Ficedula hypoleucaEuropean pied flycatcher(Also: pied flycatcher)

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Geographic Range

Pied flycatchers breed all over Europe, extending into the subalpine regions. They arrive on their breeding grounds in May and migrate to the tropical west African coast, between the equator and 15 degrees north, for the winter. (Coppack, et al., 2006; Lampe and Espmark, 2003; Siilkamaki, et al., 1997)

Habitat

Pied flycatchers winter on the tropical coast of west Africa. In the breeding seasons pied flycatchers are found in forests, and forest composition varies by region. In central Europe, pied flycatchers prefer high altitude beech and spruce forests. They are also found at middle altitude levels, where beech and spruce mix with deciduous forest. Breeding in the middle altitude zone brings them in contact with collared flycatchers (Ficedula albicollis), which prefer low altitudes and deciduous trees. These sister species are normally separated by altitude, tree species preference, and foraging strategy; pied flycatchers prefer foraging near the ground, while collared flycatchers prefer the canopy. However, these two species still produce hybrids at a rate of 2.6% where they co-occur. (Adamik and Bures, 2007; Coppack, et al., 2006)

In Finland, pied flycatchers prefer large patches of dense, old-growth forest containing deciduous trees and Scots pine (Pinus sylvestris). Territories with deciduous trees proved better in this case, since they provided more food. (Huhta, et al., 1998)

Physical Description

Pied flycatchers are small passerines, weighing about 13 grams. They are darker dorsally and lighter ventrally, with white bars on the dorsal sides of their wings. They often hold their wing tips lower than their tails, which is normal for flycatchers. Females and immature males are light brown ventrally and dark brown dorsally. The plumage of males darkens as they age, until they reach a jet black color. Male plumage reflects ultraviolet light. During nesting, brooding females have an incubation patch which can be used to determine sex. ("Pied Flycatcher Ficedula hypoleuca", 2009; Robinson, 2005; Roskaft and Jarvi, 1982; Siitari, et al., 2002; Winkel, 1998)

Male birds have white spots on their foreheads, just above their beaks. The size of these spots directly correlates with a male’s attractiveness to a female. The size also indicates the male’s immune competence, and larger patches are correlated with fewer trypanosome infections. Usually males are the only ones with white forehead patches, but in some populations females may have them as well. These populations are generally in the southern parts of their range, and the patch is a sign of ageing, rather than health. (Morales, et al., 2007; Sanz, 2001)

Insectivores, like pied flycatchers, generally have intermediate basal metabolic rates when compared to similar birds eating different diets. Temperate species average higher basal metabolic rates (BMR) than tropical species, and flighted birds are higher than flightless ones. There are other factors influencing the BMRof a species, including plumage color. Pied flycatchers average about 0.84 kJ/h in BMR. (McNab, 2009)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • male more colorful
  • Average mass
    13 g
    0.46 oz
  • Average length
    13 cm
    5.12 in
  • Average wingspan
    22 cm
    8.66 in
  • Average basal metabolic rate
    0.84 kJ/h cm3.O2/g/hr

Reproduction

Both monogamy and polygyny occur in this species. When a male has two mates, he usually keeps two separate territories, but sometimes both females will coexist in one territory, sometimes even on the same nest. Single females lay 5 to 7 eggs, two females laying together can produce double the eggs. Despite having so many eggs, however, females that nest together only average 1.1 more offspring than monogamous females. In bigynous systems with two territories, the primary female fares better than the secondary female, who may have been tricked into mating with an already paired male. The male usually provides more for his primary mate than the secondary mate, and sometimes he abandons his secondary mate altogether. (Huk and Winkel, 2006; Winkel, 1998)

Polygyny may also represent a cost to males. Polygynous males are more likely to have unhatched eggs. They are also more likely to be cheated on by one or both mates, causing them to expend energy raising chicks that aren’t theirs. (Lubjuhn, et al., 2000)

Secondary female mates may receive a benefit from mating with an already paired male in the form of good genes. This is consistent with the “sexy son” hypothesis and suggests that sons inherit their father’s attractiveness and get more mates, resulting in the same number of grandchildren as the primary female. There is no evidence of this "sexy son" hypothesis in pied flycatchers. Huk and Winkel (2006) found sons of polygynous males were more reproductively successful, but this was true only for sons of primary females, not secondary female mates. (Huk and Winkel, 2006)

Males use songs to attract females. Bright plumage and complex songs indicate better fitness, so they are preferred by females. Their plumage is even ultraviolet reflective to make it bright to the females’ eyes. One of the best and quickest ways to judge males in an area is to listen to their songs, since the best males arrived first and got the best territories. (Lampe and Espmark, 2003; Siitari, et al., 2002)

Males arrive first in breeding areas and set up their territories. They nest in holes or in nest boxes. They must defend their locations from other males, so they stay near the nest hole. Since they can’t move far from the nest hole without risking the loss of their spot, females are the ones who peruse available males and choose mates. Females generally choose older males first, who are identified by their jet black and white plumage instead of the brown, grey, grayish brown, and light black plumage of younger males. Older males are most likely to become polygamous. (Moller and Mousseau, 2007; Roskaft and Jarvi, 1982)

It appears pied flycatchers not only prefer to nest in boxes, but are more successful when they do. Females begin laying eggs one or two days earlier and lay more eggs when in nest boxes. Larger clutch size is probably due to greater space, since clutch size is correlated with the area of the bottom of the nest. They experience less predation, possibly because the entrance to the box is higher than the actual nest. In natural holes, the entrance may be closer to the nest, making contents easier to access. If given enough nest boxes, these birds will nest at densities up to 200 pairs per square kilometer. In natural nests with optimal settings, they will only nest at densities at a quarter of that level. Breeding success in nest boxes ranges from 72% to over 80%, whereas in natural nests success is usually 54%. (Nilsson, 1984)

Pied flycatchers lay 6 to 7 eggs which are 17 mm long and 13 mm wide. Eggs weigh about 1.7 grams, about 5% of that is the mass of the shell. The female incubates for 13 to 15 days. Young are altricial at hatching, with a thin covering of down. They fledge 16 to 17 days later. (Robinson, 2005)

  • Breeding interval
    Pied flycatchers mate once a year, beginning in May.
  • Breeding season
    Pied flycatchers breed from May into July.
  • Range eggs per season
    6 to 7
  • Range time to hatching
    13 to 15 days
  • Range fledging age
    16 to 17 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Some females will lay their eggs in another female’s nest. Intraspecific nest parasitism is rare for pied flycatchers, and females guard their nests vigorously to avoid having to raise a chick that is not their own. Females are most aggressive toward each other in the nest building and egg laying phases of their reproductive cycles. (Winkel, 1998; Yom-Tov, et al., 2000)

Some females reduce their clutch sizes by removing an egg. They place the egg on the rim of the nest, where it cools until the embryo is dead. Ejections most commonly occur after a particularly cold day. Females who eject eggs are more likely to overlap reproduction and moulting, two processes which require a lot of energy and are usually performed separately. Combining reproduction and moulting may indicate the female in question simply isn’t interested in reproduction as much as non-ejecting females. Other females who eject their eggs are either old (over four years) or have poor immune systems, both of which are physiological factors which make females less-than-ideal mothers. (Lobato, et al., 2006)

Brood size affects parental investment by determining how much food parents need to supply. Parents often can’t supply enough when they have too many young. Parents with large clutches make more visits to the nest, but they make fewer visits per nestling than parents with smaller clutches. They don’t bring more food per visit, so each nestling gets less to eat than nestlings in smaller clutches. When presented with too little food, nestlings invest their nutrients in growing muscle and bone, because deficits in these areas are hard to make up later, and they will neglect proper gut development, which can be made up later. Neglecting gut development results in a shorter gut and less absorption abilities, which worsens their undernourishment. (Wright, et al., 2002)

The eggs are blue-green, a color caused by biliverdin, a pigment and an anti-oxidant. The more biliverdin is present in the egg shell, the brighter the egg and the more maternal antibodies it contains. This is important because the better the hatchling's immune system is, the more likely it will grow up healthy and able to reproduce. Laying bright eggs is the female’s way of signaling to her mate that she is healthy and producing good eggs. Deeply colored eggs have young with better immune systems. Eggshells with high levels of immunoglobins even move into the ultraviolet spectrum. Males visit the nest and assess the color of eggs. Males spend more time provisioning young hatched from eggs with good coloring. Male contributions relieve some of the burden on females, allowing her to recover and regain her health after incubation. (Morales, et al., 2006; Moreno, et al., 2005; Moreno, et al., 2006)

Sanz (2001) performed an experiment in which he reduced the size of the white patch on mated males. He found males with smaller white patches (therefore, less attractive males) spent more energy bringing food to their young. The young grew larger than those of unaltered fathers, which shows a clear benefit from the extra provisioning. Females did not change their feeding habits regardless of the males’ attractiveness or effort. The extra effort could be caused by the male being aware he is less attractive and therefore less able to successfully solicit extra-pair copulations, so he invests his time more in parenting. (Sanz, 2001)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male

Lifespan/Longevity

Pied flycatchers can reproduce until they are 6 years old, few birds reproduce after that age. The oldest recorded bird was found in Finland, aged 10 years and 11 months old. (Robinson, 2005; Winkel, 1998)

  • Range lifespan
    Status: wild
    131 (high) months

Behavior

After fledging, young explore their natal territory and imprint on it. Each spring, they return to the same general area, though not the exact spot. Females disperse farther from their natal territory than males. Chernetsov et al. (2006) found males returned to sites about 4 kilometers from their home nest site and females choose territories about 6.5 kilometers from their home nest. In another study (Moller and Mousseau, 2007) birds were observed travelling an average of 14.3 kilometers from their natal site. Pied flycatchers are active during the day. (Chernetsov, et al., 2006; Moller and Mousseau, 2007)

Pied flycatcher migratory behavior can be explained by the clock-and-compass strategy. Rather than using a map, parental guidance, or landmarks, they determine the correct direction to fly using the earth’s magnetic field and constellations and fly until it’s time to stop. They migrate at night and cover between 100 and 125 kilometers each night. Because of wind, topography, navigation mistakes, and other errors, migration trajectories are shaped like a narrow parabola, with most birds staying on the intended trajectory and others deviating slightly. (Mouritsen and Mouritsen, 2000)

Home Range

Home range size of pied flycatchers is not reported.

Communication and Perception

Pied flycatchers can see in the ultraviolet spectrum and females use this ability to choose mates. Males also use ultraviolet reflection to visually inspect the eggs his mate has laid. Eggs that reflect in the ultraviolet spectrum receive more parental investment from male parents. Pied flycatchers also use song, plumage color, and egg color to send signals to each other. (Lampe and Espmark, 2003; Morales, et al., 2006; Moreno, et al., 2005; Moreno, et al., 2006; Siitari, et al., 2002)

Food Habits

Pied flycatchers often catch their prey in the air. They are insectivorous and eat many types of invertebrates, including beetles, spiders, and caterpillars. They also eat flies, ants, bees, and wasps, moths and their larvae. Individuals in populations in polluted areas eat more larvae and fewer moths and spiders than in populations in less polluted areas. (Eeva, et al., 2005; Huhta, et al., 1998; Marchetti, et al., 1998)

Interestingly, pied flycatchers are not fooled by eyespots on butterfly wings. They will attack butterflies with and without eyespots at equal frequencies. (Lyytinen, et al., 2003)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Groups of pied flycatchers respond to predators by mobbing them. Whichever bird spots the intruder will send out a mobbing call to alert the other flycatchers. If the intrusion is serious enough, several pied flycatchers will group together and harass the predator until it leaves. While this is a good strategy for large groups with many possible recruits for the mob, it can be dangerous for birds in less dense living situations. Predators like martens (Martes) may learn the mobbing call and respond to it, coming to attack the nests of birds while they are busy attacking the original intruder. (Krama and Krams, 2004; Krama and Krams, 2004)

Stoats (Mustela erminea), least weasels (Mustela nivalis), and martens (Martes) raid nests. Goshawks (Accipiter gentilis), Eurasian sparrowhawks (Accipiter nisus), and tawny owls (Strix aluco) prey on fledgling and adult pied flycatchers. (Selas and Steel, 1998; Selas and Steel, 1998)

Mobbing is reciprocal. When a bird hears the mobbing call, it may choose to assist or not. Assisting in mobbing behavior is dangerous, so some birds choose not to help their neighbors. However, birds who do not help in mobbing are significantly less likely to be helped if their nests are threatened. (Krams, et al., 2006)

Ecosystem Roles

Pied flycatchers are subject to a range of parasitic infections. The white patches on their foreheads and wings lack the protection of melanin, so those areas are more prone to breakage, bacterial infection, and lice infestations. Pied flycatchers carry infestations of mites and fleas. (Merino and Potti, 1996; Morales, et al., 2007)

Nestlings are parasitized by blow fly larvae (Protocaliphora azurea). Well-fed nestlings are more resistant to parasitism. Blood parasite infections increase in parents with large clutches. Haemoproteus balmorali affects males more, while Haemoproteus pallidus affects females. The increased infection rate is probably due to the birds spending their energy on feeding their young at a cost to their immune systems. (Merino and Potti, 1998; Siilkamaki, et al., 1997)

Pied flycatchers have a varying relationship with northern wood ants (Formica aquilonia). When they nest in trees containing these ants, their nests are at risk of predation from the ants. However, when there is another predator which may eat the nestlings, like Eurasian jays (Garrulus glandarius), pied flycatchers may choose to nest in trees with wood ants because they help to defend against jays. (Haemig, 1999)

Mutualist Species
Commensal/Parasitic Species
  • blood parasites (Haemoproteus pallidus)
  • blood parasites (Haemoproteus balmorali)
  • trypanosomes (Trypanosoma avium)
  • blow fly larvae (Protocaliphora azurea)

Economic Importance for Humans: Positive

Pied flycatchers eat the larvae of moths and other pests, including Eugraphe subrosa, Syngrapha interrogationis, Cerastis rubricosa, and Polia hepatica, which feed on plants in the genus Vaccinium, such as bilberry, cowberry, cranberry, and blueberry. Pied flycatchers also eat many other insects and spiders. ("Wikipedia", 2008; Selas and Steel, 1998)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of pied flycatchers on humans.

Conservation Status

Pied flycatchers have a massive range extending to about 10,000,000 square kilometers. Their population levels are also large, around 24,000,000 to 39,000,000 birds in Europe. Population trends haven't been carefully studied, but BirdLife International does not believe they are declining at a significant rate. Therefore, they are listed as "Least Concern" by the IUCN Red List. (BirdLife International, 2008)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Aqua Nara Dakota (author), Special Projects.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

magnetic

(as perception channel keyword). This animal has a special ability to detect the Earth's magnetic fields.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynous

having more than one female as a mate at one time

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

BirdGuides Ltd. 2009. "Pied Flycatcher Ficedula hypoleuca" (On-line). BirdGuides. Accessed January 07, 2009 at http://www.birdguides.com/species/species.asp?sp=137055.

2008. "Wikipedia" (On-line). Vaccinium. Accessed January 07, 2009 at http://en.wikipedia.org/wiki/Vaccinium.

Adamik, P., S. Bures. 2007. Experimental evidence for species-specific habitat preferences in two flycatcher species in the hybrid zone. Naturwissenschaften, 94: 859-863.

BirdLife International, 2008. "2008 IUCN Red List of Threatened Species" (On-line). Ficedula hypoleuca. Accessed January 07, 2009 at http://www.iucnredlist.org/details/147361.

Chernetsov, N., L. Sokolov, V. Kosarev, D. Leoke, M. Markovets, A. Tsvey, A. Shapoval. 2006. Sex-related natal dispersal of pied flycatchers: how far away from home?. The Condor, 108: 711-717.

Coppack, T., I. Tindemans, M. Czisch, A. Van der Linden, P. Berthold, F. Pulidos. 2006. Can long-distance migratory birds adjust to the advancement of spring by shortening migration distance? The response of the pied flycatcher to latitudinal photoperiodic variation. Global Change Biology, 14: 2516-2522.

Eeva, T., M. Ryoma, J. Riihimaki. 2005. Pollution-related changes in diets of to insectivorous passerines. Oecologia, 145: 629-639.

Haemig, P. 1999. Predation risk alters interactions among species: competition and facilitation between ants and nesting birds in a boreal forest. Ecology Letters, 2: 178-184.

Huhta, E., J. Jokimaki, P. Rahko. 1998. Distribution and reproductive success of the Pied Flycatcher Ficedula hypoleuca in relation to forest patch size and vegetation characteristics; the effect of scale. IBIS, 140: 214-222.

Huk, T., W. Winkel. 2006. Polygyny and its fitness consequences for primary and secondary female pied flycatchers. Proceedings of the Royal Society, 273: 1681-1688.

Krama, T., I. Krams. 2004. Cost of mobbing call to breeding pied flycatcher, Ficedula hypoleuca . Behavioral Ecology, 16 (1): 37-40.

Krams, I., T. Krama, K. Iguane. 2006. Mobbing behavior: reciprocity-based co-operation in breeding Pied Flycatchers Ficedula hypoleuca . IBIS, 148: 50-54.

Lampe, H., Y. Espmark. 2003. Mate choice in Pied Flycatchers Ficedula hypoleuca: can females use song to find high-quality males and territories?. IBIS, 145 (online): E24-E33.

Lobato, E., J. Moreno, S. Merino, J. Sanz, E. Arriero, J. Morales, G. Tomas, J. Martinez-de la Puente. 2006. Maternal clutch reduction in the pied flycatcher Ficedula hypoleuca: an undescribed clutch size adjustment mechanism. Journal of Avian Biology, 37: 637-641.

Lubjuhn, T., W. Winkel, J. Epplen, J. Brun. 2000. Reproductive success of monogamous and polygynous pied flycatchers (Ficedula hypoleuca). Behav. Ecol. Sociobiol., 48: 12-17.

Lyytinen, A., P. Brakefield, J. Mappes. 2003. Significance of butterfly eyespots as an anti-predator device in ground-based and aerial attacks. Oikos, 100: 373-379.

Marchetti, C., D. Locatelli, A. Van Noordwijk, N. Baldaccini. 1998. The effects of prey size on diet differentiation of seven passerine species at two spring stopover sites. IBIS, 140: 25-34.

McNab, B. 2009. Ecological factors affect the level and scaling of avian BMR. Comparative Biochemistry and Physiology, Part A 152: 22-45.

Merino, S., J. Potti. 1998. Growth, nutrition, and blow fly parasitism in nestling Pied Flycatcchers. Canadian Journal of Zoology, 76: 936-941.

Merino, S., J. Potti. 1996. Weather dependent effects of nest ectoparasites on their bird hosts. Ecography, 19: 107-113.

Moller, A., T. Mousseau. 2007. Birds prefer to breed in sites with low radioactivity in Chernobyl. Proceedings of the Royal Society, 274: 1443-1448.

Morales, J., J. Moreno, S. Merino, J. Sanz, G. Tomas, E. Arriero, E. Lobato, J. Martinez-de la Puente. 2007. Female ornaments in the Pied Flycatcher Ficedula hypoleuca: associations with age, health and reproductive success. IBIS, 149: 245-254.

Morales, J., J. Sanz, J. Moreno. 2006. Egg colour reflects the amount of yolk maternal antibodies and fledging success in a songbird. Biology Letters, 2: 334-336.

Moreno, J., J. Morales, E. Lobato, S. Merino, G. Tomas, J. Martinez-de la Puente. 2005. Evidence for the signalling function of egg color in the pied flycatcher Ficedula hypoleuca . Behavioral Ecology, 16: 931-937.

Moreno, J., J. Morales, E. Lobato, S. Merino, G. Tomas, J. Martinez-de la Puente. 2006. More colourful eggs induce a higher relative paternal investment in the pied flycatcher Ficedula hypoleuca: a cross-fostering experiment. Journal of Avian Biology, 37: 555-560.

Mouritsen, H., O. Mouritsen. 2000. A Mathematical Expectation Model for Bird Navigation based on the Clock-and-Compass Strategy. Journal of Theoretical Biology, 207: 283-291.

Nilsson, S. 1984. Clutch size and breeding success of the Pied Flycatcher Ficedula hypoleuca in natural tree-holes. IBIS, 126: 407-410.

Robinson, R. 2005. "BirdFacts: profiles of birds occurring in Britain & Ireland" (On-line). Pied Flycatcher Ficedula hypoleuca. Accessed January 07, 2009 at http://blx1.bto.org/birdfacts/results/bob13490.htm.

Roskaft, E., T. Jarvi. 1982. Male plumage colour and mate choice of female Pied Flycatchers Ficedula hypoleuca . IBIS, 125: 396-400.

Sanz, J. 2001. Experimentally reduced male attractiveness increases parental care in the pied flycatcher Ficedula hypoleuca . Behavioral Ecology, 12 (2): 171-176.

Selas, V., C. Steel. 1998. Large brood sizes of pied flycatcher, sparrowhawk and goshawk in peak microtine years: support for the mast depression hypothesis. Oecologia, 116: 449-455.

Siilkamaki, P., O. Ratti, M. Hovi, G. Bennett. 1997. Association between haematozoan infections and reproduction in the Pied Flycatcher. Functional Ecology, 11: 176-183.

Siitari, H., J. Honkavaara, E. Huhta, J. Viitala. 2002. Ultraviolet reflection and female mate choice in the pied flycatcher, Ficedula hypoleuca . Animal Behavior, 63: 97-102.

Winkel, W. 1998. Monoterritorial bigyny in the Pied Flycatcher Ficedula hypoleuca . IBIS, 140: 178-180.

Wright, J., C. Hinde, J. Fazey, C. Both. 2002. Begging signals more than just short-term need: cryptic effects of brood size in the pied flycatcher (Ficedula hypoleuca). Behavioral Ecology Sociobiology, 52: 74-83.

Yom-Tov, Y., J. Wright, C. Both. 2000. Intraspecific nest parasitism and nest guarding in the Pied Flycatcher Ficedula hypoleuca . IBIS, 142: 331-332.