Nest location, clutch size and nest success in the Scarlet Ibis Eudocimus ruber

Breeding success and nest-site characteristics were studied during the 1996–1997 breeding season in a colony of Scarlet Ibises Eudocimus ruber in south-eastern Brazil to test the hypothesis that nest-site characteristics and clutch size affect nest success. Two nesting pulses produced young, the earlier being more successful. Predation accounted for most failures during the first pulse, wind destruction during the second. A third pulse with few nests produced no young. Adult Ibises abandoned nests when they lost sight of other incubating birds. Logistic regression analysis indicated that nest success during the first pulse was positively related to clutch size, number of nests in the nest tree and in the nearest tree, and negatively to the distance to the nearest neighbour. During the second pulse there were significant negative associations between success, nest height and distance to the fourth nearest nest, and a positive association between success and nest cover. The results agree with the 'selfish herd' hypothesis, indicating that nest aggregation may increase breeding success, but the nest-site characteristics affecting success can differ over the course of one breeding season.     

Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird

In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences in nest predation may only weakly correlate with differences in nest predator abundance. An ecological trap is at work in a farmland bird (Lanius collurio) that recently expanded its breeding habitat into open areas in plantation forests. This passerine bird shows a strong preference for forest habitat, but it has a higher nest success in farmland. We tested whether higher abundance of nest predators in the preferred habitat or, alternatively, a decoupling of nest predator abundance and nest predation explained this observed pattern of maladaptive habitat selection. More than 90% of brood failures were attributed to nest predation. Nest predator abundance was more than 50% higher in farmland, but nest predation was 17% higher in forest. Differences between nest predation on actual shrike nests and on artificial nests suggested that parent shrikes may facilitate nest disclosure for predators in forest more than they do in farmland. The level of caution by parent shrikes when visiting their nest during a simulated nest predator intrusion was the same in the two habitats, but nest concealment was considerably lower in forest, which contributes to explaining the higher nest predation in this habitat. We conclude that a decoupling of nest predator abundance and nest predation may create ecological traps in human-modified environments.     

Nest site selection by yellow-faced honeyeaters Lichenostomus chrysops

When choosing subsequent nest sites, species that produce multiple broods in a single breeding season have the option of dispersing from a site where they previously suffered depredation, i.e., a predator-avoidance tactic. In our study on yellow-faced honeyeaters Lichenostomus chrysops it was found that 89% of nest failures were attributed to nest depredation, the primary cause of reproductive failure. Pairs re-nested further from depredated nesting attempts than from successful nesting attempts and progressively higher above the ground as the breeding season progressed. Pairs nesting in dioecious Coprosma quadrifida plants only nested in non-fruiting male plants. Artificial nests were used to test the hypothesis that nest height and plant preferences were strategies to reduce the risk of depredation. There was no evidence that either higher nests or nests in non-fruiting C. quadrifida achieved reduced levels of depredation during 14 days of artificial nest exposure. Specific nest site characteristics were not found to be associated with nest outcome for either natural or artificial nests. Our study provides further evidence that species may choose a diverse range of nest sites in order to avoid predators from developing specific search images and then, following depredation, compensate by rapidly re-nesting away from the failed attempt.     

Nesting success of native and introduced forest birds on the island of Kaua‘i

Forests of the Hawaiian archipelago are a global hotspot for conserving avian diversity and contain among the world's most imperiled species. Demographic studies are necessary to determine primary causes of Hawaiian forest bird population declines. We conducted research on the nesting success of multiple bird families on the island of Kaua‘i, allowing us to investigate the importance of factors related to breeding biology on forest bird declines at a community scale. Our study included two Hawaiian honeycreepers, ‘anianiau Magumma parva and ‘apapane Himatione sanguinea, a native monarch flycatcher, Kaua‘i ‘elepaio Chasiempis sclateri, and one introduced species, Japanese white‐eye Zosterops japonicus. Data from 123 nests showed that nesting success ± SE, estimated using program MARK, was low for ‘apapane (0.23 ± 0.10), but did not vary substantially among our other study species (‘anianiau = 0.56 ± 0.09, Kaua‘i ‘elepaio = 0.63 ± 0.08, Japanese white‐eye = 0.52 ± 0.11). Causes of nest loss for 51 nest failures included nest predation (43%), unknown (25%), empty after termination with no signs of nest predation (e.g. eggshell or chick remains in nest, disheveled nest) (24%), and abandoned clutch or brood (4% each). Kaua‘i ‘elepaio suffered more than twice as many nest losses to predation compared to our other study species, but also had the highest nesting success; and, ‘apapane suffered least to nest predation, but had the lowest nesting success. Further, rates of nesting success derived in our study were relatively high compared to multi‐species studies in mainland tropics. Therefore, although nest predation accounted for the greatest proportion of nest failures, it may not be a cause of forest bird population declines in our system. We suggest that future demographic studies focus on post‐fledgling, juvenile, and adult survival, in addition to the importance of double‐brooding and renesting attempts on annual reproductive success.     

A novel use of passive integrated transponder (PIT) tags as nest markers

ABSTRACT.   Double-observer methodology requires independent collection of data to accurately estimate population parameters. Use of visual nest markers to facilitate matching, relocating, and monitoring nests as part of a double-observer study violates this assumption, but few reliable alternatives exist, especially when working with cryptic nests and high nest densities in homogeneous habitat. We used passive integrated transponder (PIT) tags to nonvisually mark the nests of ground-nesting birds at the Yukon Delta National Wildlife Refuge in western Alaska in a double-observer study of nest density. We marked 70 nests with PIT tags and naïve observers subsequently detected tags at 44 of 50 re-scanned nests (88% correct identification). Failed detections were likely due to either suboptimal tag orientation or tags falling through nest material, and such failures may be an inherent, but uncommon, feature of this nest-marking technique. PIT tags facilitated nest monitoring among independent observers, uniquely and reliably marked nests, provided a minimum of cues to potential nest predators, and allowed us to estimate densities in a double-observer framework while not violating assumptions. These tags should be useful in other studies of nesting birds where nonvisual, reliable nest markers are needed, and they provide a new tool for double-observer studies.     

Colony defence against ants inVespa

Summary On Ishigaki Island in southern Japan, despite the prevalence of ants in the study area, none of the failures of 54Vespa affinis (L.) colonies located could be directly attributed to attacks from ants. The long vestibule of theV. affinis embryo nest was not effective in preventing access to the nest by small species of ants.V. affinis andV. tropica (L.) females produce a substance which is repellent to ants. The substance is produced by the 6th and 7th abdominal sternal glands and is thought to be applied to the embryo nest petiole via the sternal brush. As the substance is produced by workers and queens during the entire life of the colony, it probably has a dual function.     

Relationship Between Nest Predation Suffered by Hosts and Brown-Headed Cowbird Parasitism: A Comparative Study

There are at least four main hypotheses that may explain how the evolution of host selection by avian brood parasites could be linked to nest predation among their potential hosts. First, selection may have favoured parasite phenotypes discriminating among hosts on the basis of expected nest failure. Second, parasitized nests may be more easily detected by predators and extra costs of parasitism may accelerate the evolution of host defences. Third, selection may have favoured predator phenotypes avoiding parasitized nests because parasitism enhances nest defence. Fourth, female brood parasites may directly or indirectly induce host nesting failures in order to enhance future laying opportunities. We collected data on brood parasitism and nest failure due to predation to test these hypotheses in a comparative approach using North American passerines and their brood parasite, the brown-headed cowbird Molothrus ater. Under the hypotheses 1 or 3 we predicted brood parasitism to be negatively associated with nest predation across species, whereas this relation is expected to be positive if hypotheses 2 or 4 are true. We demonstrate that independent of host suitability, nest location, habitat type, length of the nestling period, body mass and similarity among species due to common ancestry, species experiencing relatively high levels of nest predation suffered lower levels of cowbird parasitism. Our results suggest a previously ignored role for nest predation suffered by hosts on the dynamics of the coevolutionary relationships between hosts and avian brood parasites. Co-ordinating editor: Dr. F. Stuefer     

Survival rates, causes of failure and productivity of Skylark Alauda arvensis nests on lowland farmland

This paper analyses data from 995 Skylark Alauda arvensis nests found on lowland farms in southern England from 1996 to 1998. The majority of recorded nest failures were caused by predation except in agricultural grass, where trampling and agricultural operations were equally important. Nest survival rates varied between crop types, nests in cereals being around twice as likely to succeed as nests in grass or set-aside. In cereals, nest survival rates increased with increasing distance from the nearest tramline and declined over the course of the breeding season. Predator control also had a significant independent effect on nest survival rates. On one farm where many other factors were held constant, a highly significant increase in nest survival rates from 12.3% to 40.7% coincided with the introduction of intensive predator control, which also appeared to bring forward mean laying dates. Most environmental factors explaining significant variation in nest survival rates did so only at the chick stage. The mean number of chicks produced per nesting attempt was 1.26 in cereals, 0.78 in set-aside and 0.63 in grass, the differences being due primarily to variation in nest survival rates. Low densities of Skylark territories in cereal crops are not therefore the consequence of low breeding success at the scale of the individual nest and probably reflect limitations on the number of attempts made in a season. Measures taken to improve the attractiveness of cereal crops as a nesting habitat for Skylarks, and beneficial changes in grassland management, are likely to increase overall productivity.     

Impact of human activities on the reproduction of Hooded Vultures Necrosyrtes monachus in Burkina Faso

During the last decades, the critically endangered Hooded Vulture Necrosyrtes monachus has strongly declined across its African range. Although direct persecution has been suggested as a major cause of this decline, little is known about the impact of humans on reproductive output in West Africa. We studied the impact of human activities on the reproductive output of Hooded Vultures in the Garango area of Burkina Faso. Twenty and 56 nesting attempts were monitored, respectively, during the breeding season in 2013/14 and 2014/15, to determine reproductive success and identify causes of nest failure. Annual breeding success varied between 0.68 and 0.71 chicks fledged per breeding pair per year and productivity was assessed at 0.57 chicks fledged per territorial pair in 2014/15. The main threats imposed by humans were poaching of eggs, chicks and collection of nest materials, leading to 20% (13 out of 64 breeding attempts) of nest failures over the two years. An additional important reason for nest failure was the pruning and (partial) cutting of nest trees. Despite this high level of human interference, we found that Hooded Vulture nest success increased with proximity to human settlements, probably because breeding vultures benefit from protection by people against persecution and disturbance.     

Effects of nestboxes on the breeding biology of Southern House Wrens Troglodytes aedon bonariae in the southern temperate zone

Nestboxes are known to increase clutch size, enhance breeding success and affect the social mating system of several cavity nesters. Although in recent years various cavity nesters have been studied in nestboxes in South America, the effects of boxes on the biology of the study species are unknown. We evaluated the effects of nestboxes on the breeding biology and social mating system of Southern House Wrens Troglodytes aedon bonariae by comparing birds breeding in nestboxes and tree cavities in two cattle ranches in Buenos Aires Province, Argentina. Southern House Wrens nesting in boxes had higher breeding success but, contrary to studies on the temperate zone, we did not find differences in clutch size between Wrens breeding in nestboxes and tree cavities. The main causes of nest failure in tree cavities were nest predation and flooding of the cavity (70 and 23% of the failures, respectively) while in nestboxes predation and desertion were the most important causes of failure (38 and 34% of the failures, respectively). The social mating system of Southern House Wrens is monogamy with biparental care, and neither was affected by the boxes. Males did not attract secondary females to additional nestboxes; however, nestboxes are safer breeding sites than tree cavities, and females seemed to prefer males with nestboxes on their territory. These results suggest that nest quality alone might be not enough for secondary females to accept polygyny.     

Costs of large communal clutches for male and female Greater Rheas Rhea americana

The breeding system of the Greater Rhea Rhea americana is almost unique among birds as it combines harem polygyny and sequential polyandry, with communal egg-laying and uniparental male care. In this species, large communal clutches (more than 30 eggs) are rare and have a lower hatching success than smaller clutches. Here we analyse the proximate causes of hatching failures and the costs of large communal clutches (and therefore the costs of extensive polygyny) for males and females. We evaluated if length of the nesting period, egg viability, egg losses during incubation and male parental activity at the nest were affected by clutch size. We also evaluated if chicks hatched from large clutches have a lower survival during the first 2 months after hatching. Large clutches had longer nesting period and lower hatching success, mainly as a result of bacterial contamination of the eggs and increased hatching asynchrony. In addition, large clutches tended to lose more eggs as a result of accidental breakage or predation. Male activity at the nest and chick survival were not related to clutch size. Low hatching success, nest predation risk and energetic costs associated with large clutches penalize females that join large harems and males that accept additional eggs into the nest.     

Traditional versus non-traditional nest-site choice: alternative decision strategies for nest-site selection

In order to understand habitat selection, it is important to consider the way individual animals assess the suitability of a future reproductive site. One way of investigating mechanisms (such as those involved in nest site selection) is to examine breeding success and habitat characteristics in terms of animals returning to a place where they have already reproduced and using the same location over successive years or searching for new alternatives. This approach seems especially suitable for testing recent hypotheses suggesting that nest site selection is an integrative process that includes the use of social information (e.g. past breeding success of conspecifics). Determining the factors that elicit conservative or innovative behaviour regarding nest-site selection could be important for improving our understanding of habitat selection decisions in animals. More than half of the nests of the long-distance migratory lesser grey shrike Lanius minor, are built in the same or neighbouring trees. We found no evidence that habitat characteristics influence nest-site tradition. On the contrary, social information in terms of the presence of conspecifics and past reproductive success in terms of complete nest failures due to nest predation (but not detailed information such as variation in fledgling number) influenced nest-site tradition. Hence, social information and past reproductive success may play a role in nest-site choice in this species. Our results further demonstrate that previous experience with a nest site does not appear to be beneficial.     

The breeding biology of the endemic Berthelot's Pipit Anthus berthelotii in a harsh oceanic island environment (Tenerife,Canary Islands)

We describe the density, breeding and foraging ecology of the Berthelot's Pipit (Anthus berthelotii), an endemic passerine to the Atlantic islands, in the semi-arid coastal scrub of Tenerife. Furthermore, we analyse the effects of temperature and rainfall in the onset of reproduction and the behaviour (nest site and foraging site selection). The average density of the Pipit (using DISTANCE methodology) in the semi-arid coastal scrub was 7.1 birds 10ha^?1, and the overall density estimate in grassland was 3.3 birds 10ha^?1. The Pipit bred early (mean average first-egg laying date 12 February) and in response to rainfall (but not temperature). By the Mayfield method, the probability of the nests surviving the egg stage was 0.77 and of and the nests surviving the chick stage 0.67 — assuming an incubation period of 13 days and a chick stage of 12.5 days — based on the European average for the similar-sized Meadow Pipit Anthus pratensis. Overall nest survival pooling stages were 0.51. The Pipits had a low clutch size (3.3 eggs, range of 2–4). Nest damage by heavy rainstorms was the major cause of nest failures (three out of five failures). The Pipits nested preferentially in grass with relatively low densities of Euphorbia balsamifera bushes. Birds selected grassy areas as their main foraging site but also preferred to forage on large rocks during nesting: caterpillars were the main food items (14 out of 17 prey captures).     

Increased nest predation in a declining and threatened Temminck's Stint Calidris temminckii population

We measured nesting success of the Temminck's Stint Calidris temminckii along the Finnish Bothnian Bay coast during 19 breeding seasons (1983–2001) and conducted a population census (1999–2002). We found 105 pairs, showing a marked decline from the previous survey (170 pairs 1987–95). Of the 424 'known-fate' nests, 47% hatched. Depredation caused 79.9% of the nest losses. Nesting failures increased from 1983–91 to 1992–2001 owing to a rise in nest predation. The proportion of failed nests that failed because of predation rose from 48.9 to 87.7%. When only depredated nests were considered as losses, Mayfield nest survival probability over the incubation period dropped from 69 to 31% (461 nests). This pattern emerged both in man-made and in natural habitats. Survival probability was independent of habitat type (natural vs. man-made). In an experiment involving videotaping of dummy nests, Common Gull Larus canus and Ruddy Turnstone Arenaria interpres were found to be the most important egg predators.     

Effects of Shiny Cowbird Molothrus bonariensis parasitism on different components of House Wren Troglodytes aedon reproductive success

Avian brood parasites, including cuckoos and cowbirds, have multiple negative effects on their hosts. We analysed the effects of Shiny Cowbird Molothrus bonariensis parasitism on different components (e.g. egg losses, hatching success, chick survival and nest abandonment) of House Wren Troglodytes aedon reproductive success. We also conducted an experiment to discriminate between two mechanisms that may reduce hatching success in parasitized clutches: lower efficiency of incubation due to the increase in clutch volume and disruption of host incubation by the early hatching of Cowbirds. Egg puncturing by Shiny Cowbirds reduced host clutch size at hatching by 10–20%, and parasitized nests had a decrease in hatching success of 40–80%. Egg losses and hatching failures were positively associated with the intensity of parasitism. Brood reduction was greater in parasitized nests, but the growth rate of the chicks that fledged was similar to that in unparasitized nests. The combined effects of egg losses, hatching failures and brood reduction decreased the number of fledged chicks by 80%. In addition, egg puncturing increased the likelihood of nest abandonment by Wrens. Experimental data showed that hatching failures occurred when there was a combination of: (1) an increase in the volume of the clutch by the addition of the Cowbird egg without removal of host eggs, and (2) the addition of the Cowbird egg before the onset of incubation. This was relatively common in House Wren nests, as Cowbirds generally parasitize before the onset of incubation. Our results indicate that Shiny Cowbird parasitism imposes a major impact on House Wrens, as it affects all components of the Wren's reproductive success.     

Biotic and abiotic factors affecting survival of early life history intervals of a stream-dwelling sunfish

Synopsis Biotic interactions, such as competition and predation, and abiotic events, such as floods, both have important consequences for organisms inhabiting warmwater streams. Empirical studies can lead to better understanding of how these factors interact to affect distinct life history intervals of stream fishes. Survival of eggs, embryos and larvae in nests of longear sunfishLepomis megalotis was monitored in a section of Jordan Creek for four years. During two years characterized by low, relatively stable flow, nest failures could be attributed to biotic interactions. During two years with more variable flow, most brood losses occurred during floods. Flooding led to nest desertion and loss of offspring regardless of nest location. The number of nests constructed tended to be lower during years with more variable flow. The proportion of nests with successful broods did not differ between colonial and solitary nests. Variation in flow regime modifies the importance of biotic effects on survival of early life history intervals of longear sunfish.     

The common cuckoo Cuculus canorus and its cavity nesting host, the redstart Phoenicurus phoenicurus: a peculiar cuckoo-host system?

We examined redstart Phoenicurus phoenicurus populations over a period of fifteen years to study interactions between the cuckoo Cuculus canorus and its cavity-nesting host. Over 380 redstart nests were checked and more than 100 cuckoo eggs were found during the study period. The average parasitism rate was 20%. The cuckoos' breeding success was extremely low, only 18 chicks surviving to the fledgling stage. When redstarts were parasitized experimentally with artificial cuckoo eggs, they rejected eight percent of mimetic eggs and 44% of non-mimetic eggs. We were not able to record any rejection of the real cuckoo eggs. However, about 30% of the real cuckoo eggs were found outside the redstart's nest cup. This could be the result of laying failures by the cuckoo, rather than of a strong rejection behaviour by the redstart. We suggest that redstarts' cavity nesting itself was a factor that reduced the cost of the parasitism dramatically. Firstly, it makes it difficult for the female cuckoo to lay her egg correctly in the nest and secondly, it is more difficult for the cuckoo chick to evict the host's eggs or nestlings effectively from the nest. Only 54% of the cuckoo chicks were able to evict all the host eggs or chicks from the nest. When reared in mixed broods, cuckoo chicks survived only in every second case to fledgling age, while at least one redstart chick from every brood managed to leave the nest.     

Nest success and cause-specific nest failure of grassland passerines breeding in prairie grazed by livestock

Livestock grazing is a widespread source of habitat modification, and may affect populations of ground-nesting grassland birds by influencing rates of nest failure. Nesting attempts can fail for various reasons, and determining risk of failure from specific causes associated with livestock grazing would enhance development of range management practices in areas managed for threatened grassland bird populations. Domestic livestock may influence nest failure by affecting vegetation structure, numerical or functional responses of predators, or directly by trampling nests. We hypothesized stocking rate may influence nest fate because it affects the amount and distribution of remaining vegetation, and the number of large herbivores to which nests are exposed. In 2007 and 2008, we evaluated nest fates for savannah sparrows and horned larks under 4 stocking rates experimentally applied in 40-ha paddocks in northeastern Oregon, USA. In addition to stocking rate, we evaluated variables such as vegetation structure and predator abundance and activity to help clarify mechanisms responsible for nest failure. We used a discrete competing risks framework to estimate daily probability of nest survival and failure from specific causes. These algorithms, implemented in a stand-alone graphical user interface-driven model, allow incorporation of covariates within an information theoretic approach to model inference. Although stocking rate influenced vegetation structure, the only nest failures related to stocking rate were from trampling. Trampling events were too infrequent to test for treatment effects (only 1 nest of each species), but occurred in the moderate and high stocking treatments. Additional variables were related to variation in nest failure from predation, but we found no support for the hypothesis that these causes of failure were affected by stocking rate. For savannah sparrows, daily probability of nest success (95% CI) = 0.97 (0.96–0.98); predation = 0.018 (0.008–0.028); and trampling = 0.001 (0.000–0.004). For horned larks, daily probability of nest success = 0.96 (0.95–0.98); predation = 0.029 (0.012–0.045); and trampling = 0.003 (0.000–0.007). Our results suggest grasslands managed for livestock may generally be compatible with grassland songbird conservation, at least for the species and stocking rates examined here. The most effective conservation strategies for improving nest success will involve decreasing risk of nest predation. However, we found no evidence that management of stocking rate is an effective method for doing so. © 2012 The Wildlife Society.     

Nesting in an uncertain world: information and sampling the future

Seasonal fecundity is strongly influenced by the number of nests attempted (including renests following nest failure) in a season. This number is often assumed to be set by the length of the breeding season or through some predetermined maximum. Instead, the decision to renest likely results from a cost–benefit analysis honed by natural selection where the ultimate components of fitness, i.e. reproduction and survival, tradeoff with one another. Moreover, reproductive decision making should not occur in an information‐vacuum. In a world where habitat quality (i.e. likelihood of nest success) is uncertain females should use nest failures to update the probability their renest nest will succeed, and this estimate in turn can affect the decision to renest. We develop a model of renesting behavior based on these conceptual ideas using the framework of statistical decision theory (SDT) and the process of Bayesian updating. We assume that renesting incurs 1) a cost to future reproductive success and 2) a reduction in expected reproductive success for each successive replacement nest. We show, all else equal, birds should curtail renesting with (1) increased residual reproductive success, (2) increased cost to future reproduction, (3) declines in current reproduction with successive attempts, and (4) increasing nest predation rates. We also explore several ecological implications of the model. First, uncertainty in habitat quality and the process of information updating, based on nest outcomes, link changes in the quality or proportion of one habitat type to the behavior in the other habitat. Second, females may use their estimate of habitat quality, based on a sample of nesting attempts, to decide whether to return or disperse to a new site between years. We compare this to the win‐stay: lose‐switch rule for dispersal and discuss the implications for population dynamics.     

Poor reproductive success of Gray Vireos in a declining California population

Since the 1940s, populations of Gray Vireos (Vireo vicinior) in California have collapsed, presumably because of parasitism by Brown‐headed Cowbirds (Molothrus ater). In 2012 and 2013, we studied the vireo's nesting ecology to assess factors affecting two of California's largest remaining populations in the chaparral of San Diego County. Nest success was extremely low, with a model‐averaged probability of nest survival of only 0.08 (N = 95). More nest failures were due to predation (83%) than to cowbird parasitism (13%). Video‐recording at 30 nests revealed that California Scrub‐Jays (Aphelocoma californica) were the most common nest predator (67%). Of eight variables tested, height of shrubs surrounding the nest had the strongest negative influence on nest survival, but was more strongly correlated with cowbird parasitism than with jay predation. Despite frequent renesting, seasonal productivity was well below the level required to sustain a population, especially in northern San Diego County where we found no Gray Vireos at six of seven sites where they had been present from 1997 to 2001 and where cowbird parasitism was more frequent. The vireo's continuing range collapse contrasts with recent climate‐change models predicting a range expansion, highlighting the importance of demographic studies. Low nest success is likely contributing to population declines in California, and the additive effect of cowbird parasitism suppresses productivity. Conservation of Gray Vireos in California will likely require development of alternative approaches to cowbird and scrub‐jay control appropriate to sites widely scattered in rugged chaparral.