Climate change and the risks associated with delayed breeding in a tropical wild bird population

There is growing evidence of changes in the timing of important ecological events, such as flowering in plants and reproduction in animals, in response to climate change, with implications for population decline and biodiversity loss. Recent work has shown that the timing of breeding in wild birds is changing in response to climate change partly because individuals are remarkably flexible in their timing of breeding. Despite this work, our understanding of these processes in wild populations remains very limited and biased towards species from temperate regions. Here, we report the response to changing climate in a tropical wild bird population using a long-term dataset on a formerly critically endangered island endemic, the Mauritius kestrel. We show that the frequency of spring rainfall affects the timing of breeding, with birds breeding later in wetter springs. Delays in breeding have consequences in terms of reduced reproductive success as birds get exposed to risks associated with adverse climatic conditions later on in the breeding season, which reduce nesting success. These results, combined with the fact that frequency of spring rainfall has increased by about 60 per cent in our study area since 1962, imply that climate change is exposing birds to the stochastic risks of late reproduction by causing them to start breeding relatively late in the season.

Case study part 2: probabilistic modelling of long-term effects of pesticides on individual breeding success in birds and mammals

Abstract: Long-term exposure of skylarks to a fictitious insecticide and of wood mice to a fictitious fungicide were modelled probabilistically in a Monte Carlo simulation. Within the same simulation the consequences of exposure to pesticides on reproductive success were modelled using the toxicity-exposure-linking rules developed by R.S. Bennet et al. (2005) and the interspecies extrapolation factors suggested by R. Luttik et al.(2005). We built models to reflect a range of scenarios and as a result were able to show how exposure to pesticide might alter the number of individuals engaged in any given phase of the breeding cycle at any given time and predict the numbers of new adults at the season’s end.

Molecular barley breeding

Breeding progress in barley yield in the UK is being sustained at a rate in the order of 1% per annum against a background of declining seed sales. Commercial barley breeders are largely concentrating upon the elite local gene pool but with genotypic evidence suggesting that there is still considerable variation between current recommended cultivars, even those produced as half-sibs by the same breeder. Marker Assisted Selection (MAS) protocols could be substituted for conventional selection for a number of major-gene targets but, in the majority of cases, conventional selection is more resource efficient. Results from current QTL mapping studies have not yet identified sufficiently robust and validated targets for UK barley breeders to adopt MAS to assist in the selection of complex traits such as yield and malting quality. Results from multiple population mapping amongst the elite gene pool being utilised by breeders and from association studies of elite germplasm tested as part of the UK recommended list trial process do, however, show some promise.

British container breeding mosquitoes: the impact of urbanisation and climate change on community composition and phenology

The proliferation of artificial container habitats in urban areas has benefitted urban adaptable mosquito species globally. In areas where mosquitoes transmit viruses and parasites, it can promote vector population productivity and fuel mosquito-borne disease outbreaks. In Britain, storage of water in garden water butts is increasing, potentially expanding mosquito larval habitats and influencing population dynamics and mosquito-human contact. Here we show that the community composition, abundance and phenology of mosquitoes breeding in experimental water butt containers were influenced by urbanisation. Mosquitoes in urban containers were less species-rich but present in significantly higher densities (100.4±21.3) per container than those in rural containers (77.7±15.1). Urban containers were dominated by Culex pipiens (a potential vector of West Nile Virus [WNV]) and appear to be increasingly exploited by Anopheles plumbeus (a human-biting potential WNV and malaria vector). Culex phenology was influenced by urban land use type, with peaks in larval abundances occurring earlier in urban than rural containers. Among other factors, this was associated with an urban heat island effect which raised urban air and water temperatures by 0.9°C and 1.2°C respectively. Further increases in domestic water storage, particularly in urban areas, in combination with climate changes will likely alter mosquito population dynamics in the UK.

Agriculture modifies the seasonal decline of breeding success in a tropical wild bird population

1.Habitat conversion for agriculture is a major driver of biodiversity loss, but our understanding of the demographic processes involved remains poor. We typically investigate the impacts of agriculture in isolation even though populations are likely to experience multiple, concurrent changes in the environment (e.g. land and climate change). Drivers of environmental change may interact to affect demography but the mechanisms have yet to be explored fully in wild populations. 2.Here, we investigate the mechanisms linking agricultural land-use with breeding success using long-term data for the formerly Critically Endangered Mauritius kestrel Falco punctatus; a tropical forest specialist that also occupies agricultural habitats. We specifically focused on the relationship between breeding success, agriculture and the timing of breeding because the latter is sensitive to changes in climatic conditions (spring rainfall), and enables us to explore the interactive effects of different (land and climate) drivers of environmental change. 3.Breeding success, measured as egg survival to fledging, declines seasonally in this population, but we found that the rate of this decline became increasingly rapid as the area of agriculture around a nest site increased. If the relationship between breeding success and agriculture was used in isolation to estimate the demographic impact of agriculture it would significantly under-estimate breeding success in dry (early) springs, and over-estimate breeding success in wet (late) springs. 4.Analysis of prey delivered to nests suggests that the relationship between breeding success and agriculture might be due, in part, to spatial variation in the availability of native, arboreal geckos. 5.Synthesis and applications. Agriculture modifies the seasonal decline in breeding success in this population. As springs are becoming wetter in our study area and since the kestrels breed later in wetter springs, the impact of agriculture on breeding success will become worse over time. Our results suggest that forest restoration designed to reduce the detrimental impacts of agriculture on breeding may also help reduce the detrimental effects of breeding late due to wetter springs. Our results therefore highlight the importance of considering the interactive effects of environmental change when managing wild populations.

Breeding biology of the White-headed Vulture Trigonoceps occipitalis in Kruger National Park, South Africa

Information on the breeding biology of the White-headed Vulture Trigonoceps occipitalis is limited and published data are few. Within the Kruger National Park in north-east South Africa there is a regionally important population of about 60 White-headed Vulture pairs, of which 22 pairs were monitored for five years between 2008 and 2012 to determine key aspects of their breeding biology. Across 73 pair/years the mean productivity of 55 breeding attempts was 0.69 chicks per pair. Median egg-laying date across all of the Kruger National Park was 27 June, but northern nests were approximately 30 d later than southern nests. Mean (SD) nearest-neighbour distance was 9 976  7 965 m and inter-nest distances ranged from 1 400 m to more than 20 km, but this did not differ significantly between habitat types. Breeding productivity did not differ significantly between habitat types. The results presented here are the first for this species in Kruger National Park and provide details against which future comparisons can be made.

Attempted re-establishment of a sooty tern Onychoprion fuscatus breeding colony on Denis Island, Seychelles

Seychelles supports around three million nesting pairs of sooty terns. However, there have been recent declines and the colonies continue to face ongoing threats from habitat change and excessive commercial harvesting of their eggs, as well as potential threats by commercial fishing and climate change. A possible method to counter these threats is to re-establish breeding colonies on islands from which they have disappeared. An attempt was made to attract birds to a previously occupied island through habitat management, decoy birds and playback of recorded sooty tern calls. Habitat preparation involved predator eradication and tree removal to provide open ground with bare sandy areas and low herb vegetation. Overflying birds were attracted by broadcast calls, with some circling over and landing among the decoys. Large three-dimensional plastic models were superior to other models presented. This study demonstrated that large numbers of birds can be attracted by these means and that the birds then undertook behaviour associated with breeding, including egg laying by a few birds. However, after five seasons a breeding colony has not yet been established; one possible cause is the emergence of unexpected egg predators, common moorhen Gallinula chloropus and common myna Acridotheres tristis.

Genetic dissection of heterosis using epistatic association mapping in a partial NCII mating design

Heterosis refers to the phenomenon in which an F1 hybrid exhibits enhanced growth or agronomic performance. However, previous theoretical studies on heterosis have been based on bi-parental segregating populations instead of F1 hybrids. To understand the genetic basis of heterosis, here we used a subset of F1 hybrids, named a partial North Carolina II design, to perform association mapping for dependent variables: original trait value, general combining ability (GCA), specific combining ability (SCA) and mid-parental heterosis (MPH). Our models jointly fitted all the additive, dominance and epistatic effects. The analyses resulted in several important findings: 1) Main components are additive and additive-by-additive effects for GCA and dominance-related effects for SCA and MPH, and additive-by-dominant effect for MPH was partly identified as additive effect; 2) the ranking of factors affecting heterosis was dominance > dominance-by-dominance > over-dominance > complete dominance; and 3) increasing the proportion of F1 hybrids in the population could significantly increase the power to detect dominance-related effects, and slightly reduce the power to detect additive and additive-by-additive effects. Analyses of cotton and rapeseed datasets showed that more additive-by-additive QTL were detected from GCA than from trait phenotype, and fewer QTL were from MPH than from other dependent variables.

Observations on the Breeding Biology of the Collared Crescentchest (Melanopareia torquata)

The Collared Crescentchest (Melanopareia torquata) is an endemic bird of the Cerrado (Family: Melanopareiidae), and is listed in the State of Sao Paulo, Brazil as ""endangered"". We studied the breeding biology of Collared Crescentchest at two nests in the State of sao Paulo, southeast Brazil. Males were identified genetically and equipped with radio-transmitters. The incubation period was 12-16 days and the nestling period was 12-14 days. Nestling body mass was measured every second day for the first 10 days. Males participated in incubation and helped with nesting care. Measurements of eggs and nests are compared to those from the single previously known nest. These data are the first for any member of the Family Melanopareiidae. Received 27 March 2009. Accepted 28 August 2009.

BREEDING BIOLOGY OF KELP GULLS ON THE BRAZILIAN COAST

We studied clutch size, hatching and fledging success, and time necessary for chick Kelp Gulls (Larus dominicanus) to leave the nest throughout two breeding seasons (2004 and 2005) on Guararitama Island, Sao Paulo, Brazil. We followed 93 nests in 2004 and 97 nests in 2005. The average (+/- SD) clutch size was 2.09 +/- 0.64 in 2004 and 1.93 +/- 0.59 in 2005. Hatching success was 74% in 2004 and 53% in 2005, and fledging success was 54% in 2004 and 58% in 2005. Chicks grew quickly, following the linear equation y(t) = 61g + 17.03g X age (in days), and began to fly at 40 days. Received 11 August 2008. Accepted 28 August 2009.

Breeding of the Rufous-thighed Hawk (Accipiter erythronemius) in Argentina and Brazil

The Rufous-thighed, Hawk (Accipiter erythronemius) is a poorly-known, small raptor that dwells in forests and wooded savannas in south and eastern Brazil, Taraguay, eastern Bolivia, north and central Argentina, and Uruguay. We studied breeding biology and food habits of the Rufous-thighed Hawk from 1994 to 2007. We documented 14 breeding attempts recorded at nine nest sites in eight localities in Argentina and Brazil. Rufous-thighed Hawks were year-round residents at the study areas. The breeding season was c. 38 weeks long (June through March). Territorial behavior and courtship spanned for 22 weeks starting in mid June. Nest-building started in August. Nestlings were observed throughout December and into early January while fledglings were observed from late December through late March. Most nest sites were conifer plantations averaging 32.2 (SD = 10) years old, 12.6 ha (SD = 11.3) in size with trees averaging d 37.5 cm (SD = 13.5) of diameter at breast height. Nests were placed 20.2 m high (SD = 5.7), near the trunks of non-emergent conifers (Pinus sp. or Araucaria angustifolia). Nests were made of sticks, greater diameter averaging 48.8 cm (SD = 11.4), while nest depth averaged 23.3 cm (SD = 14). Prey items were birds (n = 49) ranging in size from c. 10 g [House Wren (Troglodytes, aedon)] to c. 140 g [White-tipped Dove (Leptotila verreauxi)]. Young started to chase birds at the age of 42-45 days in mid January. Adult males were primarily food providers but also aided in nest defense against other raptors. Females incubated, brooded, and fed young, and took leading roles in defense against humans. Rufous-thighed Hawks had unlined nests placed high in trees, and breeding season was markedly protracted.

The breeding biology of the White-faced Storm Petrel (Pelagodroma marina) on Mud Islands, Port Phillip Bay, Victoria

The White-faced Storm Petrel (Pelagodroma marina) is restricted to three breeding colonies within Victoria: Mud Islands and South Channel Fort in Port Phillip Bay, and Tullaberga Island off Mallacoota. Numbers of these storm petrels breeding on Mud Islands have declined considerably since early last century. White-faced Storm Petrels were recorded on Mud Islands from early September 2002 until mid-March 2003 when the last chicks fledged. Eggs were laid from late October to early December, with chicks hatching in the later half of December. The mean incubation period was 51.7 days (± 3.2 days (s.d.), range = 38–53, n = 13), and may have been extended by periods of egg neglect. The mean nestling period was 54.8 days (± 4.4 days (s.d.), range 50–70, n = 21). Chick growth is described. Hatching success was 54% and fledging success was 77.8%, with overall breeding success being 42%. Burrow densities were found to be influenced by plant species, vegetation height and soil moisture. The position of the burrow within the colony was shown to influence breeding success, with those nearer the edge of the storm petrel colony, closer to the marsh, and further from a colony of Australian White (Threskiornis molucca) and Straw-necked (T. spinicollis) Ibis recording higher success.