ASPECTS OF THE BREEDING STATUS AND ECOLOGY OF THE BATELEUR AND TAWNY EAGLE IN THE KALAHARI GEMSBOK NATIONAL PARK,SOUTH AFRICA

Herholdt, J.J., Kemp, A.C. & Du Plessis, D. 1996. Aspects of the breeding status and ecology of the Bateleur and Tawny Eagle in the Kalahari Gemsbok National Park. Ostrich 67:126-137.

The nesting success at 13 nesting territories of Bateleur Terathopius ecaudatus and 19 nesting territorites of Tawny Eagle Aquila rapax was monitored for seven successive years (1988–1994) in a protected area in the Kalahari desert of South Africa. On average Bateleurs laid one year in two (51/95 pair-years) and fledged 0.33 young/pair/year (31/95). Tawny Eagles laid, on average, in two out of three years (66/105), and fledged 0.4 young/pair/year (42/105). Most Bateleurs laid eggs in January and February, while Tawny Eagles mostly laid from May to June. Almost all Bateleur and Tawny Eagle nesting territories located were in the Acacia erioloba savanna in the dry Auob and Nossob riverbeds. Bateleur nesting territories were spaced at intervals of 7.2 km (2.5–14.6 km; n = 9) along the Nossob River. Tawny Eagle nesting territories were spaced at intervals of 17.6 km (6.1–32.7 km) in the Nossob River and 11.3 km (8–14 km) in the Auob River respectively. A total of 13 Bateleur and 30–40 Tawny Eagle nesting territories (27 known active nesting territories) respectively occurred in the Kalahari Gemsbok National Park during the study period. There was evidence of a 13% decline in active nesting territories of Bateleur during the seven year study, and at least a 40% decline over the previous 10 years. Vacated nesting territories were not reoccupied. There was no safe buffer zone around the Kalahari Gemsbok National Park and persecution in the adjacent farmlands, when foraging Bateleur from the protected Park enter these areas, as well as nesting site disturbance, could have been part of the reason for this decline. Poisoned and suspected poisoned Bateleurs have been found in the Park during the study period. There was no obvious decline in active Tawny Eagle nesting territories.     

POPULATION,DIET AND THE ANNUAL CYCLE OF THE LAUGHING DOVE AT BARBERSPAN,PART 4. BREEDING DATA AND POPULATION ESTLMATES

Dean, W. R. J. 1980. Population, diet and the annual cycle of the Laughing Dove at Barber-span, Part 4: Breeding data and population estimates. Ostrich 51:80-91.

From 1974–1976, Laughing Doves Streptopelia senegalensis raised an observed total of 436 young in 619 nest attempts, giving a breeding success of 0,70 young per pair nest attempt, or an overall success of 0,35 young per egg. Breeding success, estimated by computing the probability of survival of an egg through the incubation period, and of a chick through the nestling period suggest that the breeding success is about 0,33 young per egg. Nests were found in every month of the year, though there was a tendency for breeding to be concentrated during the late rainy season and the dry season. The mean annual population size of the Laughing Dove in the study area was estimated at 221 adults and juveniles by one method and at 237 adults and juveniles by another method. The number of young produced each year is correlated with the estimated population size for each year.     

4. UNUSUAL EXPERIENCES WITH BIRDS

Earlé, R. A. 1989. Breeding biology of the Redbreasted Swallow Hirundo semirufa. Ostrich 60: 13–21.

The two races of the Redbreasted Swallow Hirundo semirufa seem to have separate breeding seasons with the northern race H. s. gordoni breeding April-July, while most records for the nominate race fall in October-February. All nests studied were in concrete culverts less than 1 m high. Eggs laid in second clutches by individual females weighed significantly less than eggs laid in first clutches. Eggs hatched on average 16,2 days after incubation started or 18–21 days after the eggs were laid. Only females incubated. Chicks fledged 23–25 days after hatching and reached a maximum body mass of about 31,5 g on day 18 before a steady decline in mass until fledging. Most nesting failures resulted from infertile eggs or starvation of young in the nest (16,2% of all young starved). Overall breeding success was 60,6%. In all, 81,8% of first clutches produced fledglings but only 44,4% of second clutches. Over a three year period 4,9 young were produced per pair breeding in the area (1,6 young/pair/breeding season).     

Extra-pair young despite strong pair bonds in the European Nuthatch (Sitta europaea)

We choose the European Nuthatch (Sitta europaea), an extremely socially monogamous passerine species, to investigate the breeding biology and frequency of extra-pair activities of females. Breeding individuals live in strong pair bonds for their total life and defend their territory all year round. As a consequence of these narrow social bonds, nuthatches have to date been considered extremely sexually monogamous. Our genetic study, however, reveals a minimum of 10% of extra-pair young in 188 chicks from 32 broods in populations of southwestern Germany. Independently of the habitat type (high via low quality), most of extra-pair sires are identified as neighbouring territory holders.     

The effect of body condition on the timing and success of breeding in Little Penguins Eudyptula minor

We studied the effect of parental body condition on the breeding biology of Little Penguins Eudyptula minor . Daily attendance patterns and body mass were recorded using an Automated Penguin Monitoring System, which collected arrival and departure masses for approximately 200 breeding birds over the 2000 and 2001 breeding seasons. Breeding success varied between the two years; 2000 was a year of average breeding success (fledging 1.07 chicks per pair), and 2001 a year of poor breeding success (fledging 0.53 chicks per pair). In both years, adult body condition (body mass divided by flipper length) increased significantly prior to laying. The laying period began over a month later in 2000 than in 2001, and birds in 2000 exhibited significantly better body condition at laying. However, the mean laying dates in 2000 were less variable than in the 2001 breeding season. Body condition appeared to influence both the time of breeding and breeding synchrony in Little Penguins. Breeding success was correlated with adult body condition at incubation in 2000 but not in 2001, indicating that success was not solely influenced by adult body condition at incubation.     

A 13-YEAR POPULATION STUDY OF THE BLACK EAGLES IN THEMATOPOS,RHODESIA, 1964–1976

Gargett, V. 1977. A 13-year population study of the Black Eagles in the Matopos, Rhodesia, 1964–1976. Ostrich 48:17-27.

The resident black Eagle Aquila verreauxi population in approximately 620 km² of the Matopos, Rhodesia, underwent changes from 1971 and appeared less stable than in the first five years. Six new territories were established in the National Park; two territories in Tribal Trust Land were abandoned; one territory in the National Park vacant for five years and one in Tribal Land vacant for at least 11 years were reoccupied. breeding data covering 13 years confirm the five-year findings. In 652 pair-years 442 breeding attempts were made with 339 young eagles f edging: a reproductive success rate of 0,52 young per pair per year. On average 68 % of the population bred every year, each pair attempted breeding in two years out of three, and one attempt in four was unsuccessful. Annual and individual variations in breeding performance were considerable, from 46% to 89% of the population breeding, and from two successes in six attempts for one pair to 12 successes in 12 attempts for two pairs. Over 13 years the percentage of the population breeding annually followed the form of a sine curve with a ten year period.

Fourteen factors that might affect annual and/or individual performance are considered. Below average rainfall years were followed by above average breeding; and generally fewer clutches were laid early after heavy rainfall in the three months preceding laying. Clutches laid late were less successful than those laid early. Breeding was affected by the proximity and intervisibility of nests, the previous year's performance and intraspecific disturbance. Appropriation of nests by other species prevented breeding and no new pair bred while establishing or re-establishing its territory. Building a new nest was followed by laying in the same season only if the nest was completed by mid-May, the peak laying period, building or partly building two nests in one season did not prevent breeding in the following year. At least 76% of clutches were c/2. The causes of two eaglets' deaths were ascertained and the remains of two adults were found. Pairs with territories in Tribal Trust Land had a significantly lower breeding performance than pairs in the protected National Park. Only traces of pesticide residues were found in four eggs. Observers' visits did not affect reproductive success.     

The breeding biology of the Common Crossbill Loxia curvirostra in the Central Pyrenees

The breeding biology of the Common Crossbill Loxia curvirostra was studied over ten consecutive years in forests of Mountain Pine Pinus uncinata in the Pyrenees, France. The breeding season lasts from summer to the next spring following the maturation and the opening of the pine cones. Pairs with dependent young were most common in November and March–May. The greatest number of clutches was observed in December and January (53%, n = 30). Average clutch size was 3.43 eggs (sd = ±0.57; n = 30), the number of fledged young was 1.32 per completed clutch (sd = ±1.7; n = 25) and the proportion of breeding attempts that were successful was 27.8% in the winter/spring period (n = 36). The number of successful pairs was found to be positively correlated to the number of cones, and in the winter/spring period negatively correlated to the mean depth of snow. Breeding only failed completely during the year in which the density of birds was highest. In years with a good cone crop, breeding that starts early and continues over a long period appears to be an adaptation which increases productivity in this sedentary population dependent on fluctuating food resources. An irruption by birds from northern Europe in 1990 did not affect the numbers or breeding success of the Pyrenean crossbills.     

BREEDING DENSITY AND NEST SITE CHARACTERISTICS OF THE PEREGRINE FALCON FALCO PEREGRINUS MINOR IN THE SOUTHWESTERN CAPE,SOUTH AFRICA

Pepler, D., Van Hensbergen, H.J. & Martin, R. 1991. Breeding density and nest site characteristics of the Peregrine Falcon Falco peregrinus minor in the southwestern Cape, South Africa. Ostrich: 62: 23–28.

A survey of nest sites and nest site characteristics is used to obtain an estimate of the breeding density of the Peregrine Falcon Falco peregrinus minor in the southwestern Cape, South Africa. The breeding density from a small intensively studied area around the town of Stellenbosch is extrapolated to the region. This extrapolation is justified since nest site characteristics suggest that suitable sites are widespread in the region. Lower and upper estimates of 48 and 95 pairs respectively were obtained for the area above 300 m. This gives densities of one pair per 199 km² for the lower estimate and one pair per 100 km² for the upper estimate. For the entire study area the densities are one pair per 806 km² and 407 km² respectively.     

Breeding biology of the Red Kite Milvus milvus in Corsica

The breeding biology of the Red Kite Milvus milvus is still little known in the southern part of its range (Mediterranean), despite recent conservation concerns and major declines in most insular populations (Sicily, Sardinia and Balearics). We report here on the breeding biology of the Red Kite in Corsica in 1996–99 and on recent population trends there. In a 42‐km² study area located in the northwest of the island (Balagne region), breeding density was locally high (1.17–1.78 breeding pairs/km²). Breeding dispersion ranged from loosely colonial to dispersed, with average nearest‐neighbour distance of 444 ± 316 m (range 50–2000) (all data as means ± sd). Kites established breeding territories in January–February, and 92.4% of territorial pairs laid a clutch (n = 238). Laying took place between February and May (mean lay date: 27 March ± 16 days, n = 147). Clutch size averaged 2.44 ± 0.71 (1–5 eggs, n = 96), hatching success 66.9% and fledging success 78.6%. Productivity averaged 1.33 ± 0.88 young per breeding attempt (n = 221) and 1.65 ± 0.65 young per successful breeding attempt (n = 173). Overall breeding success was 51.4 ± 38.0% (n = 88). We describe the growth of young (wing, weight, tarsus and bill) and show a marked seasonal decline in clutch size and breeding performance, with pairs laying earlier producing larger clutches and being more successful than later breeding pairs. Unlike most other insular Mediterranean Red Kite populations that have recently declined, the breeding population in the northwest of Corsica, which accounts for c. 25% of the whole island population, increased from 25 to 35 pairs in 1989 to a maximum of 80–90 pairs in 1997. This increase was probably related to the lack of persecution and a local increase in abundance of Rabbits Oryctolagus cuniculus, following their introduction in the late 1970s, which provided an important feeding resource for Kites. Finally, we compare our results with those from other Red Kite populations studied in Europe. We found that there is a latitudinal gradient in laying date and productivity across Western Europe populations, but no evidence of an insular syndrome in the Corsican population.     

Nesting Biology of Urban Cooper's Hawks in Milwaukee,Wisconsin

ABSTRACT Urban landscapes vary greatly across North America and long-term data on the nesting biology of Cooper's hawks (Accipiter cooperii) from a variety of urban environments will improve our understanding of these poorly studied populations. We studied Cooper's hawks nesting in the metropolitan Milwaukee area, Wisconsin, USA, over a 12-year period, 1993–2004. Nesting success for 254 first nesting attempts averaged 64.6% with means of 2.27 young per laying pair and 3.53 young per successful pair. For 8 second nesting attempts (i.e., re-nests), nesting success averaged 87.5% with means of 2.57 young per laying pair and 3.00 young per successful pair. Productivity for first nesting attempts did not vary over the 12-year period, and productivity for re-nests did not differ from first nesting attempts. We documented evidence of nest predation by raccoons (Procyon lotor) and red-tailed hawks (Buteo jamaicensis). On average, second year (SY [i.e., 1-yr-old]) Cooper's hawks comprised 14.6% (43 of 295 breeding birds; 21.5% [37 of 172] of F and 4.9% [6 of 123] of M) of the known breeding population. The percentage of SY breeders within this population declined over the 12-year period, suggesting a relatively young population. Cooper's hawks consistently reoccupied nest sites annually after initial discovery over an estimated 2 generations of breeding adults, suggesting that population density for our study was at least stable. We trapped 105 breeding adults, including 5 natal dispersal birds. Based on long-term, relatively high reproduction, repeated re-occupancy of nest sites, and confirmed recruitment from within this population, we suggest that these nesting areas were not marginal or inferior habitats and that urban Cooper's hawks in this study area were not a sink population. We recommend no active management of this population at this time; however, additional information for nesting Cooper's hawks from other urban environs will expand our knowledge base for these populations.     

BREEDING BIOLOGY OF THE BEARDED VULTURE IN SOUTHERN AFRICA,PART II: THE NESTLING PERIOD

Brown, C. J. 1990. Breeding biology of the Bearded Vulture in southern Africa, Part I: The nestling period. Ostrich 61: 24–32.

The nestling period of the Bearded Vulture Gypaetus barbatus in southern Africa was 124–128 days. The hatching interval between the normal two-egg. clutch was usually 3–6 days (range 2–9 days Only one nestling per clutch survived to the third day. Tittle sibling aggression and no infanticide took place, but the older nestling dominated the younger which obtained no food. For the first 40 days the nestling was closely brooded. The nest duties were evenly shared by both parents, but females brooded at night. Food was brought to the nest usually once or twice per day by both parents, and was stored behind the nest. During days 41–90 parental attendance steadily decreased. Dunng this stage the female spent more time in the nesting area (57%) and on the nest (91%) than the male. Towards the end of this stage the nestlin started to feed itself but preferred to be fed by a parent. From da 91 to first flight the nestling was left unattended and was visited by its parents only to provide food, which it fed from itself. All pars monitored (40 pair-years) attempted to breed every year. The breeding success (n = 18 pair-years) was 0,89 young fledged per pair per year.     

Habitat selection by dispersing yellow-headed blackbirds: evidence of prospecting and the use of public information

In migratory birds individuals may prospect for potential breeding sites months before they attempt to breed and should use the cues most predictive of future reproductive success when selecting a breeding site. However, what cues individuals use when prospecting and which cues are used in selecting a breeding site are unknown for most species. I investigated whether yellow-headed blackbirds (Xanthocephalus xanthocephalus) prospect for future breeding sites and whether they select breeding habitats based on food availability, male or female density, or the average number of young produced per female in the previous year. Although it is often assumed that migratory birds prospect for potential breeding sites at the end of the breeding season, I investigated this by recording all visits to sites early and late in the breeding season. I found that males and females who visited sites other than the site at which they bred were more likely to disperse than individuals only observed at the site where they bred, and that males and females were more likely to prospect late in the breeding season. Both food availability and density in year ^x were not predictive of the number of young per female in year ^x+1; however, the number of young produced per female at a site in year ^x was predictive of the number of young per female in year ^x+1. As expected, dispersers used the most informative cue, the number of young per female and moved to sites with a relatively high number of young per female. This study suggests that individuals prospect for potential breeding sites late in the breeding season when they can use information gathered from the reproductive success of other individuals (i.e., public information) to select a breeding site.     

Breeding ecology of a suburban population of Woodpigeons Columba palumbus in northwest England

Capsule Between 1981 and 2008 population size was stable, but there were negative trends in breeding parameters.

Aims To determine the current status and long‐term population trend of an isolated breeding population of Bearded Vultures Gypaetus barbatus (Corsica, Mediterranean).

Methods The total Bearded Vulture population was monitored between 1981 and 2008.

Results The current effective breeding population size of Bearded Vultures in Corsica is ten pairs/trios with a slight increase of one to two pairs since 1983. The population is currently estimated at 25 individuals. Breeding parameters (laying rate, breeding success and productivity) have decreased significantly over the full 28‐year study period, although the decrease was not significant when the data set was restricted to 1988–2008. A mean of 60.3% (n = 204) of pairs have laid, but this proportion is highly variable between years. Productivity has been very low (0.16 young/pair/year, n = 233). Breeding parameters of the Corsican population of Bearded Vultures are very low compared with those of other western European populations in the Pyrenees.

Conclusions This isolated insular population is of small size (eight to ten pairs/trios) but shows a stability of distribution and numbers, but low (and decreasing) breeding rates, making this insular population one the most threatened in Europe.     

BREEDING BEHAVIOUR OF OSPREYS PANDION HALIAETUS IN SCOTLAND

Ospreys Pandion haliaetus nested at a site near Loch Garten, Inverness-shire continuously from 1959 to 1973. Each year the Royal Society for the Protection of Birds has organized a continuous watch on the eyrie in the breeding season. The detailed records kept of the activities of Ospreys at the nest by those participating in the watch were analysed and the results presented here. Ospreys are migratory and arrived in the breeding area in early April. Nesting material was usually added to an existing eyrie platform. The male collected more material than the female. The female lined the nest cup. The extent of nest building activity and the frequencies of mating and other activities prior to laying varied markedly from year to year. These differences may have been related to changes in the identity of the nesting female, but the birds were not individually marked. Both sexes incubated but the female took the greater share and normally incubated at night. When the young hatched they were brooded by the female. The female stayed in the vicinity of the nest for most of the time until the young fledged at about 53 days old. The male Osprey caught almost all the fish eaten by his mate and young during the breeding season. The number of fish caught per day increased markedly after the young hatched. Pike Esox lucius and Trout Salmo trutta were the main species taken, and some Rainbow Trout Salmo gairdnerii were identified. There were seasonal and diurnal changes in the size and the species composition of the catch. The effects of weather conditions on hunting are examined. The occurrence of Ospreys other than the resident birds at the nest site is described. The behaviour of another pair of Ospreys which repeatedly failed to hatch eggs is described. There was an instance of egg eating in this pair, and some differences in behaviour were found between these birds and those at Loch Garten whose breeding success was good. The breeding biology of Ospreys is compared with that of other British diurnal birds of prey. In other species the female leaves the young unguarded at some stage in the nestling period and hunts food for them, whereas female Ospreys do not usually hunt in the nesting period.     

1. ADDITIONAL NOTES ON THE BIRDS OF BLOEMHOF DISTRICT

Olver, M.D. 1984. Breeding biology of the Reed Cormorant. Ostrich 55:133-140.

The breeding biology of the Reed Cormorant Phalacrocorax africanus was studied at Cedara Dam, Natal, South Africa, from 1973 to 1975. Breeding occurred from November to February and was preceded by a period of courtship. Mean clutch size was 3,6 eggs and mean egg measurements were 44,2 x 29,5 mm. The average incubation period was 23,3 days. Young leave the nest at 28 days when alarmed but cannot fly until 35 days old. Hatching success was 84,1%, and fledging success 60,6%.     

6. GENERAL NOTES

Stutterheim, C. J. 1982. Breeding biology of the Redbilled Oxpecker in the Kruger National Park. Ostrich 53:99-90.

The nest of the Redbilled Oxpecker Buphagus erythrorhynchus in the Kruger National Park is a natural hole in a tree where no excavation is required. No evidence of a territorial system WBS observed and only the nesting tree is defended. Mammal hair, dung, grass and rootlets are used for nesting material. The average clutch size was 2.8 eggs with a mean incubation period of 12,6 days. The average nestling period was 30 days. The Redbilled Oxpecker can raise three broods in a season of 176 days such as in the 1973/74 breeding season. The activity area of one breeding group was 7,0 km². The breeding unit consists of two to five birds with helpers of both sexes. All the birds in a group help to select a nest site, build the nest and feed the young. Only one male and one female participate in incubation. Post-hatching development was studied in 13 chicks.     

Effects of acidification on the breeding ecology of a stream‐dependent songbird,the Louisiana waterthrush (Seiurus motacilla)

1. We compared breeding ecology of the Louisiana waterthrush (Seiurus motacilla) on acidified and circumneutral streams in the Appalachian Highlands of Southwestern Pennsylvania from 1996 to 2005. 2. Headwater streams impacted by acid mine drainage and/or acidic precipitation showed reduced pH (range 4.5–5.5) compared to four circumneutral streams (pH c. 7). Acid‐sensitive taxa, including most mayflies (Ephemeroptera), were almost completely absent from acidified streams, whereas several acid‐tolerant taxa, especially stonefly (Plecoptera) genera Leuctra and Amphinemura, were abundant. 3. Louisiana waterthrush breeding density (c. 1 territory km^?1) was significantly reduced on acidified streams compared to circumneutral streams (>2 territories km^?1). Territories on acidified streams were almost twice as long as on circumneutral streams. Territories usually were contiguous on circumneutral streams, but they were often disjunct on acidified streams. Breeding density declined on one acidified stream that we studied over a 10‐year period. 4. Clutch initiation was significantly delayed on acidified streams, on average by 9 days in comparison to circumneutral streams, and first‐egg dates were inversely related to breeding density. Birds nesting along acidified streams laid smaller clutches, and nestlings had shorter age‐adjusted wing lengths. Stream acidity had no effect on nest success or annual fecundity (fledglings/female). However, the number of young fledged km^?1 was nearly twice as high on circumneutral streams as on acidified streams. 5. Acidified streams were characterized by a younger, less site‐faithful breeding population. Individuals were less likely to return multiple years to breed, allowing inexperienced breeders to settle on acidified streams. Pairing success was lower on acidified streams, and we observed four cases of waterthrushes emigrating from territories on acidified streams to nearby circumneutral streams in the following year. 6. We conclude that acidified headwaters constitute lower quality habitat for breeding Louisiana waterthrush. However, breeding birds can apparently compensate for reduced prey resources to fledge young on acidified streams by increasing territory size, foraging in peripheral non‐acidified areas, and by provisioning young with novel prey.     

Influence of climate on Bonelli's eagle's (Hieraaetus fasciatus V. 1822) breeding success through the Western Mediterranean

Aim To assess the impact of certain climatic variables on the breeding success of some populations of Bonelli's eagle (Hieraaetus fasciatus V. 1822) throughout its latitudinal distribution range, in order to account for recent and differential declines in populations. Location Western Mediterranean, from southern Morocco to southern France. Methods Seven populations were considered for the latitudinal distribution range of the species. Data from 1052 breeding attempts were taken from the literature and, for each population, breeding success was measured as the mean number of fledglings per pair per year. Breeding success, as a dependent variable, was related to five geographical and climatic variables (latitude, mean annual temperature, mean minimum temperature of the coldest month, mean maximum temperature of the hottest month and mean annual precipitation) as independent variables, through some regression models, which take into account the multicolinearity of the variables. Results All the analyses agreed that average annual temperature was an important factor associated with the breeding success of the species in each region, and accounted for up to 97% of the variance of the breeding success throughout a latitudinal gradient in the study area. Main conclusions The low breeding success of the northern populations (probably because of climatic constraints) and the tendency of juveniles to disperse southwards, diminishes recruitment in those populations. Therefore, as human pressure and habitat destruction causes high adult and pre‐adult mortality of the species throughout its entire latitudinal range, disturbances in the northern populations have more profound effects, thereby explaining observed population declines.     

Densities and dispersion of breeding Eurasian Hobbies Falco subbuteo in southeast England

Capsule Breeding Hobbies are more numerous in parts of southeast England than previously recognized, and in suitable habitat their breeding dispersion shows a regular pattern.

Aims To establish the density and breeding dispersion pattern of a population of Hobbies in southeast England.

Methods Surveys to locate every pair of Hobbies present were conducted in six study areas of between 48.0 and 201.2 km² in three counties in southeast England during 2005–10.

Results Each study area held between 7 and 21 pairs. Densities were higher than in previous studies conducted in Britain, at between 9.0 and 15.0 pairs per 100 km². Mean densities per unit area of non-developed habitat were also consistently higher than expected, at between 10.1 and 17.3 pairs per 100 km². The mean nearest known neighbour distances fell within the range 1.8–2.8 km. In all six study areas, pairs were regularly spaced. The majority (68.0%) of nesting and territorial pairs occupied sites in woodland.

Conclusions Breeding Hobbies are considerably more numerous in parts of southeast England than previously recognized, and numbers appear to be continuing to increase. Accurate population estimates for Hobbies require species-specific fieldwork.