Grey Breeding Research Articles

Grey seal Halichoerus grypus breeding sites contribute substantial carrion biomass to the Firth of Forth

Decomposing organic matter is central to the recycling of energy and nutrients in all ecosystems. Few studies have investigated the role of animal carrion biomass in ecosystem functioning, and quantitative data on carrion biomass are lacking. The role of carrion inputs in the marine environment specifically is poorly understood. The grey seal Halichoerus grypus breeding colony on the Isle of May in the Firth of Forth, Scotland, provides insight into the contribution of regular carrion pulses to the surrounding marine ecosystem. This study analysed 3 breeding locations with a range of topographies, elevations and tidal influences. Carcasses were mapped from aerial images and ground visual surveys in the 2008 and 2012 breeding seasons. Generalised linear mixed models were used to explore the degree to which breeding location and the position of a carcass influenced its availability to marine scavengers. Carcasses closer to shore were more likely to be completely displaced to the marine environment, and this effect varied with breeding location. An approximate 0.9 to 1.3 t of biomass per hectare of breeding site per year were released into the marine system. For carcasses that were below the high-water spring tide range but remained on shore, we quantified the typical duration of submersion to range from 5% to 44% of the time carcasses were ashore. Additionally, up to 808 kg of carrion was accessible to marine scavengers while washed by tides. Our results suggest breeding colonies of grey seals may contribute significantly to the carrion biomass available in local marine systems.

Theories and Technical Systems for Crop Grey Breeding Science and Their Applications

This study discussed the discipline structure of crop grey breeding science and its features and summarized the theories and technical systems for crop grey breeding science which are consisted of five systems, eight theories, nine principles, a technical route and a computer decision-making system. Under the guidance of the theories and methods, breeding workers have bred 27 new varieties, such as 4 wheat varieties, 3 mung bean varieties, 6 cotton varieties, 4 millet varieties, 1 soybean variety, 1 cowpea variety, 1 pumpkin variety, 1 sweet corn variety, 2 mulberry varieties, 1 silkworm variety, 3 reygrass varieties and so on. The popularization and application of these varieties in production has huge economic and social benefits, thus provides a strong support for the feasibility of theories and technical systems of crop grey breeding science from the perspective of breeding practice.

On the breeding of the Grey HeronArdea cinereain Algeria

During the period 2002–2012, we assessed the breeding status of the Grey Heron Ardea cinerea in Algeria by surveying all the major wetlands in the region. We located two distinct breeding sites; one of them was recorded for the first time. We also investigated nest site selection, measured breeding parameters and derived a growth curve for developing chicks. Although wintering Grey Herons increased in numbers in the region, the number of breeding pairs did not change markedly over the past century. The reasons for the scarcity of Grey Heron breeding pairs in Algeria and in the rest of North Africa are discussed.

The status of grey seals in Britain

Grey seal pup production in Scotland was estimated through annual aerial surveys of the main grey seal breeding colonies. Between 3 and 7 counts of pups were obtained for each colony at intervals through the course of the breeding season. Pup production for individual colonies was estimated from the series of counts using a maximum likelihood model. At 3 colonies, 2 in England, annual pup production was estimated using ground counts. Between the early 1960s and the early 1990s, grey seal pup production progressively increased. At colonies in the Inner and Outer Hebrides, production appeared to stabilize during the 1990s and has remained so. Pup production at colonies in Orkney and in the North Sea has continued to increase but in recent years the rate of increase has declined. This may imply that the UK grey seal population is reaching some limit to its size. The observed changes in pup production imply that some density dependent factors are affecting the British grey seal population. Changes in either juvenile survival and/or female fecundity are the most likely options. Without knowing which of these, or what combination of these factors, is operating, estimating total population size is complicated.

The response of Grey Herons Ardea cinerea to changes in prey abundance

Capsule Herons responded to the lower abundance of a preferred fish by switching prey. Aims To investigate how Grey Herons respond to the decline in abundance of a preferred fish, the Round Goby Neogobius melanostomus. Methods Grey Herons Ardea cinerea breeding in the Gulf of Gdańsk area (Baltic Sea) were the study population. Regurgitated food and pellets were analysed. Biomass and abundance of fish was compared between 2000–02 (when the population of Round Goby was increasing) and 2008–09 (when the Round Goby population stabilized). Results The abundance and biomass of Round Goby preyed upon by herons decreased from between 95 and 99% in 2000–02 to between 38 and 56% in 2008–09. Energy-rich salmonids, not recorded in 2000–02, were an important diet component in 2008–09 (42% of biomass). Small-sized fish abundance was higher in 2008–09 (37%) than in 2000–02 (9%). Conclusions Grey Herons in 2008–09 adapted to the lower availability of Round Gobies by prey switching to other available fish – abundant but small-sized Three-spined Sticklebacks Gasterosteus aculeatus and less abundant but more profitable salmonids (easy to catch in the case of hatchery-reared, tagged individuals). Diet composition suggests that Grey Herons in 2008–09 exploited more diverse foraging areas (dry habitats, woods, garden ponds) than in 2000–02.

Aerial surveying of grey seal breeding colonies on the Blasket Islands, Co. Kerry, the Inishkea Group, Co. Mayo and the Donegal Coast, Ireland

Summary The status of Ireland's grey seal population and its relationship with that of Britain and Western Europe, are poorly understood. The existing population estimate for grey seals in Ireland is outdated and urgency exists to establish a reliable national population estimate for this species, listed as an Annex II species under the EU Habitats Directive. Prior to the initiation of a survey on a national scale, the success or otherwise of aerial techniques in surveying grey seal breeding habitat on the Irish coastline first needs to be established. Previously, surveys were boat-based and were susceptible to adverse weather conditions frequently encountered during the autumn breeding season. The feasibility of using aerial techniques to survey grey seal breeding colonies in Ireland was tested during the breeding season of 2003.

Sibling Aggression and Breeding Success in the Grey Heron

Abstract Aggressive behavior of Grey Heron (Ardea cinerea) nestlings was observed in approximately 25% of the nests at two of three heronries (Kiersity and Kąty Rybackie; north Poland) studied in 2000-2002. Pecking (mostly at the youngest chick) was the commonest type of aggressive behavior (over 60% of cases). The chick mortality rate was higher in nests with sibling aggression than in other nests, however significant differences were found only at Kąty Rybackie. Foraging of parent birds nearby, in an area with abundant high quality and easily caught prey, could have caused the lack of sibling aggression in the colony at Mosty. At Kąty Rybackie, many chicks died in nests where aggressive behavior had been noted. It appears that siblicide, not predation, is the most important factor affecting Grey Heron breeding success in these colonies.

Grey Fantail breeding at Irymple, Vic.

Grey Fantail breeding at Irymple, Vic.