Volume 5 1994 No.1 ORNITOLOGIA NEOTROPICAL 5: 1- -55.1994 @ The Neotropical Ornithological Socie NESTING, BEHAVIOR, OISTRIBUTION, ANO SPECIATION OF PATAGONIAN ANO ANOEAN GROUNO TVRANTS (MYIOTHERETES, XOLMIS, NEOXOLMIS, AGRIORNIS, ANO MUSCISAXICOLA ) Fran9ois Vuilleumier Depar!men! of Ornithology, American Museum of Natural History, Central Park West a! 79!h Street New York, NY 10024, U.S.A. Resumen. La biolog¡a, distribuci6n y evoluci6n de los tiránidos de monte o terrestres {Tyrannidae, subfamilia Fluvi- colinae) es todav¡a poco conocida. Nidos de cuatro especiespatag6nicas {Xolmis pyrope, Neoxolmisrubetra, Neoxol- mis rufiventris, y Muscisaxicola capistrata) fueron estudiados durante expediciones a la Patagonia en 1988 y 1992 y nidos de dos especies altoandinas {Myiotheretes rufipennis y Agriornis andicola) fueron observados durante una expedici6n al Perú en 1975. Los nidos de Neoxolmis rubetra y de Agriornis andicola son aparentemente los primeros señalados para estas dos especies, y aquellos de Neoxolmis rufiventris y Myiotheretes rufipennis los segundos para estasespecies. Los nidos de Xolmis pyrope y Muscisaxicola capistrata demuestran la nidificaci6n de la primera especie en matorral patag6nico fuera del bosque de Nothofagus {Fagaceae),y confirman la nidificaci6n de la segunda en el norte de la Patagonia. Estos datos sobre nidificaci6n son ampliados con observaciones de terreno sobre la con- ducta, los bi6topos, la abundancia relativa y la distribuci6n geográfica de estas seis especies. Además, se analiza de manera comparativa aspectos del comportamiento, de la biogeograña y de la evoluci6n presentados por tiráni- dos terrestres en los géneros Myiotheretes, Xolmis, Neoxolmis, Muscisaxicola, y Agriornis. Se discute especialmente patrones de simpatr¡a, alopatr¡a, y parapatr¡a, y de aislamiento reproductivo. La especiaci6n en este grupo de tiráni- dos se analiza en términos de tres modos de especiaci6n: peripátrico, dichopátrico, y parapátrico. Los fluvicolinos son muy bien representados en varios biot6pos de puna y estepa andino-patag6nicos, donde constituyen un alto porcentaje de esasfaunas, y donde presentan fen6menos de radiaci6n adaptiva. Por esas razones, estos tiránidos merecen amplio análisis, para facilitar el cual se sugieren muchas cuestiones para estudios futuros. Abstract. The biology, distribution, and evolution of the bush and ground tyrants {Tyrannidae, subfamily Fluvico- linae) remains poorly known. Nests of four Patagonian species {Xolmis pyrope, Neoxolmis rubetra, Neoxolmis rufi- ventris, and Muscisaxicola capistrata) were studied during expeditions to Patagonia in 1988 and 1992 and nests of two high Andean species {Myiotheretes rufipennis and Agriornis andicola) were observed during an expedition to Perú in 1975. Apparently these are the first reported nests of Neoxolmis rubetra and of Agriornis andicola, and only the second of Myiotheretes rufipennis and of Neoxolmis rufiventris. The nesting records of Xolmis pyrope and Muscisaxicola capistrata show that the first species lives in Patagonian matorral away from Nothofagus {Fagaceae) forest, and confirm that the second breeds in northern Patagonia. Besides data on nesting, detailed field observa- tions on behavior, habitat preferences, relative abundance and geographic distribution of these six species are also given. Comparative aspects of the behavior, biogeography, and speciation of bush and ground tyrants of the genera Myiotheretes, Xolmis, Neoxolmis, Agriornis, and Muscisaxicola are reviewed. Particular attention is paid to patterns of sympatry, parapatry, allopatry, and reproductive isolation, in order to describe and analyze the occurrence of three modes of speciation: peripatric, dichopatric, and parapatric. Fluvicoline flycatchers constitute an important component of Patagonian steppe and high Andean puna habitats, where they make up a high percentage of these faunas and where they show adaptive radiation. For these reasons, these flycatchers deserve further study. To facili- tate future work a number of general as well as specific questions are presented. Accepted 11 July 1993. Key words: Myiotheretes, Xolmis, Neoxolmis, Agriornis, Muscisaxicola, Tyrannidae, Patagonia, Andes, nesting, be- havior. distribution, speciation. VUILLEUMIER INTRODUCTION Perú (18 October -9 December 1975), and of Bolivia (8 October 1967- 30 January 1968), as Among the bush and. ground tyrants discussed part of a research program on the origins of high by Smith & Vuilleumier (1971), the genera Andean birds (Vuilleumier & Simberloff 1980, Myiotheretes, Xolmis, Neoxolmis, Agriornis, and Vuilleumier 1986, 1994), I found nests of, and Muscisaxicola collectively show impressive radia- made other observations on, six species of bush tions, components of which include parallel pat- and ground tyrants (Myiotheretes rufiPennis, Xol- terns of sympatry, parapatry, and allopatry in the mis pyrope, Neoxolmis rubetra, Neoxolmis rufiven- high Andes and in Patagonia (Vuilleumier 1971: tris, Agriornis andicola, and Muscisaxicola capi- 203-230), and congruent speciation patterns in strata), for which biological and distributional the arid diagonal of Brazil and Argentina information is scanty aohnson 1967: 234, (Fitzpatrick 1980: 1277-1278). These five genera 251-252, 264-266; Humphrey et al. 1970: (listed above according to the sequence and 268-270,271-272; Veríegas& Jory 1979: 157- nomenclature of Traylor 1979) belong to what 158,159-160; Clark 1986: 230,234,236; Fjeldsa Traylor (1977: 159-166; 1979: 112-186) dia- & Krabbe 1990: 502-504, 509-510). gnosed as the subfamily Fluvicolinae, and to For each of these six species, after a review of its systematic position, I describe these nesting xicolawhat LanyonGroup." (1986: 42-52). called the "Muscisa- observations and report data on behavior, rela- Unfortunately, lack of comparative infor- tive abundance, habitat preferences, and geo- mation on many species in the monophyletic graphic distribution. I then discuss comparative assemblage of 31 species in five genera (sensu aspects of the behavior and biogeography of all Traylor 1979) that make Up the main part of bush and ground tyrants in the genera Myiothere- Lanyon's Muscisaxicola Group (including even tes, Xolmis, Neoxolmis, Agriornis, and Muscisaxi. basic data on breeding biology, behavior, habitat cola; analyze their patterns of sympatry, parapa- try, and allopatry; and, finally, review speciation preferences,and geographic distribution) impedes patterns in terms of various modes of species a clear understanding of their phylogenetic formation and of reproductive isolating mecha- relationships and, consequently, of their evolu- rnsms. tion. To help remedy some of these deficiencies, Localities mentioned in this paper are shown I report herein new field information, review in Figures 1 (southern South America), 2 (Fuego- and synthesize old and recent evidence, and offer Patagonia), 3 (parts of the Andes of Perú), and 4 speculations designed to fill gaps and to stimulate (Bolivia). The spelling of collecting localities and further research. Because Tyrannidae in general, other geographic names in Figs. 1-4 follows the and bush and ground tyrants of the subfamily ornithological gazetteers for Perú (Stephens & Fluvicolinae in particular, are í>ften, together Traylor 1983), Bolivia (Paynter 1992), Chile with Furnariidae and Emberizidie, numerically (Paynter 1988), and Argentina (Paynter 1985). In and ecologically dominant among the passerine a few instances, however, I have followed what component of high Andean ahd Patagonian seems to be current or local usage.For exaínple, avifaunas (Vuilleumier 1986: 591-592, 1993, the well known collecting locality "Huanuluan" 1994), intensive study of their evolutionary in Río Negro, Argentina (e.g., Peters 1923: 276, relationships should figure prominently in ana- Wetmore 1926b: 402) is spelled "HUANU- lyses of Andean-Patagonian biogeography. LUAN" by Paynter (1985: 131). The present During expeditions to Patagonia (5 February owner of this ranch, Mr. J. A. Chuburu, spells it ~ 3 April 1965, 1 November- 13 December "Huanuluán" and I have retained this spelling in 1985,7 February -4 March 1987, 1- 30 Octo- Figure 1. ber 1987,15 -22 January 1988,2 -30 Novem- ber 1988,5 -18 November 1991, and 18 Octo- ber- 15 November 1992) as part ofa research SPECIES ACCOUNTS program on speciation and evolution in Patago- The order, sequence, and nomenclature of nian birds (Vuilleumier 1985, 1991a, 1991b, 1993), species in this section follow the classification and during expeditions tothe Andes of northern proposed by Traylor (1979) in Peters' check-list. :2 PATAGONIAN AND ANDEAN GROUND TYRANTS ,;; o Y;"m"" i :~,; I ARGENTINA ; ""iÓ"\', O ,,: 4 I '\ La Pampa ".'I"r~ 38° c, \P"","" BuenosAires I,," LI~!ii... ,,;:.-, M,"",d, B.hi.Bl.",. "'~( , "'- .do ~;~':'¡fl"' J,,~ , ,~.;,, ,., " ~ c ~ V'¡d, ~~. , ~o 40° ", ", ," ., .! V,¡,he,. -fe,i';/~~;;:;O:"nc",á " d,P.,..""" ",,';oMoo\\ 42° p,m",""v,¡d" (>W'"dChiloéJ ~1,~ ~i;1:')!!;',~"11. ",",~í?;)t:~',t. "e""' ';~,," .;:.' "".~ ~" cf~ 44° i;)~ q~,g., f\Chubut :,~?i~~~~~ ::!\ -C,moro"" ";"\A¡:;.ñi~."~ ,~ ,"""'M=,""",C"","..,I C,bod",B,h¡" .cP~i;{~;! ...~ ;~Z,~; :.:;;, ComodoroRi"d,,¡, 46° Atlantic ~ ~ ,f ?e' ,; ~ 7.4, .Puorto~d. I)e,.odo Ocean {,;,;;;(, ,~~:- SantaCruz E.'oc;, El C"odro 48° ó,~, , ~~ '"JW¡án RIo-C~, Pu,rt"S~I"Cru, 50° , c ~; 0' w O VI'8'"" 52° ~~ "0"""' ~pFalkland Islands ("las MaMn") 0 G,m.. Brumwi,k Po"imlli. ~ 54° Pa C iii c (, >1000~..~ ,;:::/.;;;;:.0 Ocean km , , , , , , , 50 100 150 200 250 300