Food habits and the survival and growth of nestlings in two sympatric kites (Milvus milvus and Milvus migrans)

Black and Red Kites Milvus migrans and M. milvus chase other raptors approaching their nests. The study of this behaviour during the post‐fledging period suggested that it reflects mainly, but not only, anti‐predator behaviour. The frequency of vigilance and aggressive chases decreased through the post‐fledging period as predicted by theoretical models of nest defence. Although predation risks were similar, Black Kites invested more time chasing intruders than did Red Kites. Black Kites, unlike Red Kites, chased away intruding juveniles, which may be interpreted as a behaviour to avoid investment in unrelated fledglings. Black Kites usually nest in loose colonies where the risk of, and selection pressures against, accidental investment in unrelated fledglings is likely to be greater than for Red Kites. Differences in aggressive chases by Black and Red Kites are better related to this than to different predation risks.

Red kite (Milvus milvus) is a European raptor. Kites of the nominal subspecies Milvus migrans migrans (hereafter called black kites) breed in the Western Palearctic and in Central Asia. Due to the extremely short period since their divergence, black and red kites can successfully hybridize. A mixed pair of black kite female and red kite male was observed during breeding seasons 2017 and 2018 in Poltva, Ukraine (i.e., in the easternmost part of red kites’ breeding territory). This pair produced three and three young in 2017 and 2018, respectively. DNA of the three young from 2018 was analyzed regarding their mitochondrial CytB haplotype and nuclear Myc gene alleles. All three young had a common black kite CytB haplotype. Myc alleles combinations suggest that the male parent could be not a pure red kite and could have a black kite among its ancestors. All three young from 2018 were presumed predated on or close to the nest by goshawk (Accipiter gentilis).

Preservation of wide-ranging top predators by site-protection: Black and red kites in Doñana National Park

-We studied the effect of growth rate, final size, hatching sequence, hatching asynchrony, and fledging asynchrony on the fledging age of Black and Red kites (Milvus migrans and M. milvus). Feather growth explained 43% and 38% of the variance in fledging age of Black and Red kites, respectively. Fledging age increased with hatching sequence and increased fledging asynchrony in relation to initial hatching asynchrony of both species, especially in broods of three chicks. Once the effect of growth was removed, no differences in fledging age related to hatching sequence were found in the Red Kite, but there was still a delay in fledging of third-hatched Black Kite chicks. Synchronous fledging of firstand second-hatched Black Kite chicks seemed to occur when both chicks had grown at a similar rate, and was caused by a delay in the fledging of the first-hatched chick. First-hatched Black Kite chicks did not delay fledging if second-hatched chicks experienced reduced growth. Differences between the two species in the third-hatched-chick fledging delay could be due to differences in nest provisioning by adults during the postfledging dependence period. Red Kites reduced provisioning to the nest as soon as the first chick fledged, while Black Kites maintained nest provisioning longer. No evidence was found supporting the idea that parents may reduce feedings to hasten first flight of their offspring. Received 20 May 1991, accepted 10 February 1992. THE LENGTH of the nestling period in birds is thought to be correlated with growth rate (Ricklefs 1968, Skutch 1976, Zach 1982b, Poole 1989). Thus, it has been used in comparative studies of growth (e.g. Bortolotti 1986a) because growth rates are more difficult to obtain. However, species with similar rates of development may have nestling periods of different length, suggesting that selective factors affecting growth rate are not the only ones acting on fledging age (Maher 1964, Skutch 1976, Zach 1982a, Freed 1988). Some studies have explored the effect of growth rates on the length of the nestling period and the extent to which growth and fledging age are related (Zach 1982a, b, Bortolotti 1984, 1986b). Hatching asynchrony within a clutch is a widespread trait in birds that may result in the development of feeding hierarchies promoting differences in growth rates (Bryant 1978, O'Connor 1984) that can influence fledging age (Clark and Wilson 1981). There also may be a parent-offspring conflict over fledging age (Trivers 1974, 1985), the chicks trying to extend the nestling period and the parents trying to force the first flight of their chicks by a reduction in feeding rates, or by means of special behavioral mechanisms (Rowan 1955, Brown and Amadon 1968, Walker 1972, Skutch 1976, O'Connor 1984, Poole 1989). A prolonged nestling period would give extra parental care (food and defense against predators) to the chicks, increasing their survival expectancy, but also could increase the rearing costs beyond the optimum for parents. Some studies on fledging of species in the Passeriformes have shown a trend for synchronizing the date of first flight among siblings, but it is not clear if fledging synchrony is obtained by a delay in first flight of the oldest chicks (Freed 1988), by an earlier fledging of the youngest (Gibb 1950, Skutch 1976, Zach 1982a), or by both phenomena (Lemel 1989). Raptors follow the general trend of interspecific increase of fledging age with body size (Newton 1979, Bortolotti 1986a). Also, the smaller males fledge at a younger age than the females in size-dimorphic species (Scharf and Balfour 1971, Sherrod 1983, Wyllie 1985, Bortolotti 1986b, Poole and Bromley 1988, Delannoy and Cruz 1988), and this has been related to differences in growth rates and final size between sexes (Newton 1979, Bortolotti 1984). Hatching sequence in the asynchronous hatching Black Kite (Milvus migrans) has been said to

I observed the natural process of family break‐up in 13 families of Black Kites Milvus migrans and five families of Red Kites M. milvus in which fledglings had been individually marked. In other broods, I performed experiments which modified the parental investment fledglings received by supplementing nests of both species with food or transferring Black Kite chicks to nests with younger or older chicks of the same species.The time of family break‐up in the Black Kite is mainly an offspring decision which is not affected by an artificial increase of parental investment. The duration of the post‐fledging period was not increased in Black Kites that were given supplementary food. Chicks transferred to nests with a younger chick did not extend the post‐fledging period, nor did chicks transferred to nests with an older chick shorten the post‐fledging period. In Red Kites, parental investment seemed to have more influence on the timing of the family break‐up. Red Kite adults invested less as parents than did Black Kites during the post‐fledging dependence period, and in nests where supplementary food was given, Red Kite fledglings stayed attached for a longer period.

Der Rotmilan (Milvus milvus) im Unteren Eichsfeld.

We characterized the spatiotemporal activities in winter grounds of the tagged Red Kites Milvus milvus originated from Austria, Czech Republic and Slovakia and wintering in south-east Europe. Birds arrived to winter grounds in Hungary, Croatia, and Greece from 10 July to 12 December (median 22 October) and departed from winter grounds between 14 February and 22 May (median 14 March), thus staying at winter grounds from 121 to 229 days (median 145, mean 161±43 SD). If we regarded kernel density estimate 80% (area of main foraging and roosting activities) as the best indicator as to the size of home range, we revealed that the size of a home range for Red Kites staying at one place through the entire winter was from 10 to 108 km2 (median 72, mean 60±36 SD) and that the size of home range for birds with local shift(s) in winter grounds was from 344 to 620 km2 (median 434, mean 466±115 SD). We found not only Red Kites at these places but often also Black Kites Milvus migrans. The numbers of Black Kites wintering together with Red Kites were higher than the number of Red Kites at all Greek winter grounds. At winter grounds in Hungary and Croatia, the number of Black Kites was lower than the number of Red Kites or Black Kites were wholly absent. Sympatric occurrences according to only direct observations of wintering Red and Black Kites were found also in some other locations in Bulgaria, Croatia, Greece and Hungary.

Avian malaria is a globally distributed vector-borne infectious disease caused by haemosporidian parasites capable of driving population declines and even species extinctions, posing major challenges for conservation biology. However, its occurrence in scavenger birds, particularly vulture species, remains poorly understood. We conducted active monitoring in northeastern and central Spain, collecting 383 blood samples from free-living birds of all age classes, including obligate (all European vultures) and facultative (red and black kites) scavenger species, to assess the occurrence of avian malaria parasites and identify their lineages using a nested-PCR protocol. Overall haemosporidian prevalence was 3.4% (13/383), with Leucocytozoon and Plasmodium detected at values of 2.3% and 1.6%, respectively. Among positive birds, Leucocytozoon spp. (69.2%) were more common than Plasmodium spp. (46.1%), including two co-infected individuals. Red kites, cinereous, bearded, and Egyptian vultures harbored both Plasmodium and Leucocytozoon, while black kites and griffon vultures only showed Plasmodium and Leucocytozoon, respectively. Black kites exhibited the highest haemosporidian prevalence (8.3%), followed by cinereous vultures (5.3%), red kites (4.8%), Egyptian (4.6%), bearded (1.9%), and griffon vultures (1.3%). Interestingly, we report 10 new host-parasite interactions and describe a novel Leucocytozoon lineage (lGYPBAR01) infecting all European vultures except the griffon vulture. We also detected Plasmodium relictum pSGS1 in an adult red kite, the first confirmed occurrence of this lineage in adults of the species. Our findings highlight a previously overlooked threat to avian scavengers and suggest that global warming may further facilitate the spread of haemosporidian-infected vectors, underscoring the urgent need for targeted conservation measures and further research into parasite dynamics in vulnerable wild populations.

Age-related variations in plasma levels of alkaline phosphatase, calcium and inorganic phosphorus in chicks of two species of raptors

Most species of migrating birds use a combination of innate vector-based orientation programs and social information to facilitate accurate navigation during their life. A number of various interspecies hybridisations have been reported in birds. The traits of parents are expressed in hybrids in typical ways which are either intermediate, combined or heterotic. Here, we analyse the different migration behaviours of medium-sized raptors, i.e., Red Kites Milvus milvus, Black Kites Milvus migrans, and their hybrids. We chose six well-established parameters to compare the behaviour of Kite hybrids with those of both parental species. When comparing 16 quantified behavioural characteristics between Red Kites and F1 hybrids and between Black Kites and F1 hybrids, significant differences were found in 10 characteristics between Red Kites and F1 hybrids but only one of the 16 characteristics between Black Kites and F1 hybrids. Hence, F1 hybrid individuals showed behaviour much more similar to Black Kites than Red Kites. It implies that the basis of the migratory behaviour of Kites is an innate program with the dominance of genetic determinants supplemented by the use of social learning from individuals of the parent species.

Previous articleNext article No AccessNotes and CommentsHatching Asynchrony: The Nest Failure Hypothesis and Brood ReductionWayne RichterWayne Richter Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 120, Number 6Dec., 1982 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/284034 Views: 9Total views on this site Citations: 14Citations are reported from Crossref Copyright 1982 The University of ChicagoPDF download Crossref reports the following articles citing this article:Felipe L.S. Shibuya, Talita V. Braga, James J. Roper The Rufous Hornero (Furnarius rufus) nest as an incubation chamber, Journal of Thermal Biology 47 (Jan 2015): 7–12.https://doi.org/10.1016/j.jtherbio.2014.10.010Corine M. Eising, Raquel Robles, Maarten Lasthuizen, Ton G. G. Groothuis Lesser double-collared sunbirds Nectarinia chalybea do not compensate for hatching asynchrony by adjusting egg mass or yolk androgens, Journal of Avian Biology 40, no.66 (Nov 2009): 635–639.https://doi.org/10.1111/j.1600-048X.2009.04556.xBONNIE J PLOGER Does brood reduction provide nestling survivors with a food bonus?, Animal Behaviour 54, no.55 (Nov 1997): 1063–1076.https://doi.org/10.1006/anbe.1997.0503Hubert Schwabl Maternal testosterone in the avian egg enhances postnatal growth, Comparative Biochemistry and Physiology Part A: Physiology 114, no.33 (Jul 1996): 271–276.https://doi.org/10.1016/0300-9629(96)00009-6Robert E. Ricklefs Sibling Competition, Hatching Asynchrony, Incubation Period, and Lifespan in Altricial Birds, (Jan 1993): 199–276.https://doi.org/10.1007/978-1-4757-9912-5_5Kevin L. Teather An experimental study of competition for food between male and female nestlings of the red-winged blackbird, Behavioral Ecology and Sociobiology 31, no.22 (Aug 1992): 81–87.https://doi.org/10.1007/BF00166340J. P. Veiga, F. Hiraldo Food habits and the survival and growth of nestlings in two sympatric kites (Milvus milvus and Milvus migrans), Ecography 13, no.11 (Feb 1990): 62–71.https://doi.org/10.1111/j.1600-0587.1990.tb00590.x Robert D. Magrath Hatching Asynchrony in Altricial Birds: Nest Failure and Adult Survival, The American Naturalist 131, no.66 (Oct 2015): 893–900.https://doi.org/10.1086/284829Hugh Drummond, Edda Gonz�lez, Jos� Luis Osorno Parent-offspring cooperation in the blue-footed boody (Sula nebouxii): social roles in infanticial brood reduction, Behavioral Ecology and Sociobiology 19, no.55 (Nov 1986): 365–372.https://doi.org/10.1007/BF00295710 Tore Slagsvold Hatching Asynchrony: Interspecific Comparisons of Altricial Birds, The American Naturalist 128, no.11 (Oct 2015): 120–125.https://doi.org/10.1086/284544 G. Thomas Bancroft The Influence of Total Nest Failures and Partial Losses on the Evolution of Asynchronous Hatching, The American Naturalist 126, no.44 (Oct 2015): 495–504.https://doi.org/10.1086/284434David J. T. Hussell Optimal Hatching Asynchrony in Birds: Comments on Richter's Critique of Clark and Wilson's Model, The American Naturalist 126, no.11 (Oct 2015): 123–128.https://doi.org/10.1086/284401Marc Bekoff, John A. Byers The Development of Behavior from Evolutionary and Ecological Perspectives in Mammals and Birds, (Jan 1985): 215–286.https://doi.org/10.1007/978-1-4615-6980-0_5Robert E. Ricklefs AVIAN POSTNATAL DEVELOPMENT, (Jan 1983): 1–83.https://doi.org/10.1016/B978-0-12-249407-9.50010-7

Second-generation anticoagulant rodenticides in the blood of obligate and facultative European avian scavengers

Molecular characterization of haemosporidian parasites from kites of the genus Milvus (Aves: Accipitridae)

MtDNA genetic diversity and population history of a dwindling raptorial bird, the red kite ( Milvus milvus)

Differences in habitat selection, diet and behaviour of resident and wintering Red KitesMilvus milvuswere studied in Donana National Park, southwest Spain. Adult resident Red Kites roosted at their nests, while immature residents and wintering birds gathered at communal roosts. Individuals remained on average for two consecutive nights (range 1–8) at the same communal roost. Wintering kites spent significantly more time foraging gregariously than residents. The use of the marsh was greater by wintering kites while residents more often used the forest. Wintering birds consumed more goose carrion than the residents. Wintering kites had larger core areas, moved farther from their roost sites to feed and changed foraging areas more frequently than residents. Among residents, adult females had the smallest home ranges (core area, distances travelled and time spent flying). We suggest that Red Kites wintering in Donana occupy the marsh because it provides high food availability, and is vacated by Black KitesM. migranswhich exploit this profitable habitat during the breeding season.