poole, Dafila Scott, Jane Smith, John Threlfall, Esther Tyson, Matt Underwood, Michael Warren, Darren Woodhead and others.