The fungal succession on hawk pellets

[ 81 ] Trans. Brit. mycol. Soc. 46 (I), 81-90 (1963)'

THE FUNGAL SUCCESSION ON HAWK PELLETS By ROY WATLING

Royal Botanic Garden, Edinburgh Pellets of Falco tinnunculus collected from a nesting site were kept in damp chambers. The fungi which appeared on them were identified and described and the date of the first appearance of sporophores noted. A possible succession was drawn up and is suggested. The survey was supplemented by material from a second nesting site and from pellets collected in the field. Fifty-two fungi and one alga were obtained from the pellets and from a bird corpse found in contact with the pellets.

In the literature there are many accounts of the succession of fungi on coprophilous substrates and of the part played by fungi in the decay of herbaceous plant debris in and on the soil (Chesters, 1948), of woody substrates such as trunks and stumps (Mangenot, 1952), and more recently of the successive colonization from senescence onwards of specific plants by fungal forms (Webster, 1956; Webster & Hudson, 1958). Little, if anything, has been described on the colonization and breakdown of animal matter, other than faeces, in the field. Perhaps the only suggestions come from a project by Crossland & Needham (1904) who studied the colonization of a cast-out hearth rug in a wood, and more recently from a study by Griffin (1960) who examined the colonization of sterile hair in contact with the soil. However, many isolated records are available of uncommon, unique and interesting fungi from animal debris, e.g. sheep horns (Onygena), owl pellets (Anixiopsis), a rabbit corpse (Lachnea), etc. As the records are many and varied, it was felt that the examination of hawk or owl pellets would yield interesting results, especially as in comparatively recent times techniques for isolating dermatophyte-like fungi from soil have been shown to be applicable throughout the world. The study was carried out over 13 weeks during 1959 (June~October). PROCEDURE

Active nesting sites of the common kestrel were located in a quarry at Hathersage and at Ridgewalk Moor, both in Derbyshire. Seven pellets and a bird corpse from Hathersage were examined in detail, the findings being supplemented by the less extensive examination of undatable pellets from the same region and from a much older kestrel site at Ridgewalk Moor where animal debris was stratified about the nesting ledge and a whole system of decaying pellets was available for study. At Hathersage plant debris, animal waste and old pellets immediately about the nest were cleared away, so that freshly regurgitated pellets could be collected. The nest was visited once every 2 or 3 days. The pellets fell on to the ledges immediately about the nest and on to a grassy raised part of the quarry 6

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floor, or could be collected in and under a patch of Pteridium at the base of the quarry face. Each pellet on collection was placed in a sterile screw-capped phial and in the laboratory the pellet was mounted in a jam-jar fitted with a glass lid on a filter-paper above a pad of moist paper pulp. The whole system was sterilized before use. After mounting, the pellets were examined every 3 days with a binocular microscope. The temperature of the laboratory in which the jars were kept varied normally between 19 and 21° C. and only one side of the chamber faced the light. Table

I.

Hathersage-site pellets. List of species and number of days in damp chamber before the appearance of the fungus as a distinct colony Pellet samples

W6 Acremoniella atra (Corda) Sacco Aleurisma cr. keratinophilum Frey 17 Aleurisma sp. 2 Aleurisma sp. 3 Aleurisma sp. 4 Aleurisma sp. 6 cr. conidial Arthroderma quadrifidum Dawson & Gentles (= Trichophyton terrestre Durie & Frey) Anixiopsisstercorarea (Hansen) Hansen 18 Arthrobotrys oligospora Fres. Chaetomium globosum Kunze Cladosporium herbarum (Pers.) Link Fusarium sp. 1 F. sporotrichoides Sherb. Fusarium sp. 3 Fusarium cf. concolor Reinking ? Humicola sp. Melanospora sp. cr. zamiae Corda Monodictys levis (Wilts.) Hughes Mucor circinelloides Van Teigh. 6 M. hiemalis Wehmer 3 M. javanicus Wehmer M. plumbeus Bon. M. ? racemosus Fres. M. spinescens Lendner Mucor sp. I near rouxianus (Calmette) 3 Wehmer Mucor subtillissimus Oudemans Oospora sulphurea (Preuss) Sacco & VogI. Penicillium cr. cyclopium series Stachybotrys chartarum (Corda) Hughes Trichocladium asperum Harz Trichoderma viride (Tode ex Fr.) Harz Trichothecium roseum Link

10

12

23 9

8

16 30 16 24

16

16 33 II

39 44

16

16

16

5

2

2

II II

5

5

53

23

30

24 10

39 2

6

The date of appearance of fruit-bodies was noted and a suitable colony of the fungus selected for culture. The fungus was always described from the colonies on the pellet. The notes obtained were supplemented, often in greater detail, whenever possible from pure cultures of the fungus. Depending upon the species isolated, different freshly prepared media were employed in their culture, according to standard practice.

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Not all the species produced fructifications on the pellets, but by carrying out suspension techniques generally applied to soil fungi other species, often of different genera, were isolated from fragments of hair and bone in the pellets. The distribution of these fungi on and within the substratum appears to be partially dependent on the fauna of the pellet. Thus nematodes were observed to be encrusted with spores of Aleurisma sp. I in some pellet samples. These transported the spores to areas beneath the surface and no doubt brought others, perhaps of different species and genera buried in the inner parts, to the surface. The pellets were studied throughout their decomposition or until the mite population became uncontrollable. Table

2.

Ridgewalk Moor pellets. Fungi appearing during an incubation period in damp chamber Pellet fragments JX

Absidia orchidis (Vuill.) Hagem. Acrostalagmus albus Preuss Alternaria tenuis Nees Arthrobotrys oligospora Fres. Chaetomium globosum Kunze Cunninghamella echinulate Thaxter Fusidium ? griseum Grove Geomyces vulgaris Traaen Geotrichum. candidum Link C£ Lachneacadaverina Velen. Melanospora cf. zamiae Corda Monodictys levis (Wilts.) Hughes Mortierella jenkinii (Smith) Naumov Mucor hiemalis Wehrner M. ? janssenii Lendner Mucor cf. oblongisporus Naumov O>rygena corvina (A. & S.) Fr. Penicillium steckii Zaleski Stachybotrys chartarum (Corda) Hughes" Stemphylium sp. Trichocladium asperum Harz Trichoderma viride (Tode ex Fr.) Harz

Pellets up to I month

Pellets up to 6 months

,---~

,----~

JI

J2

J3

J5

J7

Pellets old-up to I yr. J4

Pellets older than I yr . J6

x

x

x x x x x x x x

x x x x

x x x x x

x

x x x x

x x

x

x

x

In the different samples from Hathersage the number of days elapsing before fructification of one fungus species was more or less of the same magnitude, when the position of the pellet about the nest was taken into consideration. Discrepancies between the results for different positions were due to differences in the micro-climate and to the total composition of the pellet (Table 3). Dissection demonstrated that the pellets were an intermixed collection of animal, or more rarely vegetable material, the composition depending almost certainly on the availability and type of prey of the kestrel. This constitution appeared to be altered by weather conditions and the time of the day when the bird hunted. Thus, no two pellets were identical, and all were heterogeneous. Each pellet at Hathersage had a slightly modified form of the same succession of fungi (Table I) and this appeared to be repeated with some of 6-2

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the species and a few additional forms at the Ridgewalk site (Table 2) where kestrels had used the site for over two breeding seasons. Many isolates from Hathersage were undoubtedly wind-borne contaminants, e.g. Cladosporium, Alternaria, Penicillium, etc., as was indicated by air spora analysis at the nesting site. Others, especially the mucoraceous element, may well have originated from the soil on which the pellets were lying. This was a comparatively recent soil composed of fragments from the quarry and plant debris. Saprophytic fungi were demonstrated to be present in large numbers in this soil. There is little doubt that if the pellets had been allowed to rest longer on the soil other such fungi would have appeared in the succession as facultative colonists. Table 3. Time ofappearance of Mucor hiemalis on Hathersage pellet samples after incubation in damp chamber, compared with the position ofthe pellet about the nesting site No. of days

,

,

\

Sample On soil amongst Pteridium at base of cliff Grassy platform in quarry Bare nesting ledges Nesting ledge with soil Bird corpse and remains on nesting ledge with sparse T eucrium, Agrostis etc.

1

Sample

16 3 16 5

16

2

2

2

Sample 3

2

3

IDENTIFICATION OF SOME NOTEWORTHY ISOLATES

Aleurisma spp. and Geomyces sp.-Sporotrichum s, lato A whole series of white hyphomycetes was isolated from pellets from both the Derbyshire sites. At least five different types were examined but none was successfully cultured for long periods of time on the media employed, though both synthetic and natural media were used, including pellet decoction and dung extracts. All but one could be assigned to the little-known genus Aleurisma, conidial production being exactly as featured and described for A. carnis (Brooks & Hansford) Bisby. The spores, in contrast to those borne on sterigmata as in Sporotrichum s. stricto, are aleuriospores and, owing to their method offormation, were variable, even within the isolate, in size and shape. These conidia are ovoid or ellipsoid, slightly truncate at one end, flatly pear-shaped or almost spherical. In the additional single isolate they were more consistent in shape and not true aleuriospores. This isolate will be discussed further below. In all five isolates the aerial conidiophores arose from the vegetative mycelium and bore short branches which were often in groups of two or three. These laterals again branched, each branch being cut off from the parent hypha by a septum. The branches segmented further and produced the conidia terminally and singly. They are really terminal chlamydospores. All the collections are characterized by the early disappearance of the hyphae, leaving just a mass of spores and the short cells of the lateral branches. Only recently has at least one of these collections been named specifically and it agrees in most respects with A. keratinophilum. Another collection,

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Aleurisma sp. 6, appears to be very similar to conidial Arthroderma quadrifidum ( = Trichophyton terrestre) in consistently producing racquet hyphae and microspores of a similar size. However, ifit is this species then it is a strain which lacks macroconidia. The other three isolates have not been named specifically. G. Smith has confirmed the formation of aleuriospores in A. keratinophilum and A. sp. 2. and agrees with this generic placing. I am grateful to J. Elphick for suggesting an epithet for Sporotrichum s. lato sp. 5, differing from the other isolates in having typical sterigmata. In a recent communication J. C. Gentles informs me that he has isolated similar fungi by hair-bait techniques from soil. These were strains with small and large conidia, respectively, both referable to Aleurisma. A. keratinophilum Appeared on pellet sample WI collected from grassy platform. Colonies, tufted, grouped, never bigger than 0'75 mm. diam., white, subgelatinous then dry, vegetative hyphae creeping, septate, branched. Conidiophores ± erect up to 60fA- long, 3fA- wide, repeatedly branched with up to four branches, each branch segmenting into short cylindrical cells 3-5fA- long. Conidia hyaline terminal, borne on both lateral and main branches, which often develop inflations as the conidia form. Conidia smooth, dry, r-celled, 8'5-12 x 5'5-7 fA-, obovoid with slightly thickened wall, truncate base, often as if with a basal frill,

Aleurisma sp.

2

Appeared on pellet sample W 3 collected amongst Pteridium fronds. Colonies orbicular, 0'5-1'5 mm. diam. Vegetative hyphae branched, hyaline, septate, I-3 fA- wide forming a sparse turf. Conidiophores short, IO-15fA- long, with numerous side-branches. Laterals branching further, but unequally. Conidia terminal, smooth, fairly thin-walled, hyaline, I-celled, obovoid-ovoid, truncate at one end, 4-5 x 2'SfA-. Conidiophores I' 5-2 fA- wide, branches usually 8 fA- long, but often shorter and unequal.

Aleurisma sp. 3 Appeared on pellet sample W 7 collected from the ledge about the nesting site. Vegetative hyphae hyaline, 4-5fA- wide, occasionally up to 6fA-, obscurely septate, interwoven and greatly branched. Outer wall of all branches granular, rarely if at all smooth. Conidiophores roughened as the vegetative hyphae, bearing minutely but distinctly granulate terminal hyaline conidia 5'0-5'5 x 7·5-8·5fl-. Aleurisma sp. 4 Appeared on surface of pellet sample W 7' Vegetative hyphae creeping, septate, hyaline, as in Aleurisma sp. 2, with which it may be considered under a single epithet. Conidia truncate, hyaline, single-celled, 4'0-5'5 x 2·5-3'°fA-·

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Aleurisma sp. 6 cf. conidial Arthroderma quadrifidum ( = Trichophyton terrestre) Appeared on colonies developed on pellet sample W 7 collected from nesting ledge. Vegetative hyphae as a thin film over fur debris, with inflations at the septa, hyaline, 2,8-3'5jL wide; inflations smooth, containing no oil globules or granules, 9- lOX 12-6 jL. Distance between each inflation is variable though ca. 35jL. Conidiophores hyaline, branched, lateral branches being quite short, 2·8jL wide. Conidia I-celled, hyaline, truncate and with rounded apex, smooth 7'0-8'0 x 3-4·5jL. A similar isolate from a hawk pellet collected at Hull was determined as A. carnis. It produced, on the surface of the pellet, innumerable white, pinkish or yellowish woolly patches, just as Brooks & Hansford (1923) described from cold storage meat. Critical examination of this isolate confirms that the other aleurismoid hyphomycetes on pellets from Derbyshire should be placed in the form genus Aleurisma.

Geomyces vulgaris From material growing on pellet sample] 2 soon after placing in the damp chamber. White colonies composed of septate, hyaline vegetative hyphae creeping over the substrate, 2'0-3'ojL wide. Irregularly branched laterals 1'5-2'OjL in width, Conidiophores 4"0-8'5jL long, simply or complexly branched many times, Laterals which may number up to 6-8, 1'5-3'OjL wide, Conidia slightly verrucose, hyaline, 4-5 x 3'5jL, borne sometimes almost sessile on main branch, more usually terminally on slightly tapering branches as in Vuillemin's conception of Sporotrichum. Lachnea cadaverina Appeared on pellets from Ridgewalk Moor after 7 days in a damp chamber. Under the binocular microscope appeared pale salmon pink, becoming tinted yellowish or pale brownish, especially when drying. The apothecia are produced from a distinct white basal mycelium which spreads over the filter-paper about the pellet. Apothecia up to I mm. diam., usually smaller, 0'25-0'75 mm., gregarious, single or crowded. At first growing at edge of filter-paper but rapidly colonizing central regions about pellet debris. Hyphae probably colonizing the filter-paper due to competition on the surface of the pellet itself. Appears first as a solid frustrum, becoming saucer-shaped, sessile but distinctly tapering slightly towards the base, Asci long, cylindrical, apex rounded, operculate, 8-spored obliquely arranged uniseriate, 135-140 x 10-11 jL. Spores smooth-walled, hyaline, ellipsoid with rounded ends, r-celled, 13'0-14'5(15'5) x 6'5-8'OjL. Paraphyses elongate, slender, septate, slightly clavate, 145 x 3·SjL. Vegetative hyphae 4'5-8'ojL in width, septate, hyaline, branched. Hyphal extensions on the margin of apothecia clavate, 13'O-14"OjL wide at apex, giving the edge a ragged appearance. Associated with pointed, r-septate thick-walled hairs, with a distinct basal swelling below the septum. Freeze microtome sections of the apothecia showed a rudimentary stipe composed of angular cells.

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Described originally (? and only) from the hair of a dead rabbit in Czechoslovakia, this collection differs only in being a little smaller and of a slightly different colour. W. D. Graddon to whom it was sent suggests it to be a Cheilymenia and it is to him I am indebted for drawing my attention to this Central European collection. Material deposited as Watling Herb. no. 37.

Acrostalagmus sp. A fungus resembling A. albus Preuss formed extensive colonies on a single pellet collected from under Pteridium (sample W s). It was also collected several times on pellet samples from Ridgewalk Moor. Vegetative hyphae white then greyish white, creeping, septate 1'5-2 fL wide, bearing erect long slender conidiophores. These are up to IOofL long, I'5-2'OfL wide, bearing at intervals 3-4 whorls of phialides 16-18fL long. The lateral branches also bear similar whorls of phialides, the distance between corresponding whorls being of the magnitude 25fL. Phialides I'5fL wide tapering to the conidium, smooth. Conidia smooth, elongate with rounded ends, small, 4'2-5'6 x I·5-2fL. True phialospores borne in mucilage. Many species of Verticillium have been described in the literature but many, especially the saprophytic ones, are lacking complete diagnoses. The fungus described by Preuss closely resembles, but for the smaller spores, the above collection. CONCLUSIONS

The results suggest a picture of the succession of fungi on kestrel pellets from the time of their ejection until their ultimate decomposition. Thus, for all the pellets five distinct stages could be recognized by the appearance of a certain fungus or group of fungi: I. Mucor hiemalis stage. The majority of the phycomycetous element appeared during this time, though some of the species sometimes continued into later stages, but then only spasmodically. 2. Aleurisma-Sporotrichum stage, characterized by members of the latter genus (5. lato), but also by the appearance of many dematiaceous hyphomycetes, e.g. Stachybotrys and Trichocladium, and the loss ofthe phycomycetes. 3. Anixiopsis stage, characterized by A. stercorarea, accompanied by the extensive growth of the hyphomycetous element associated with stage 2 and the appearance of additional ones, occasionally accompanied by their perfect states. Disappearance of the Aleurisma complex. 4. Final stage when most of the available nutrient had been removed, except for the more resistant parts ofbeetle elytra and fur; characterized by Onygena corvina, as suggested by material from the Ridgewalk Moor site. Other fungi gradually die out and are replaced by an algal scum consisting in the main of Pleurococcus naegelii Chod. Arachniotus ruber (Van Teigh.) Schroet. appeared on hawk pellets collected in the field at Hull, Yorks, at a similar stage of decomposition as those bearing O. corvina. 5. Superimposed on this 4-stage system is one typified by the appearance of Arthrobotrys oligospora, which developed its characteristic nematode trapping systems and usually began to fruit before stage 3, accompanied by a

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depletion in the nematode population. General observations suggest that the time of conidiophore production is dependent on the nematode induction period and population number inhabiting the pellet.

Notes on the occurrence ofsome of the fungi recorded Anixiopsis stercoraria (Watl. Herb. no. 47) appears to have been recorded only twice previously from this country, once from owl pellets (Massee & Salmon, 1902) and more recently from soil (Booth in litt.). Onygena corvina (Watl. Herb. no. 38) is widely distributed but always on fur or hair substrata. Rostrup believed Sporotrichum lanatum Wallr., recorded from the same substratum, to be its conidial state. This was unconfirmed during the study of pellets from Derbyshire. Arachniotus ruber has been recorded from dung several times, but not apparently in recent years (Massee & Salmon, 1902). Specimens have been deposited at C.M.I. as IMI 77673, and Watl. Herb. no. 48. The Aleurisma spp. recorded appear to be closely related morphologically to those fungi which are agents of ringworm in mammals. These observations indicate that hawk pellets are a natural habitat of these keratinophilic fungi and fungi related to them. Stachybotrys chartarum, Chaetomium globosum and T richocladium asperum have all been recorded from rotting paper in contact with soil and are also a typical part of the coprophilous succession. Monodictys levis has been isolated from soil from a number of localities about Sheffield, e.g. Fulwood, Hathersage, Ecclesall. The rest of the hyphomycetous element is composed, on the whole, of common members of a succession on rotting organic material on or in the soil (Gilman, 1957). Most are soil organisms and have no doubt colonized by spread from the soil, but some, such as Alternaria tenuis and Cladosporium herbarium, may have colonized by dry spores from the air, and the Fusarium spp. (e.g. F. sporotrichoides) by rain splash. Many of these hyphomycetes have been recorded from the facultative part of the coprophilous succession. The pellets from the ledges (W4 , W 6 , W 7, and W s) contained fewer colonists than those in direct contact with the soil on the quarry floor (WI and W s) or those under the Pteridium, amongst herbaceous debris (W 2 and W 3 ) . They all, however, gave the same picture of colonization. DISCUSSION

There are no papers as far as the writer is aware of a natural succession of fungi to be found on a similar or identical substratum. Crossland & Needham (19°4) noted carefully the date of appearance of species which colonized an old cast-out hearth-rug in Pecket Wood, Hebden Bridge, Yorkshire. It is to their list offungi that the succession on pellets has some resemblance. The species they listed include typical keratinolytic and cellulolytic colonists. The hearth-rug was composed of both animal and plant fibres and so additional fungi known to colonize plant debris were also recorded by them. They did not tabulate many microscopic fungi and so only a rough comparison can be made. However, Griffin (1960) has

Fungi of hawk pellets. R. Watling studied the colonization of hair bait in soil and there are many similarities with his list of fungi. Griffin found the first colonists to be fungi with a high competitive saprophytic ability, rapidly utilizing th e less complex nutrients of the substrate; these included various members of the Mucorales, Fusarium spp. and certain Penicillium spp. H e recognized two further stages: a group including many cellulolytic fungi, such as Humicola spp . and Chaetomium spp. , and a final stage characterized by keratinolytic fungi, particularly Keratinomyces ajelloi Vanbreuseghem and Microsporum gypseum (Bodin) Guiart & Grigoraki. Pellets were once again collected from the Derbyshire site during the early summer of last year (196 I ) . The same series of fungi was isolated and the succession confirmed. It is hoped to extend this study further, to pellets of other birds of prey. Thanks are due to Dr]. Webster under whose supervision this study was carried out as an undergraduate problem for the partial fulfilment ofB.Sc. with Hons., Botany Department, Sheffield University ; also to Dr C. Booth, ]. Elphick, Commonwealth Mycological Institute, G. Smith, London School of Hygiene and Tropical Medicine, and W. D. Graddon who have brought descriptions to my notice and helped in the identification of critical forms. I am also grateful to Dr W. Blyth, Department of Botany, Edinburgh University, who has encouraged the production of this notice and kindly read through the typ escript and to Dr C.]. P. La Touche, Leeds Infirmary for sending me cultures of dermatophytes for comparison. REFERENCES AJELLO, L. (1959) . New Microsporum and its occurrence in soil and on an imals. Mycologia, 51, 69-77· BENJAMIN, R. K. ( 1956) . New genus of Gymnoascaceae with review of other genera. El Al iso, 3, 301-328. BISBY, G . R. (1944) . Notes on British H yphomycetes. Trans. Brit . mycol. Soc. 27,101-112 . BROOKS, F. T. & HANSFORD, C. G . ( 1923). Mould growths upon cold store meat. Trans. Bri t. mycol. Soc. 8, 113-1 41. CHESTERS, C. G . C. (1948) . Contribution to the study of soil fun gi in the soil. Trans. Br it. mycol. Soc. 30, 106- I 17. CROSSLAND, C. & NEEDHAM,]. (1904) . Fungus flora of a cast out hearth rug. Naturalist, Lond., 19 0 4, 359-363. DAWSON, C. O. & GENTLES,]. C. (196 1). Perfect states of K eratinomyces ajelloi Vanbreuseghem, Trichophyton terrestre Durie & Frey and Microsporum nanum Fuentes. Sabouraudia, 1,49-57. DURIE, E. B. & FREY, D. ( 1957). New species of Trichophyton from New South Wales. Mycologia, 49, 401-41 I. FREY, D. (1960). Isolation ofa new species of Aleurisma from soil in Australia and New Guinea. Mycologia, 51, 641-646. FRIES, E. ( 1829) ' Systema Mycologicum, III. Upsala. GILMAN, ] . C. ( 1957). A manual of soil f ungi, znd ed ition. Iowa . GRIFFIN, D . M. (1960). Fungal colonization of sterile hair in contact with soil. Trans. Br it. my col. Soc. 43, 583-596. K UEHN, H. H . (1957). Observations on Gymnoascaceae. IV. Mvcologia, 49, 55-67. K UEHN, H. H. (1957) . Observations on Gymnoascaceae. V. Mycologia, 49, 694-705. K UEHN, H. H . (1958) . Preliminary survey of the Gymnoascaceae. Mycologia, 50, 4 17-439.

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LIND, J. (19 I3). Danishfungi as represented in the herbarium if E. Rostrup, Copenhagen. MANGENOT, R. (1952). Recherches methodiques sur les champignons de certain bois en decomposition. Rev. gen. Bot. 59, 38 1-399, 439-47 1, 477-5 19, 544-555. MASSEE, G. & SALMON, E. (1902). Coprophilus fungi. II. Ann. Bot., Lond., 16, 57-93. TRAAEN, A. E. (1915). Untersuchungen uber Bodenpilze aus Norwegen. Nyu Mag. Natura. 52, 19-121. WEBSTER, J. (1956). Succession of fungi on decaying cocksfoot culms. Part I. ]. Ecol. 44, 5 I 7-544· WEBSTER, J. (1957). Succession of fungi on decaying cocksfoot culms. Part II. ]. Ecol. 45, 1-30 • WEBSTER, J. & HUDSON, H. J. (1958). Succession of fungi on decaying stems of Agropyron. Trans. Brit. mycol. Soc. 41, 165-177.

(Accepted for publication 13 May 1962)