Intraspecific variation in size and density of Avocet colonies: effects of nest-distances on hatching and breeding success

In many colonial bird species there is considerable intraspecific variation in colony size and inter‐nest distance (colony density). Possible causes of this variation and its effects on hatching success (survival of eggs) and breeding success (probability of a pair raising chicks) were studied in 48 Avocet Recurvirostra avosetta colonies in Schleswig‐Holstein (Germany) between 1991 and 1996. Colony density was influenced by time of year and habitat (categories: island or mainland, close to or far from feeding grounds). Colonies on islands had the highest densities. When all available space at a colony site was used, colonies became very dense (mean nearest‐neighbour nest distance less than 1 m). Colony size (number of clutches) was influenced by time of year, but not by habitat. Hatching success was low in high density colonies and in very low density ‘colonies’ (single nests) and high over a broad range of intermediate nest densities. The low success rate of single nests was caused by a very high predation rate, whereas the low success rate in very dense colonies was caused by a high rate of nest abandonment. Nest abandonment in very dense colonies was associated with a high level of aggressiveness among Avocets during the egg‐laying period. Due to territorial behaviour, Avocets seemed to be expelled from the densest breeding sites. In very dense colonies, high frequencies of clutches of unusual size occurred due to conspecific nest parasitism. The number of Avocets taking part in attacks on potential egg predators was small and (in colonies of more than one clutch) depended neither on colony size nor on colony density. Despite a low hatching success in very dense colonies, individuals breeding in the densest colonies had significantly better chances of raising chicks than Avocets breeding in less dense colonies. Coloniality seemed to be obligatory for Avocets in order to ensure hatching success. The size and density of colonies seemed to be associated with the availability of suitable nesting habitats (islands).     

Habitat selection and breeding success in Yellow-legged Gulls Larus cachinnans

The habitat selection and breeding performance of Yellow-legged Gulls Larus cachinnans were studied in the Medes Islands colony, northeastern Spain, during 1995 and 1996. Of the three main habitats on the islands (shrubs, grass and bare areas), gulls first occupied those with the highest percentage of tall vegetation. Gulls tended to select nest sites with 20–75% cover despite great differences in the cover in the habitats and territories, suggesting that the presence of a suitable nest site may play a major role in the choice of breeding habitat. Nest-site tenacity did not influence the preferences of gulls at any level since the same pattern of choice was observed in an area subjected to annual culls (i.e. where most of the breeding pairs were culled annually and replaced by naive birds). In spite of great differences in the physical characteristics of the habitats, little difference was found in breeding performance of the gulls between habitats. Gulls nesting in the least preferred habitat (i.e. mainly bare) had smaller clutches than those nesting in the other two habitats, possibly as a result of their later seasonal laying. Despite the similar breeding success in different habitats, gulls did not seem to distribute according to the ideal free model reported for Herring Gulls Larus argentatus since the density in the preferred habitat (i.e. shrubs) was never higher than in the other two. We suggest that the habitat selection by Yellow-legged Gulls within the colony could follow an ideal despotic distribution.     

Low reproductive success of the endangered Takahe Porphyrio mantelli on offshore island refuges in New Zealand

Many of New Zealand's endangered birds have been transferred from the “mainland” of the North and South Islands to smaller coastal islands free from introduced predators and competitors. The transfer of Takahe Porphyrio mantelli (Plate 1) to offshore islands is unique because these highly endangered, flightless rails are being moved from alpine-tussock habitat of Fiordland, the last remaining natural population, to substantially different lowland habitat on island refuges. Despite the fact that 30% of the approximately 160 Takahe left in the wild now live on coastal islands, a detailed analysis on the success of the island populations has never been undertaken. Using data available from New Zealand's Department of Conservation, we found that while adult survivorship of Takahe on islands is high, reproductive success is significantly lower than in Fiordland. Most factors examined, including inbreeding and nutrient deficiency, had no significant effect on reproductive success of Takahe breeding on islands. Island pairs produced fewer eggs and juveniles in the first year of their pair bond relative to all other years. Hence the large number of transfers of birds between islands during the initial stages of the relocation program may have resulted in a higher frequency of pair formation and thus may have contributed to the islands' lower reproductive success. Why first clutches did so poorly (four juveniles from 43 clutches) compared with second (11 from 36) and third (six from 13) clutches is not known but was one of the main contributing factors for island pairs making greater nesting effort but significantly lower returns than birds breeding in Fiordland. In addition, some individual birds have been very successful in producing young relative to other birds, suggesting that important differences in quality of some breeders may also exist. We expect island productivity will improve over time as the number of interisland transfers of Takahe decreases and as the proportion of breeding birds raised in the island environment increases.     

Influence of weather on reproductive success of northern fulmars in the Canadian high Arctic

The northern fulmar (Fulmarus glacialis) is a common seabird of the North Atlantic Ocean, with breeding colonies broadly dispersed between 45°N and 80°N. At higher latitudes, breeding fulmars experience extensive sea-ice and presumably snow and low temperatures which do not affect fulmars in the southern part of the breeding range. We studied the relationship between weather and reproductive success of northern fulmars breeding at two colonies in the Canadian high Arctic. Collectively, hatching success, fledging success, and productivity (chicks fledged per egg laid) were similar between our study and results from colonies located south of the Arctic. However, a larger proportion of fulmars at apparently occupied sites (AOS) in high Arctic colonies appeared to forego egg-laying, resulting in lower proportions of chicks fledged per AOS. Extreme inclement weather was the major factor influencing nesting success, resulting in pulses of egg or chick loss during or immediately following major storms, although the mechanism of effects appeared to differ between the two colonies. For Arctic fulmars, the risks of nest failure due to stochastic, deleterious weather events may be offset by the predictable abundance of food supplies during chick-rearing in Arctic waters.     

Constrained by available raptor hosts and islands: density-dependent reproductive success in red-breasted geese

In this paper we aim to explain the distribution of red-breasted geese Branta ruficollis over different nesting habitats. To be safe from land predators red-breasted goose colonies were restricted to i) islands on rivers, ii) cliffs with peregrine falcons Falco peregrinus , and iii) the close proximity of snowy owl Nyctea scandiaca and rough-legged buzzard Buteo lagopus nests. Among years nest site availability varied by fluctuations in numbers of owls and buzzards in association with cycles in lemming abundance, but the total number of goose nests found in the study area did not vary. The distribution of geese, in combination with data on reproductive success, suggested a despotic mechanism: at cliffs, goose numbers were constant among years with an invariably high reproductive success, whereas large fluctuations in numbers on islands coincided with opposite trends in success. Apparently, geese nesting with owls or buzzards moved to the few islands present in the study area during years when these birds of prey were absent. Consequently, in such years the average density of geese on islands was more than twice as high as at cliff colonies (5.4 and 2.3 pairs per ha of foraging habitat, respectively). Colony size at cliffs may have been restricted by territorial behaviour of the geese, though there is evidence that, additionally, the host falcons also limited the number of nesting geese. Apparently rare in closely related species, we observed a negative density-dependent effect on reproductive success during the nest phase, and attribute this to limited food resources, reinforced by the high frequency of territorial interactions. This leads to the conclusion that, in addition to predation pressure, nesting density is an important agent in the link between lemming cycles and goose breeding success.     

Are salinas a suitable alternative breeding habitat for Little Terns Sterna albifrons?

This paper describes the breeding population, breeding habitats and reproductive variables of Little Terns Sterna albifrons in natural (sandy beaches) and alternative (salinas) habitats. Studies of nesting success conducted between 1998 and 2002 in these two types of habitat were combined with a literature review of census work from the past 30 years in order to assess whether salinas are suitable alternative breeding habitat for Little Terns. Most of the Portuguese Little Tern population now breeds in salinas. Census data from the last 30 years show that this is a recent breeding behaviour, because until the 1990s most colonies were located on sandy beaches. Destruction and disturbance of the natural habitat has caused this habitat shift. Despite this shift, the Portuguese Little Tern breeding population did not decline during this period and no significant differences were found in nesting success between natural and alternative habitats. This might indicate that salinas are a suitable alternative breeding habitat for Little Terns, but differences in laying period, clutch size and egg size were recorded between birds nesting on sandy beaches and in salinas in the same area. Birds nested earlier on sandy beaches and laid larger clutches and eggs than in salinas. These data suggest that, when both habitats are available, older and/or higher quality birds prefer sandy beaches for breeding, presumably trying to re-nest in salinas when first breeding attempts failed. We discuss conservation priorities and management actions for both habitats.     

Little tern breeding success in artificial and natural habitats: modelling population growth under uncertain vital rates

As a consequence of habitat loss, breeding in man-made habitats has become increasingly common for many coastal breeding bird species. While artificial sites provide valuable substitutes, they may also be more attractive, and importantly, differ in quality from natural sites. Therefore, information on habitat specific breeding success and their potential for supporting stable populations are needed. We compared little tern (Sternula albifrons) breeding success (nest and hatching success) between natural habitat (sandy beaches) and artificial port habitat at Bothnian Bay, Finland from 2006 to 2011. We further reviewed published estimates on pre-fledging and adult survival for little terns and least terns (Sternula antillarum), and used these ranges to estimate plausible parameter spaces for population growth rates given our estimates of breeding success. Nest success was among the highest reported for little terns in the artificial habitat (82 %) while being lower in the natural habitat (58 %). This difference may have resulted from differences in colony sizes and levels of disturbance. Hatching success did not differ significantly, but the percentage of successful nests containing unhatched eggs was twice as high in the natural habitat. The parameter spaces for population growth rates indicated that the artificial habitat has good potential to sustain stable populations (66 % positive growth rate) while for the natural habitat this potential was lower (37 % positive growth rate). While our results suggest that artificial habitats can be very productive breeding sites for habitat deprived tern populations, management should concentrate on improving both habitats with emphasis on natural sites.     

Population dynamics and reproduction of Northern Lapwings Vanellus vanellus in a meadow restoration area in central Sweden

To investigate the effectiveness of a meadow restoration programme, we studied the relationships between population changes and environmental changes, return rates and hatching success in a population of Northern Lapwings Vanellus vanellus. The study was performed on mixed farmland (59 km²) in central Sweden, an area that underwent extensive meadow restoration between 1985 and 1994. The study included more than 2600 nests, supplemented with observations of 127 individually colour-ringed Northern Lapwings. The breeding population varied (2.7–5.3 pairs/km²), but showed no significant trend with time. The population increased in years with high spring flooding levels. Population size was unrelated to demographic factors (e.g. hatching success the previous year (14–50%), and return rate). Lapwings moved considerably between years and their nest site fidelity was unrelated to previous hatching success or other factors, suggesting that changes in habitat quality and migration between populations were important in regulating population size. Recent extensive meadow restoration did not seem to aid the Northern Lapwing population; birds continued nesting on tillage even though most nests were destroyed by farming activities. A relatively high relaying frequency improved hatching success, which was still lowest in the most preferred habitats (spring sown crops, total hatching success c. 30%). The few Northern Lapwings breeding in the least preferred habitats (meadows and cultivated grassland) had a better hatching success (> 70% total hatching success), suggesting that habitat selection was not determined by hatching success. From these results, recommendations are made for the management of Northern Lapwing (and associated species) populations on farmland.     

Factors affecting nest site selection and nesting success in the Common Eider Somateria mollissima

Nesting site selection and nesting success in Common Eiders Somateria mollissima were studied over a 3-year period (1991–1993) in the Mast River delta (58^o24'N, 94^o24'W), 40 km east of Churchill, Manitoba, Canada. Eiders preferentially nested on islands that had incubating Lesser Snow Geese Anser caerulescens caerulescens on them; this effect was also seen between years on the same islands. Eiders which nested on islands with geese had a reduced chance of having eggs taken by predators during egg-laying and had a greater chance of hatching once incubation had begun, independent of the number of other eiders nesting on the island. The distance to a goose nest was less in nests which did not lose eggs prior to incubation than in those which did, but there was no difference in the distance to a goose nest in eider clutches which did or did not hatch. Artificial eider eggs placed closer to goose nests had a lower probability of being predated than those placed farther away. Nests on islands farther up the river and farther from the mainland had higher nesting success, presumably because these nesting islands were inaccessible to Arctic Foxes Alopex lagopus.     

Breeding success and chronology of Wood Storks Mycteria americana in northern and central Florida, U.S.A.

The breeding success and chronology of Wood Storks Mycteria americana were studied at eight colonies in northern and central Florida during 1981–1985. Mean ± s.d. clutch size for all colony-years was 3.07 ± 0.56 (n = 2694 nests), with three-egg clutches (72%) most frequent. Mean clutch size among all colonies and years ranged from 2.73 ± 0.55 to 3.41 ± 0.61. Many colonies exhibited significant negative trends in clutch size with, hatching date because of a proportional decrease in four-egg clutches later in the season. Mean colony clutch size was not correlated with nest numbers, nesting density or mean hatching date within most years. Mean ± s.d. number of fledglings for all colonies and years was 1.29 ± 1.16 fledglings per nest (n = 2812 nests). Mean annual fledging rates in colonies ranged from 0 (colony failed) to 2.66 fledglings per nest. Most breeding failure occurred prior to egg hatching, and the second highest mortality occurred between hatching and 2 weeks of age. Four-egg clutches fledged more storks than three-egg clutches, which in turn were more successful than two-egg clutches. However, all clutch sizes showed similar fledgling per egg rates. The seasonal decline in productivity was associated proportionally with smaller clutch sizes later in the breeding season. An increase in mean hatching date was correlated with an increase in latitude. There was greater within-year breeding synchrony among colonies than interyear breeding synchrony within each colony. Breeding synchrony was not correlated with mean hatching date, latitude, longitude, nest numbers or nesting density.     

Factors affecting nesting success of a bird assembly in the central Monte Desert, Argentina

We estimated nesting success of a breeding bird assemblage in the central Monte Desert in four breeding seasons (1995–1999). We analyzed the effect of year, period within the breeding season, nest type, and nest location on daily survival rates (DSR). Averaged nesting success of passeriforms in natural habitats was very low (<20% on average, n=12 species). DSR tended to be lower during the egg-laying stage in Furnariidae, Rhinocryptidae, Mimidae, and Emberizidae. Tyrannidae had the highest DSR for all nesting stages and Emberizidae the lowest. Predation was the main cause of nest failure (>90% on average, n=12 species). DSR differed among years, being higher in the driest year (1995) and lower in the most humid year (1997). Nests initiated in the first half of the breeding season had higher DSR than those initiated in the second half. Closed nests had similar survival rates to open nests. DSR differed according to species of plant that supported the nest. Nest predation in the central Monte Desert may be an important selective pressure in birds' life history, which is in accordance with other results for South American temperate birds.     

Pair bond and breeding success in Blue Tits Parus caeruleus and Great Tits Parus major

Data from 939 nests of the Blue Tit Parus caeruleus and 1008 nests of the Great Tit P. major from nestboxes provided in superabundance in mixed forest study sites between 1976 and 2001 were analysed to examine the effects of mate retention on breeding success and the relationship between mate fidelity and site fidelity. Most birds retained their former partner (76% in Great Tits and 65% in Blue Tits). The probability of a pair divorcing was affected by male age in Great Tits, divorce being more likely in pairs with first‐year males. Great Tit pairs breeding together for a second season bred earlier, but had no higher breeding success than pairs breeding together for the first time. In Blue Tits laying date and start of incubation tended to be earlier in pairs breeding together for a second season, but hatching and fledging dates were not earlier than in other pairs. Great Tit pairs breeding together for two consecutive seasons bred earlier in the second season than in the first, but breeding success did not differ significantly between years. In both species, breeding performance did not differ between pairs that divorced after a season and pairs that stayed together. Thus breeding success did not determine whether a pair divorced or bred together again. Neither Blue Tits nor Great Tits improved their breeding performance through divorce. Blue Tit females even had fewer fledglings in the year after divorce than in the year before. Mate retention affected breeding site fidelity. Blue Tit females had greater breeding dispersal distances between consecutive years when re‐mating than when breeding again with the same mate. In Great Tits both males and females dispersed more when re‐mating than when retaining the former partner, suggesting that mate retention increased the chance of retaining the breeding site. In both species, breeding dispersal distances did not differ between pairs that divorced and pairs in which one mate disappeared. Because no major advantage of mate retention was evident, we suggest that mate retention evolved under different conditions than those found in study sites with high breeding densities and a superabundance of artificial nesting sites.     

Growth and decline of a penguin colony and the influence on nesting density and reproductive success

Colonial breeding is characteristic of seabirds but nesting at high density has both advantages and disadvantages and may reduce survival and fecundity. African penguins (Spheniscus demersus) initiated breeding at Robben Island, South Africa in 1983. The breeding population on the island increased in the late 1990s and early 2000s before decreasing rapidly until 2010. Before the number breeding peaked, local nest density in the areas where the colony was initiated plateaued, suggesting that preferred nests sites were mostly occupied, and the area used by breeding birds expanded. However, it did not contract again as the population decreased, so that nesting density varied substantially. Breeding success was related positively to the prey available to the breeding birds and negatively to local nest density, particularly during the chick-rearing period, suggesting a density-dependence operating through social interactions in the colony, possibly exacerbated by poor prey availability when the breeding population was large. Although nest density at Robben Island was not high, nesting burrows, which probably reduce the incidence of aggressive encounters in the colony, are scarce and our results suggest that habitat alteration has modified the strength of density-dependent relationships for African penguins. Gaining a better understanding of how density dependence affects fecundity and population growth rates in colonial breeders is important for informing conservation management of the African penguin and other threatened taxa.     

Combining Site Occupancy,Breeding Population Sizes and Reproductive Success to Calculate Time-Averaged Reproductive Output of Different Habitat Types: An Application to Tricolored Blackbirds

In metapopulations in which habitat patches vary in quality and occupancy it can be complicated to calculate the net time-averaged contribution to reproduction of particular populations. Surprisingly, few indices have been proposed for this purpose. We combined occupancy, abundance, frequency of occurrence, and reproductive success to determine the net value of different sites through time and applied this method to a bird of conservation concern. The Tricolored Blackbird (Agelaius tricolor) has experienced large population declines, is the most colonial songbird in North America, is largely confined to California, and breeds itinerantly in multiple habitat types. It has had chronically low reproductive success in recent years. Although young produced per nest have previously been compared across habitats, no study has simultaneously considered site occupancy and reproductive success. Combining occupancy, abundance, frequency of occurrence, reproductive success and nest failure rate we found that that large colonies in grain fields fail frequently because of nest destruction due to harvest prior to fledging. Consequently, net time-averaged reproductive output is low compared to colonies in non-native Himalayan blackberry or thistles, and native stinging nettles. Cattail marshes have intermediate reproductive output, but their reproductive output might be improved by active management. Harvest of grain-field colonies necessitates either promoting delay of harvest or creating alternative, more secure nesting habitats. Stinging nettle and marsh colonies offer the main potential sources for restoration or native habitat creation. From 2005–2011 breeding site occupancy declined 3x faster than new breeding colonies were formed, indicating a rapid decline in occupancy. Total abundance showed a similar decline. Causes of variation in the value for reproduction of nesting substrates and factors behind continuing population declines merit urgent investigation. The method we employ should be useful in other metapopulation studies for calculating time-averaged reproductive output for different sites.     

Piping plover habitat selection and nest success on natural,managed, and engineered sandbars

Loss of breeding habitat and nest predation have contributed to the decline of many shorebird species. The United States Army Corps of Engineers (USACE) initiated a piping plover (Charadrius melodus) habitat creation and augmentation program on the Missouri River in the summer of 2004. The USACE increased unvegetated sandbar habitat by depositing dredged material (engineered sandbars) and by clearing vegetation from existing sandbars (managed sandbars). We evaluated the effects of this increase in nesting and foraging habitat on habitat selection and nest daily survival rate (DSR) of piping plovers on Lewis and Clark Lake and the Gavins Point Reach of the Missouri River from 2005 to 2007 (n = 623 nests). Piping plovers selected engineered sandbars more often than expected based on area and selected natural and managed habitats less than expected based on area. Daily survival rate on engineered sandbars was significantly higher than on natural or managed sandbars (log odds: 2.50, 95% CI: 1.05–5.94). Thus, plovers' habitat selection may have increased their nesting success. Our results suggest that habitat augmentation may stave off declines in piping plover populations limited by insufficient habitat and low nesting success. © 2011 The Wildlife Society.     

Nest site characteristics, duration of use and breeding success in the Guillemot Uria aalge

The fate of all eggs laid by Guillemots Uria aalge in seven study areas on the Isle of May was recorded in 12 consecutive seasons. The average success at each site was related to its physical characteristics, bird density, position on the cliff and availability of suitable habitat for ticks. The numbers of neighbours and walls, type of site, slope where the egg was incubated and distance from the top of the cliff all had a significant effect on both hatching and breeding success. Potential tick habitat had no significant effect. Much variation in hatching and breeding success remained unexplained. Sites used when the colony was less than half its current size and most frequently in the period 1984–1995 were the most successful. Since an average Guillemot pair remains together at a site for only 3–4 years. the consistently high success of many sites over a period of 10–12 years suggests that the most used sites were occupied by a succession of high-quality birds.     

Island accessibility and distance from beach influence nesting success of Sooty Falcons Falco concolor in Oman

Colonial island‐breeding birds can be particularly vulnerable to anthropogenic disturbance, which can adversely affect their nesting success. We studied Sooty Falcons Falco concolor breeding on 10 ground‐predator‐free islands in the Sea of Oman during 2007–2014 and evaluated spatio‐temporal trends in the number of breeding pairs occurring on the islands and the factors influencing nesting success. The number of breeding pairs on the islands declined during the study, due mostly to the decline on accessible islands; the rate of decline on islands accessible to humans was double that on inaccessible ones. The number of nests with one or more eggs declined during the study period, and the percentage of nests with eggs that produced one or more chicks showed an increasing trend over time. Sooty Falcon nests located farther away from beaches experienced a significantly higher probability of nesting success than those located closer to beaches. Our results suggest that the number of breeding Sooty Falcons on the islands of northern Oman is declining and that human disturbance may be a contributing factor; this probably mirrors the situation in other parts of the breeding range of this species.     

Restoration and management for cliff‐nesting birds in Mediterranean mining sites: the Sand Martin case study

Habitat enhancement for birds is frequently implemented during mine site restoration. Cliff‐nesting birds often colonize anthropogenic environments such as mining areas (aggregate sites and quarries for aggregate and cement production). Mining activity can compromise breeding success, causing cliff‐nesting birds to depend on the management and restoration of mining areas. The objective of our study is to assess the importance of mine site habitats for Sand Martin conservation and reconcile mining activity with breeding success in Mediterranean environments. We studied Sand Martin breeding habitat preferences in mining areas at three spatial scales. At the mining site scale, we compared 10 mining sites with Sand Martin burrows with 19 mining sites without burrows. At the colony scale (vertical structures with colonies), we evaluated the relationships between the number of breeding pairs, number of burrows, and colony characteristics within 30 distinct Sand Martin colonies. At the burrow scale, we compared the characteristics of the available vertical structure with the areas used by Sand Martins. At the mining site scale, Sand Martins preferred more surface of water bodies, shorter distances to flowing water, older sites, and mining sites which produce aggregates instead of cement. At the colony scale, Sand Martins preferred southwest orientations and stockpiles to vertical extraction faces. At the burrow scale, birds preferred the most vertical areas of the face. Our results support the need for effective habitat restoration and improved management for more effective Sand Martin conservation within mining areas. Simple interventions can enhance habitat quality and conservation of cliff‐nesting birds.     

Estimating the abundance and hatching success of breeding Curlew Numenius arquata using survey data

Counts of individual Curlew and estimates of breeding pairs from ‘field-by-field’ surveys were highly correlated with the numbers of nesting pairs, as determined by intensive studies on 27 sites located on four grassland-dominated study areas. The mean count of individual Curlew over three standard survey visits to each site was used to estimate numbers of nesting pairs. This estimate exceeded the number of nesting pairs on all study areas (as assessed by intensive studies) by 12% but was more accurate than the maximum number of pairs estimated from the three survey visits on each site (the previous convention for estimating breeding pairs). Estimates of the number of pairs hatching chicks were assessed by recording alarm-calling Curlew during late survey visits. The maximum number of alarm-calling pairs was used to estimate the number of pairs hatching chicks, overestimating this by 54%. Three of the study sites were adjacent to extensive moorland which produced overestimates during surveys because moorland nesting birds fed and led broods onto these sites. Omitting these sites from consideration reduced the degree of overestimation to 1% for the number of pairs and 7% for the number of pairs hatching chicks.     

Supplementary feeding increases Common Buzzard Buteo buteo productivity but only in poor‐quality habitat

Temporal heterogeneity in the effects of food supply during the breeding season on the productivity of the Common Buzzard Buteo buteo was investigated in a supplementary feeding experiment. Pairs were fed artificially (1) before egg‐laying, (2) after chicks hatched and (3) continuously throughout the season, and compared with (4) unfed controls. Pairs fed before egg‐laying had marginally larger clutches than those not fed, but lay date, egg volume and weight, brood size and hatching success were unaffected. Territorial quality had far greater effects, with pairs nesting in low‐quality habitats (bog, scrub and semi‐natural grassland) laying later and having lower hatching success, smaller broods and fewer fledglings than those in more productive agricultural landscapes. Supplementary feeding after egg hatching neutralized the negative effect of poor habitat, resulting in fed birds having significantly more fledglings. This study emphasizes the importance of food availability when provisioning chicks in suboptimal habitats and has implications for the success of diversionary feeding in reducing game losses to Buzzards.