Southern fiscal strangler

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Southern fiscal strangler
Southern fiscal strangler

Southern fiscal strangler

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Superfamily : Corvoidea
Family : Shrike (Laniidae)
Genre : Real strangler ( Lanius )
Type : Southern fiscal strangler
Scientific name
Lanius collaris
Linnaeus , 1766

The southern fiscal shrike ( Lanius collaris ) is a songbird from the genus of the real shrike ( Lanius ) within the family of the shrike (Laniidae). The southern fiscal strangler was removed from the Lanius collaris complex in 2011 and placed in species rank. Despite the very great morphological similarity to the sister species , the Northern Fiscal Shrike , there are very clear genetic differences between these species. The black-and-white drawn bird with the striking white V-markings on the back is up to 23 centimeters long and slightly smaller than the northern gray shrike , but much larger than a red backed shrike .

The southern fiscal strangler is very common in southern Africa . The species lives in different, moderately moist to extremely dry habitats . It needs bushes, trees, termite mounds , fences or electricity pylons as seats and the lowest possible vegetation. The southern fiscal strangler is increasingly penetrating settlements and cities, inhabiting agricultural land, and opening up new habitats along roads and the power pylons that accompany them. The species is distributed from sea level to heights of over 3000 meters.

The southern fiscal strangler is an opportunistic hunter who chases after any animal it can overpower. Arthropods make up the majority of the diet.

Lanius collaris is a resident bird. Outside of the breeding season he wanders around in small areas; vertical migration has also been observed. He lives singly or in pairs. At least during the breeding season, a pair will claim territory.

The species , of which 4–5  subspecies are described, belongs together with the Northern Fiscal Shrike to the Lanius collaris - super-species . The extent to which other stranglers should also be included in this species group ( rust -mantled shrike , Mackinnon shrike , São Tomé shrike ) is the subject of current research.

In contrast to most of the other species of the genus Lanius , the southern fiscal strangler has adapted very well to human proximity, is widespread and abundant locally. It is not listed in any hazard level.

Appearance

Southern fiscal shrike, female of the subspecies L. c. pyrrhostictus
Males of the subspecies L. c. subcoronatus
Young bird of the nominate form.
The rust-red flanks, the light-edged wing covers and wings as well as the recognizable face mask are clearly visible

The southern fiscal strangler is a medium-sized, long-tailed strangler with a striking black and white drawing with a completely black head and neck. The size of the individual subspecies is between 21 and 23 centimeters with a weight between 24.7 and 54 grams, with the largest and heaviest individuals being found at high altitudes. The differences in measurements taken at the same time of year and within the same subspecies were considerable: birds from Durban near sea level weighed an average of 32 grams, those from Harrismith at 1,800 meters above sea level 52 grams. In the seated bird, the V-shaped shoulder and back markings are particularly noticeable and distinctive, while in the flying bird the sickle-shaped white wing fields, the light gray rump and the white outer feathers of the tail are additional .

The head, neck and upper back are jet black. The shoulder girdle is white, the rump whitish-gray to light gray. The subspecies L. c. subcoronatus is characterized by a broad white stripe above the eyes , L. c. marwitzi has a narrow, sometimes interrupted, over-eye stripe. The wings are black on the top and dark slate gray on the underside. The white hand wings at their base form a not always clearly recognizable white wing field in the sitting bird, which is very conspicuous as a sickle-shaped marking in flight. The middle feathers of the, in contrast to the representatives of the northern group, somewhat shorter and wider, stepped tail are completely black, the outer feathers white. Towards the middle, some control feathers have white, often teardrop-shaped inclusions of varying degrees. The entire underside is white or gray-white; Fine dark corrugations can be seen on the flanks, especially in the case of individuals that have just been colored. The mighty hooked bill is black, as are the legs. The iris of the eyes is blackish brown.

Males and females are colored very similarly. The black parts of the female plumage are less saturated, rather very dark black-brown. It is characterized by a puffy, reddish-brown feather section on the flanks, which is often hidden under the wings. Females are insignificant, cannot be evaluated by field ornithology, and are smaller and lighter than males. Juveniles have a dull brown or gray-brown, finely dark corrugated top, with the already white shoulder area also being black or brown. The head and neck are more rusty brown. The black face mask typical of a strangler, which is covered by the black of the head of the adult bird, is recognizable as a dark area. The matt white underside has fine dark waves, sometimes also spots, the flanks have a reddish brown air in both sexes. The wing field is matt white, often isabel colored . The large arm covers have a light brown border, a feature that is often recognizable even after the first post-breeding moult. Juveniles in the northern group differ significantly from those in the southern group. The former are more reddish-brown and have a significantly more intense wave.

Occasionally, partial albinos have been observed.

Mauser

Juveniles begin to moult into their first adult plumage around three months of age . In many regions the time of this moult is between January and July. It is a complete moult that most 6-7 month old individuals have completed. The light edges of the large arm covers, occasionally also rust-brown feather areas on the flanks, can occasionally be seen even after the second total moult. Adult birds molt their entire plumage once a year after breeding. The time of the moult varies according to the regionally different breeding mines, but is mostly in the southern late autumn and winter months.

Vocalizations

The species has a large number of different calls, some of which are used very selectively in narrowly defined situations (e.g. warning of flight enemies). The most frequent call, which can be in a territorial as well as a sexual context, is a moderately loud, mostly two-syllable, multiple -stringed , croaking, cher-chyat ... , which is modulated differently and is usually stressed on the second syllable. Quieter , less harsh chüö-chjüt calls are clearly sexually motivated . Hoarse, often garish khriiie ... , or almost avocal chhiii ... series of calls are both aggressive sounds and undifferentiated alarm calls. A single Tsche can often be heard between the partners as a contact call , sometimes accompanied by soft whistling tones. The singing is a quiet, individually very different chatter, mixed with pressed sounds, whistles and various phrases from other birdsong and different ambient sounds.

distribution and habitat

Distribution of the Lanius collaris - super species
red: Northern fiscal strangler
green: Southern fiscal strangler
dark blue: Reichenow crusher
Habitat of the species in a savannah near Pietermaritzburg
The Uluguru Mountains are the habitat of the subspecies L. c. marwitzi
L. collaris aridicolus occurs in damp areas of the Namib and in oases .

The southern fiscal strangler inhabits suitable habitats up to the extreme northeast of the country in the Republic of South Africa , almost all of Swaziland and Lesotho , the extreme south of Mozambique , with the exception of the north-west and south-east large parts of Zimbabwe , the south and the north of Botswana, split up into islands , the extreme south of Angola and all of Namibia except for the northeast and most of the desert areas . The subspecies L. c. marwitzi in several distribution islands in the mountain regions of southwest, central and northeastern Tanzania . The species does not breed in the central Kalahari and the southern fiscal strangler is also rare in the Kruger National Park .

The distribution areas of the northern and southern groups come close to each other in some regions, but only overlap north of Lake Malawi , where L. humeralis capelli and L. collaris marwitzi occur in the same region, but largely separated, sympatric . There were evidently hybrids observed, but the information is about contradictory.

In this both topographically and climatically heterogeneous distribution area, the species is able to use a multitude of different habitats and shows a strong willingness to colonize landscapes that have been changed by humans. It has become more common in many regions since the early 1900s. It is by far the most common type of strangler in southern Africa.

The southern fiscal strangler occurs in semi-deserts, acacia-lined savannas , in the grasslands of the eastern elevations used extensively for herd cattle, in the coastal bushland and bush-lined edges of marshes and populates the various types of landscape of the South African veld in varying degrees of density . It is a frequent breeding bird on the edge of agricultural land, in larger gardens, parks and on golf courses as well as on the edge of plantations. The species avoids deserts to a large extent, but can colonize foggy vegetation islands in the Namib in low density . L. collaris does not occur in pure forest areas , as well as in gallery forests along larger rivers. Pure grass savannahs are only populated in the peripheral areas and for a short time after extensive grass fires, if man-made structures provide stand guard rooms. Where other shrikes like the yellow-billed shrike or bokmakierie , or European migrants ( gray shrike , red-backed shrike ) are often differs L. collaris from most. This is probably one of the reasons why the southern fiscal strangler does not appear in the Kalahari.

The vertical distribution ranges from coastal regions near sea level to high altitudes of around 3000 meters. The highest nesting sites are in the Drakensberg and in the mountains of Tanzania.

Important requisites for a suitable territory are, in addition to sufficient food, perches on trees, bushes, termite mounds, pasture fences or telegraph poles and short or missing ground vegetation in order to be able to spot suitable prey.

The couples usually claim territory all year round. In agricultural as well as urban areas, the average area size was mostly one hectare. In an optimal habitat on a university campus in Lesotho, around 4 pair areas were found on 10 hectares. In habitats with a lower credit rating at higher altitudes and a low density of residences, the territories were significantly larger with up to 24 hectares. The main variables that determine the size of the area in addition to the food supply are the number and height of the available hides, the amount of precipitation, the altitude, the absence or presence of competitors for food and the body mass of the area owner. The smallest measured distance between two nests was 17 meters, but in the vast majority of cases it is many times greater.

Biological details

Most of the research on the Lanius collaris complex concerns the southern subspecies. Since 2000 in particular, a number of studies have been published that deal with many questions about the biology of the species. Many of the results were not yet available when the two standard works on Würger by Tony Harris and Kim Franklin or by Norbert Lefranc and Tim Worfolk went to press. Panov, to whom some of this work was already available, deals only marginally with the African shrike species. The Northern and Southern Fiscal Shrike are very similar both in behavior and morphologically; many of the research results given here for the southern species also apply to the northern species.

Food and subsistence

L. collaris is an opportunistic hunter who chases any prey it can overwhelm. Its diet consists mainly of insects and other invertebrates and, to a much lesser extent, of vertebrates . It is not certain whether vegetarian food is also regularly consumed , but figs on skewers have also been found. The composition of the prey varies seasonally and depends heavily on the size and weight of the shrike. The larger and heavier stranglers of the high altitudes prey significantly more vertebrates than the lighter individuals in the lowlands. The size of most prey animals is about two to three times the beak length (about 2 -5 centimeters), but the species can also beat significantly larger animals. In quantitative terms, vertebrate prey can be up to around 10%, but in relation to the biomass captured, its share is much higher. Occasionally, southern fiscal stranglers also consume remains of human food and carrion.

L. c. subcoronatus perch on an antenna

Among the insects, representatives of the hymenoptera , beetles , and grasshoppers dominate . Real crickets and mole crickets , butterflies and caterpillars , dragonflies , ants and termites are less common . If locusts or termites appear in large numbers, they can temporarily become the main source of food. Populations in lower and more humid areas capture a not inconsiderable number of annelworms and millipedes , especially in the summer months . Occasionally captured spiders , ticks , snails and crabs are of no consequence . Vertebrates such as small songbirds and their nestlings , small rodents , lizards , young snakes and frogs do not play a major role in numbers, but are a very important source of food, especially in the winter months, due to the significantly higher energy yield compared to insect food. Only the large stranglers of the highland areas regularly prey on vertebrates.

Adult female with a captured cricket

Like most other species of shrike, the southern fiscal shrike is a hide hunter . He gains almost 90% of his food with this effective and energy-saving hunting method. Anything that towers above the surface by at least one meter can serve as a hide. Mostly these are trees or bushes, termite mounds, telegraph poles, power lines, light poles, pasture fences, but also pasture and wild animals. The preferred height depends on the height of the ground vegetation; the higher this is, the higher the seats have to be. If there is no or low vegetation, the raised hide is around 4 meters, in areas with higher grass cover it is 10 meters and above. With the height of the hide, the radius of the effective hunting distance also increases. With low waiting areas, the hunt success is greatest within about 10 meters, with higher waiting areas this optimal distance is extended to up to 15 meters.

If the shrike spies a prey, it slides from the hide and hits it on the ground. Small animals are eaten immediately, larger animals are brought to the hide and cut up there in the beak or, like falconry, with the claws. When there is excess food, prey is impaled in thorn bushes or on barbed wire, but this behavior is not practiced by the Southern Fiscal Shrike as much as some species of shrike in the Northern Hemisphere . Larger prey, especially vertebrates and worms, are occasionally impaled. The effectiveness of the attacks is high: around 45–80% of attack flights are successful.

In addition to this main hunting method, the southern fiscal strangler catches flying insects in the air. Although it is energy-intensive, flight hunts can briefly become the predominant type of hunting with swarming termites. Occasionally L. collaris also collects prey directly from substrate surfaces (tree trunks, branches, leaves).

behavior

Like all members of the genus, L. collaris is also diurnal. Its activity phase begins about an hour after daybreak and ends at dusk and earlier outside the breeding season. He spends the hottest hours of the day resting or busy with feathers in the shade and under cover of a tree or bush. Outside of the breeding season, most of the time is spent looking for food, resting and other comfort behaviors (plumage care, sunbathing, dust and water bathing) and maintaining the territory. During the courtship and breeding season, activities associated with pair formation, brood and boy care, and increasingly for agonistic actions, take additional time, so that rest periods, overall rest periods and time spent on comfort activities are significantly reduced. During the breeding season itself and in the first days of the nestling period, the female is largely occupied with the brooding and huddling of the chicks, while the time budget of the male is fully occupied with procuring food for himself, the female and the young as well as preserving the territory.

The species is largely territorial. Most of the time, the males occupy territories that become mating territories during the breeding season and often last for several breeding seasons. These territories are defended by both partners, but especially by the male, against conspecifics, other shrike species as well as against food competitors and potential breeding parasites. The behaviors that can be assigned to the demarcation and assertion of the area include sitting upright in exposed places at the area boundaries, usually accompanied by lines of chär- chjät, flying over the area in a slow, conspicuous fluttering flight, threats with ruffled feathers and slightly spread wings, which with greater aggression in the humpback position with beak threats and Schnabel squires passes. Pursuit flights and, in the extreme case, physical attacks represent the last stage of aggressive acts, although actual contact fights were only very rarely observed. The territoriality of unmated females outside the breeding season is unclear. Apparently they prowl around and only hold feeding grounds for a short time.

Breeding biology

In the Republic of South Africa, fresh broods were found in all months of the year except February. The main breeding seasons are, however, in the rainier and therefore also more nutritious months, namely between June and January in Zimbabwe, in the western parts of the Republic of South Africa in May and between July and December, or in April and between June and January in the east of the country. In the other distribution areas, the main breeding season begins with the onset of the main rainy season. Courtship and nest building of the subspecies L. c. marwitzi were found in December. Two annual broods are the rule, some pairs also breed three times a year. Occasionally, were box broods observed.

The pairing takes place very quickly. When a male sees an unmated female in his territory, he utters chüö-chjut-calls followed by an excited, chirping song (often accompanied by flapping wings and spreading the tail). The female answers with soft contact calls. As the female gets closer, the male immediately begins looking for prey. The handover of feed is followed by territorial and pursuit flights, showing a nest location and ritualized nest hollows and then very soon the first copulations. Most pairs stay together for the entire breeding season, some for several years. Change of partner within a breeding period also occurs. The nest is usually in bushes or trees at heights between 0.6 and 6 meters. A large number of tree and bush species can be used as nest carriers. The final nest location seems to be determined by the female, who is also somewhat more involved in nest building than the male. The nest is a fairly large, open bowl made of dry grass and twigs, often camouflaged on the outside with leaves, dandelion fruit bunches and other plants or even artificial materials. Some of the nests are quite open.

Feeding a young fledgling bird

The clutches consist of 3–4 cream-colored or beige eggs, especially around the middle ring-shaped brownish or olive-green spotted eggs. They are laid every day and only incubated or shaded by the female from the penultimate egg. During this time and in the first few days after hatching, the male feeds the female and chicks alone. However, the female occasionally leaves the nest to look for food herself. The young hatch naked and blind after 17 days. The entire clutch hatches within one or two days. In the first few days, the chicks are hoofed by the female and fed by the male, after which both parents feed. After 15 days the young are completely feathered and shortly afterwards leave the nest. For the next three months, the parents provide them with food in decreasing intensity, even if they have already started a second brood. With the beginning of moulting into the adult plumage, the young are driven from the parents' area.

There are only a few small studies on breeding success. Although it seems to be slightly higher than in Lanius humeralis , it is still very low at well below 30%. In successful broods, an average of two young fledged. The breeding success is minimized by unfavorable weather conditions, but above all by predation. A large number of nest predators threaten clutches and nestlings, while brood parasitism from cuckoos and other parasitic bird species plays only a minor role.

Systematics

In 2011, Jérôme Fuchs et al. in the Journal of Biogeography a study that confirmed on a molecular genetic basis what has long been suspected on the basis of behavioral and morphological findings, namely that several species are involved in the Lanius collaris species. Following these research results, the IOC separated the complex into two types: a northern group with Lanius humeralis as the nominotypic taxon and a southern group with Lanius collaris as the nominate form .

The southern group with 5 (4) subspecies is genetically homogeneous despite some clear morphological differences. In the fringes of the distribution zones of the individual subspecies (with the exception of L. c. Marwitzi ) there are often mixed breeds that produce offspring with the plumage characteristics of both parents.

  • Lanius c. collaris Linnaeus , 1766 : South Namibia, South Central and East South Africa, Swaziland, Lesotho and Maputo Province in southern Mozambique - described above.
  • Lanius c. pyrrhostictus Holub & Felzeln 1882 : Extreme NE of Botswana, southern Zimbabwe, Limpopo and Mpumalanga Province in the Republic of South Africa and Gaza Province and Mozambique. Very similar to L. c. collaris - overall more saturated colors on the top; Tail a little shorter and wider. Matt white underside. Distinct rust-brown flanks in the females.
  • Lanius c. marwitzi Reichenow , 1901 : Occasionally, with the name Reichenowwürger, it is understood as an independent species. Mountain regions of Tanzania. Conspicuous white, relatively narrow stripe above the eyes that extends from the base of the beak to behind the ear covers . Almost pure black top, gray rump. Outer tail feathers white, inwardly decreasing proportion of white, middle pair black. Females without reddish brown flanks.
  • Lanius c. subcoronatus Smith , 1841 : Southernmost Angola, Namibia, Botswana, southwestern Zimbabwe and northern part of the Republic of South Africa. Clearer, slightly wider over-eye stripe than L. c. marwitzi - otherwise like the nominate form.
  • Lanius c. aridicolus Clancey , 1955 : Foggy vegetation islands and oases in the Namib. Slightly smaller and duller in color than L. c. subcoronatus , hardly distinguishable from this and mostly regarded as con- specific.

Other subspecies such as L. c. predator and L. c. vigilans are not generally recognized.

Persistence and Threat

The species has been very well studied, especially in South Africa. It is by far the most common type of strangler in the country, the population of which is increasing, especially in habitats designed by humans. It is widespread outside such habitats. It has been able to expand its living space significantly in the last few decades. Due to its very large distribution area, the stable or increasing breeding population and the lack of current threats, the IUCN classifies the entire population of Lanius collaris as LC IUCN 3 1st svg(= least concern - not endangered).

The considerable natural losses due to weather influences, collisions with vehicles and natural enemies (especially various birds of prey and owls , crows and other stranglers , as well as snakes , house cats, crawling cats and monkeys , to a lesser extent as a result of brood losses due to brood parasitism by various cuckoo species ), can be well compensated by multiple broods. Direct persecution by humans has not yet played a role in limiting the population, but the increasing use of insecticides could have a negative impact on the population in the long term.

literature

  • Tony Harris, Kim Franklin: Shrikes & Bush-Shrikes. Including wood-shrikes, helmet-shrikes, flycather-shrikes, philentomas, batises and wattle-eyes. Christopher Helm, London 2000, ISBN 0-7136-3861-3 .
  • Norbert Lefranc, Tim Worfolk: Shrikes. A Guide to the Shrikes of the World. Pica Press, 1997, ISBN 1-4081-3505-1 .
  • Reuven Yosef & International Shrike Working Group (2016). Common Fiscal (Lanius collaris). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (downloaded from http://www.hbw.com/node/60490 on July 9, 2016)
  • Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, ISBN 978-954-642-576-8 .

Web links

Commons : Southern Fiscal Shrike ( Lanius collaris )  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Jérôme Fuchs, Timothy M. Crowe and Rauri CK Bowie: Phylogeography of the fiscal shrike (Lanius collaris): a novel pattern of genetic structure across the arid zones and savannas of Africa. In: Journal of Biogeography (J. Biogeogr.) (2011). Pp. 12-13
  2. ^ Atlas of Southern African Birds
  3. ↑ a b c d e f g h i T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 174.
  4. ↑ a b Jérôme Fuchs, Timothy M. Crowe and Rauri CK Bowie: Phylogeography of the fiscal shrike (Lanius collaris): a novel pattern of genetic structure across the arid zones and savannas of Africa. In: Journal of Biogeography (J. Biogeogr.) (2011). Pp. 1-13
  5. ^ BirdLife International. 2012. Lanius collaris. The IUCN Red List of Threatened Species 2012: e.T22705074A39383043. doi : 10.2305 / IUCN.UK.2012-1.RLTS.T22705074A39383043.en
  6. ↑ S. Soobramoney, CT and NJ Downs Adams: Morphological variation in the Common Fiscal Lanius collaris along on altitudinal gradient in southern Africa. In: Ostrich 2005, 76 (3 & 4); 130-141; P. 135
  7. ↑ T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, pp. 176-177.
  8. ↑ a b c d e f T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 173.
  9. ^ T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, pp. 173-174.
  10. ↑ Recordings at xeno-canto
  11. ^ A b c T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 175.
  12. ↑ Author's note: The Reichenow shrike, which some authors consider to be an independent species, shows only a very small genetic difference to Lanius collaris , so it is its subspecies.
  13. ↑ Jérôme Fuchs, Timothy M. Crowe and Rauri CK Bowie: Phylogeography of the fiscal shrike (Lanius collaris): a novel pattern of genetic structure across the arid zones and savannas of Africa. In: Journal of Biogeography (J. Biogeogr.) (2011). Pp. 9-10
  14. ↑ a b c Reuven Yosef & International Shrike Working Group (2016). Uhehe Fiscal (Lanius marwitzi). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (downloaded from http://www.hbw.com/node/60492 on July 11, 2016).
  15. ↑ a b Jérôme Fuchs, Timothy M. Crowe and Rauri CK Bowie: Phylogeography of the fiscal shrike (Lanius collaris): a novel pattern of genetic structure across the arid zones and savannas of Africa. In: Journal of Biogeography (J. Biogeogr.) (2011). P. 9
  16. ↑ S. Soobramoney, CT and NJ Downs Adams: territorial behavior and time budget of the fiscal shrike Lanius collaris along on altitudinal gradient in South Africa. In: African Zoology Vol. 39, No. 1, April 2004. p. 137
  17. ↑ a b c d e f Reuven Yosef & International Shrike Working Group (2016). Common Fiscal (Lanius collaris). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (downloaded from http://www.hbw.com/node/60490 on July 11, 2016).
  18. ↑ S. Soobramoney, CT and NJ Downs Adams: territorial behavior and time budget of the fiscal shrike Lanius collaris along on altitudinal gradient in South Africa. In: African Zoology 39 (1); (April 2004); P. 138
  19. ↑ Grzegorz Kopij: Breeding-season density of Fiscal Shrike (Lanius collaris) in Lesotho. In: Biological Lett. 2004, 41 (2); Pp. 77-85
  20. ↑ S. Soobramoney, CT and NJ Downs Adams: territorial behavior and time budget of the fiscal shrike Lanius collaris along on altitudinal gradient in South Africa. In: African Zoology 39 (1); (April 2004); Pp. 137-142
  21. ^ A b E. N. Panov: The True Shrikes (Laniidae) ... 2011, p. 198.
  22. ^ T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000.
  23. ↑ N. Lefranc and Tim Worfolk: Shrikes. A Guide to the Shrikes ... 1997
  24. ^ Claire Louise Devereaux: Ecological factors influencing the reproductive Ecology, Territoriality and Foraging Behavior of Fiscal Shrikes. Thesis submitted in fulfillment of the requirements for the degree of Master of Science, in the Department of Biology, University of Natal. (1999) 179 pages. P. 136
  25. ↑ S. Soobramoney, CT and NJ Downs Adams: Variability in foraging behavior and prey of the Common Fiscal Shrike Lanius collaris, along on altitudinal gradient in South Africa. In: Ostrich 2004, 75 (3): 133-140; P. 136
  26. ↑ S. Soobramoney, CT and NJ Downs Adams: Variability in foraging behavior and prey of the Common Fiscal Shrike Lanius collaris, along on altitudinal gradient in South Africa. In: Ostrich 2004, 75 (3): 133-140; Pp. 135-136
  27. ↑ S. Soobramoney, CT and NJ Downs Adams: Variability in foraging behavior and prey of the Common Fiscal Shrike Lanius collaris, along on altitudinal gradient in South Africa. In: Ostrich 2004, 75 (3): 133-140; Pp. 134-137
  28. ↑ a b c T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, pp. 174-175.
  29. ^ Claire Louise Devereaux: Ecological factors influencing the reproductive Ecology, Territoriality and Foraging Behavior of Fiscal Shrikes. Thesis submitted in fulfillment of the requirements for the degree of Master of Science, in the Department of Biology, University of Natal. (1999) 179 pages. P. 150
  30. ↑ S. Soobramoney, CT and NJ Downs Adams: Variability in foraging behavior and prey of the Common Fiscal Shrike Lanius collaris, along on altitudinal gradient in South Africa. In: Ostrich 2004, 75 (3): 133-140; Pp. 135-139
  31. ↑ S. Soobramoney, CT and NJ Downs Adams: Variability in foraging behavior and prey of the Common Fiscal Shrike Lanius collaris, along on altitudinal gradient in South Africa. In: Ostrich 2004, 75 (3): 133-140; P. 137
  32. ↑ S. Soobramoney, CT and NJ Downs Adams: territorial behavior and time budget of the fiscal shrike Lanius collaris along on altitudinal gradient in South Africa. In: African Zoology 39 (1); (April 2004); P. 140
  33. ↑ a b c T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 176.
  34. ^ Claire Louise Devereaux: Ecological factors influencing the reproductive Ecology, Territoriality and Foraging Behavior of Fiscal Shrikes. Thesis submitted in fulfillment of the requirements for the degree of Master of Science, in the Department of Biology, University of Natal. (1999) 179 pages.
  35. ^ Claire Louise Devereaux: Ecological factors influencing the reproductive Ecology, Territoriality and Foraging Behavior of Fiscal Shrikes. Thesis submitted in fulfillment of the requirements for the degree of Master of Science, in the Department of Biology, University of Natal. (1999) 179 pages. Pp. 42-49
  36. ^ Claire Louise Devereaux: Ecological factors influencing the reproductive Ecology, Territoriality and Foraging Behavior of Fiscal Shrikes. Thesis submitted in fulfillment of the requirements for the degree of Master of Science, in the Department of Biology, University of Natal. (1999) 179 pages. Pp. 51-65
  37. ^ T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, pp. 175-176.
  38. ^ Claire Louise Devereaux: Ecological factors influencing the reproductive Ecology, Territoriality and Foraging Behavior of Fiscal Shrikes. Thesis submitted in fulfillment of the requirements for the degree of Master of Science, in the Department of Biology, University of Natal. (1999) 179 pages. Pp. 65-67
  39. ↑ EN Panov: The True Shrikes (Laniidae) ... 2011, p. 225.
  40. ↑ World Bird Names IOC 6.2
  41. ↑ Grzegorz Kopij: Breeding-season density of Fiscal Shrike (Lanius collaris) in Lesotho. In: Biological Lett. 2004, 41 (2); Pp. 82-83
  42. ↑ LP Quinn, B, J. de Vos, M. Fernandes-Whaley, C. Roos, H. Bouwman, H. Kylin, R. Pieters and J. van den Berg: Pesticide Use in South Africa: One of the Largest Importers of Pesticides in Africa pdf engl.