The breeding grounds of the North Atlantic population of Sandwich Tern Thalasseus sandvicensis range along the coasts of western Europe and in the Baltic Sea: predominantly in the Netherlands, UK, France, Germany, and Denmark, with a smaller fraction of the population breeding in southern Sweden. This population has fluctuated strongly in size in recent decades due to human activities, pollution, changing availability of food, and outbreaks of highly pathogenic avian influenza. To evaluate whether management actions to further protect the species are needed in Sweden, better knowledge about the recent development of the breeding population is required. We found that the total number of breeding pairs in Sweden between 2007 and 2014 fluctuated between c. 390 and c. 570 pairs. Later, the number increased markedly from c. 630 pairs in 2015 to c. 1,830 pairs in 2021. In 2022 and 2023, the number decreased partly due to avian influenza outbreaks and c. 1,540 pairs bred in 2023. Most pairs bred in the provinces of Blekinge, Gotland, and Skåne. The four largest colonies hosted c. 55% of the cumulative number of breeding pairs between 2007 and 2023. This aggregated distribution makes the species vulnerable to various threats.

We tested for airborne epimeletic (care-giving) behaviour in Common Swift Apus apus towards young swifts during their first flight. Tests were performed where colonies of Common Swift and Western House Martin Delichon urbicum co-occur. Three variants of a flying dummy were used; two with pointed wings of which one entirely black (1) and one with partly white body (2). The third was black with broad wings (3). Reactions were documented on film. Swifts and martins had opposite reactions to dummies 1 and 2. As we anticipated, martins seemed supportive in a test with dummy 2 and seemed to “guide” the dummy epimeletically. However, a swift approached dummy 2 in a support-like attempt, but deviated after a close look. In a test with dummy 3, swifts acted highly hostilely. We discuss reasons for these outcomes and the importance of dummy appearance. We illustrate the flight paths of the dummy, swifts and martins with trajectories, and the behaviour of the Western House Martin is shown in stepwise larger magnification stills of a video.

We investigated the occupancy of alternative breeding pools for Red-throated Loon Gavia stellata and the reproductive output in relation to a selection of habitat characteristics in a coniferous forest inland area in South-central Sweden, using generalized linear mixed models. Models provided good support for the conclusion that small-sized pools with high coverage of floating vegetation were preferred. The survival of pre-fledged chicks was higher when foraging waters were located closer, and open mires around the breeding pool were more extensive. We propose that these habitat characteristics should be considered in nature conservation planning and management, as well as in environmental impact assessments. We found that with the current data, predicting pool occupancy and chick survival based on the selected habitat characteristics was not sufficiently accurate to replace field surveys and can only be used as a complementary method. We also emphasize the importance of freshwaters, potentially to be used for foraging in the surrounding landscape, which is an often-overlooked aspect in management and impact assessments.

Measuring nest size is an important aspect of studying the breeding biology of birds. Although some simple equations for estimating the volume of passerine nests are available, no methods to estimate nest size for gulls have been described. This paper offers an equation for calculating the volume of gull nests, based on the truncated cone. It requires only four measurements of the nest: outer diameter, inner diameter, height, and cup depth. We also present a way of estimating the volume of nest material.

The aim of this study was to estimate number of breeding pairs, breeding success, and distance to fishing areas in a population of the Red-throated Loon Gavia stellata on two of the main islands in the Holmöarna Archipelago in the northern part of the Baltic Sea, Sweden. Potential breeding waters were surveyed during seven years, 2010–2015 and 2019. Red-throated Loons appeared in 43 of the 135 lakes of sufficient size on the islands, and the population was estimated to 25–35 pairs, or about 2% of the Swedish population. The mean size of lakes with breeding pairs was 1.6 ha, and these lakes had an average of 82% water surface without vegetation (18% vegetation cover). The mean breeding success was low, 0.30 chicks per pair and year, and at least during one year, chicks were produced in only 20 (47%) of the surveyed lakes. The average distance between the nesting waters and the fishing areas for 17 studied pairs was 1.8 km. We discuss the characteristics of suitable nesting waters as well as the factors contributing to the low reproduction.


 Many studies have tried to estimate the number of birds killed by cats, most of them based on the number of birds killed by a smaller number of cats in a local area and then scaled to larger areas, or a whole country. Such estimates can be confounded by several factors, and the results of one study may not always be applicable in another setting where climate, habitats, and societal structure differ. Here I used an alternative approach to estimate cat predation on birds using ring recoveries of birds reported to the Swedish national ringing scheme as killed by cats. With the assumption that ringed birds are taken by cats in an equal proportion as unringed birds, I estimate that about 0.03% of all passerine birds are killed by cats in Sweden annually. This amounts to about 100,000 birds per year, which is much lower than previous estimates. 

After a long period of decline, the number of forest birds has increased in Sweden in recent decades. Whether this trend is due to an increase in forested area, forest quality, climate change, or a combination of these factors, remains unclear. Here, we compared forest bird data from a local winter point count route around Storuman in Swedish Lapland between 1986 and 2017, with the development of regional forest composition and local weather conditions. We suggest that rather than changes in average annual, winter, or summer local temperatures or precipitation, the main drivers behind increasing numbers of wintering forest birds in this part of Sweden are an increase in the area of denser forest and dead wood volume, and a decrease in open ground area without forest vegetation. While there may be supplementary explanations behind the increasing numbers of forest birds, such as reduced agriculture, decreasing local human population, or stronger photosynthesis, our results indicate that local land use has been favourable for forest birds in recent decades in this area.

The Mew Gull Larus canus is both a coastal and inland breeder and can be found on many different substrates, including man-made structures. It is known since long to nest in urban areas of Sweden, but neither the number of urban breeding pairs nor their behaviour have been well documented. We made some observations of breeding Mew Gulls in the city of Malmö in south Sweden and asked the chair of the tenant owners’ association that comprised one of the buildings with Mew Gull nest about the tenants’ experience of the species. Some perceive Mew Gulls as harmful because they dirty the roofs, leave a bad smell, are noisy, and defend their young with aggressive behaviours. Given the often-conflicting interests of gulls and humans, a better documentation of the nesting population in urban areas of Sweden, as well as their behaviour and interaction with people, is called for.

With its 25 confirmed breeding records between 2000 and 2015, the European Stonechat Saxicola rubicola is historically a rare bird in Sweden. The first breeding in the West Coast was found in 2014. Censuses performed in 2017 and 2018 revealed 28 and 30 breedings respectively. Out of 83 investigated territories, most were found in coastal heathlands in Halland. The arrival occurred in the turn of the months March/April and the majority of the males consisted of one year old birds (2CY). Fledgling date for 68 clutches were distributed from May to August. Second clutches were observed for ten out of 32 investigated breedings. The Swedish expansion should be seen in the context of Danish immigration in combination with a large-scale advance via the German Schleswig-Holstein area. The European Stonechat belongs to those range-expanding species that are expected to increase according to predictions of the future bird fauna. Due to warmer climate, plenty of appropriate habitats and high probability of reproduction, the conditions are good for a continued range expansion in southern Sweden.