COSTS AND BENEFITS AMONG PARTICIPANTS IN MIXED. SPECIES FORAGING FLOCKS IN LOWLAND DECIDUOUS FORESTS, HUAI KHA KHAENG WILDLIFE SANCTUARY

WICHYANAN LIMPARUNGPATTHANAKIJ

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE (ENVIRONMENTAL BIOLOGY) FACULTY OF GRADUATE STUDIES MAHIDOL UNIVERSITY 2014

COP}'RIGHT OF MAHIDOL UNIVERSITY Fac. ofGrad. Studies, Mahidol Univ. Thesis / iv

COSTS AND BENEFITS AMONG PARTICIPANTS IN MIXED.SPECIESI FORAGING BIRD FLOCKS IN LOWLAND DECIDUOUS FORERESTS, HUAI KHA KHAENC WILDLIFE SANCTUARY

WICHYANAN LIMPARLINGPATTHANAKIJ 5337750 SCEB/M

M.Sc. (ENVIRONMENTAL BIOLOCY)

TLIESIS ADVISORY COMMITTEE: JENJIT KHUDAMRONGSA' GEORGE ANDREW GALE. Ph.D,

ABSTRACT This study focused on mixed-species flocks of birbirds in a lowland deciduous forest a habitat type threatened heavily in the regioegion, p marily from logging and clearance for agriculture, and which is understudied)d irin comparison with evergreell forests. Data on the composition and structure of a totaltor of 657 mixed- species foraging bird flocks were collected fi:om January to Decemcember, 2012 in Huai Kha Khaeng Wiidlife Sanctuary, . The flocks could be dividlivided into two types: those composed of small-sized and those composed of mediurrdium-sized birds. The species most prevalent in flocks included gregarious "leader"er" species, such as laughingtluLrshes (Garrulax spp.), the conspicuous anti-predaredator alalm-calling ''serltinel" species such as drongos (.Dictulus spp.). and the BlacBlack-naped Monarch (Hypothymis dzwea). Most species showed a lower mixed-flocking.ing propensity during the breeding seasot. Several species in medium-sized bird flocksrks showeds significant behavioral adiustments in which they foraged closer to the groundnd irin mixed flocks led by (ground-feeding) laughingthrushes. Four species of woo<,oodpeckers showed significantly iower vigilance rates when participating in mixed-spel-species flocks. Their vigilance rates were also negatively conelated with flock size. "SentSentinel" species sLlch xs the Greater Racket-tailed Drongo (D poradiseus). Ctow-biw-billed Drongo (D. utlnectans), and Black-naped Monarch showed higher prey-ca1r'-capture rates when ibraging in mixed-species flocks than when outside flocks. Tire.'he Ashy Drongo (r. letcophoeus), Crcater Racket-tailed Dro[go, and Crow-billedIed Drongo changed perching positions significantly more offen in mixed llocks than ouloutside mixed flocks. .\nong the fou. sentinel species, kleptoparasitism behavior was most lrequently obseNed in the Ashy Drongo (14.7% oftotal foraging events) andmd least freque[tiy i11 the Black-naped Monarch (11.50/o of total foraging events). A man'rmalmal species. the \\iestern St ped Squirel (Iaalops mcclellandii). associated closel)rsely with bird flocks, and was itsclf 'a much more frequent early a11ti-predator alarmn callerca than the four abovementioned conventionally accepted sentinels. Future studiesdies should focus on lirrther assessing the specific benelits and costs to each species fromrom their participatiorl in tlocks.

KEY WORDS: MIXED-SPECIES FLOCK / HETEROSPECIFICIC ASSOCIATIONA / BIRD-WAVE / BEHAVIOML ADJUSTMEN,IFNT / SF,NTTNF,T, SPECIES / ANTI-PREDATOR VIG]LANCE

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CHAPTER I COMPOSITION AN'D STRUCTURE OF AVIAN MIXI,D-SPECIES FORAGING FLOCKS IN LOWLAND DECIDUOUS FORESTS, IIUAI KHA KHAENG WILDLIFE SANCTUARY

-{bstract

The numbers and species of birds participating in avian mixed-species :i.raging flocks in lowland deciduous forest were rccorded for a total of 657 flocks :kouehout the year in Huai Kha Khaeng Wildiife Sanctuary, Thailand. Most flock ranicipants showed a high propensity to associate with birds of similar body size.

Thus. flocks could be categorized into two main qpes, each compdsing different sets

.ri regular mixed-flocking species: those with small-sized birds as core species and tose rvith medium-sized bird species as core species. Resident species participated in rni\ed-species flocks more when non-breeding visitors were present (Aug-Jan) and e\hibited a lower propensity to join mixed flocks during the breeding season (Feb-

-lul). Distinct associations among particular species were identified and some engaged

:n specific behavioral roles in the flock. Three species in medium-sized bird flocks, Creater Yellownape (Chrysophlegma flavinucha), Black-headed (Picrs .alht op)igius), and Greater Racket-tailed Drcngo (Dicntrus paradiseus) perched signiiicantly lower in mixed-species flocks led by the gregarious and terrestrial ..lughingthrushes (Garrla.r spp.) than outside mixed-species flocks. Most findings in r.eYious studies were supported: mixed-flock paficipants were attracted tojoin flocks ot similar-sized species, mixed-flocking propensity was low in breeding season, and -.me species showed behavioral adjustments when participating in mixed flocks.

-{e)\\ords: Mixed-species flock, interspecific association, bird-wave, cluster analysis, :'eha!ioml adjustment \\ ichyanan Limparungpatthanakij Composition and Structure ofMixed-species Flocks / I0

:herc was only one height value per species during any given flock encounter. Al1 data

rrere collected by the author. Therefore, consistency in measurements was €nsured to some extent. For each mixed-flocking species, the perching height preferences of individuals participating in ("inside') and or not paticipating in (.,outside,,) mixed- .pecies flocks were statistically examined using the non-parametric Wilcoxon rank- ium test, often refered to as Mann-Whitney U test. The tr'-test was also applied in orJer to assess the differences in variances.

Nomenclature and follow the checklist of Thai bird names, -:ruary 2012 (BIRD CoNSERVATToN SoclETy oF THATLAND REcoRDs CoMMr|trjrl :,r1li.

Results

Composition and structure of mixed-species foraging flocks Data on bird species pafiicipating in avian mixed-species foraging flocks

.i.'re recorded for a total of 657 flocks throughout the year. A total of 37 out of 1 17 :-didate species were considered regular flocking species, having a mixed-flocking

::.'pensity exceeding 40% (Table 1.2). A few species seen rarely, but thoughr also to

^t possibly core-flocking species (e.g Bar-winged Flycatcher-shrike, Aerripa.e

.:-dnrr. and Verditer Flycatcher, Eumyias thalassinus) were excluded from the :::l\iis as sample sizes were too small (Table 1.3). Flock types could be broadly -.:.'sorized by the range of body sizes of participating species into 268 flocks of

::::.1ll-sized birds, and 384 flocks ofmedium-sized birds (Table l.l). The remaining 5 :::red'species flocks could not be decisively categorized by size. The groupings in the :-iir diagram (Fig. 1.3) conelated well with body sizes and mixed-flocking ::. aensitv. Wichyanan Limparungpatthanaki j Composhion and Slructure ofMixed-species Flocks / 30 etlciency with variation in flock size and composition. Improvements in testi.g and analyzing behavioral interactions among participants in mixed-species flocks will lead to better understanding of species roles and adjustments to mixed flocks, especially in the fast-moving small-sized bird flocks.

Conclusions

1. Flocks participants tended to associate with othcr species of similar body size. There were two main types of mixed-species lbraging flocks: small-sized and medium-sized bird flocks. Small-sized bird flocks consisted of both residents and migrants regularly containing BIack-naped Monarch, Grey-headed Canary-flycatcher,

Radde's Warbler, Yellow-browed Leaf Warbler, Two-baned Warbler, and Pin-striped

Tit Babbler. Medium-sized bird flocks only comprised resident species. White-crested Laughingthrushes and Lesser Necklaced Laughingthrushes predominated, and were

.joined by Green-billed Malkoha, Greater Yellownape, Black-headed Woodpecker, Common Flameback, Greater Racket-tailed Drongo, and Westem Striped Squinel. 2. The flocking propensity of resident species was lowest during the breeding season. Especially among flocks ofsmall-sized birds flocking propensity was much higher when non-breeding visitors were present. 3. Some species co-occurred in the same flocks most often with those othq species with which they shared similar foraging guilds, e.g., Rosy Minivet and Brown-rumped Minivet, White-crested Laughingthrush and Lesser Necklaced Laughingth.ush, and Grey-capped Pygmy Woodpecker and Velvet-fronted Nuthatch.

This was likely due to shared information on food resources- 4. Some species with similar coloration and pattem co-occured in the same flocks. These incllrded Lesser Yellownape and Greater Yellownape, Greater Flameback and Common Flamcback. and Yellow-browed Leaf Warbler and Two- baned Warbler. An underlying reason for such asocviations may be the reduoed individual's pledation risk tltough the dilution effect. 5. Thrce species that were reguiar inhabitants of medium-sized bird flocks (Creater Yellownape, Black-headed Woodpeckcr, and Greater Racket.tailed Dongo) pcrched significantly lower when lbraging in mixed-species flocks than outside llocks. Fac. of Grad. Studies, Mahidol Univ. M.Sc. (Environmental Biology) / 3l

6. Reduced variance in perching heights demonstrated among some pafticparts of small-bird flocks (Grey-capped Pygmy Woodpecker, Crow-billed Drongo, and Yellow-browed Leaf Warbler) implied that they were more restdcted to certain strata when foraging inside mixed-species flocks than outside flocks. Such reduced behavioural flexibility might possibly serve to reduce interspecific competition for resources among flock pa(icipants.

- Wichyanan Linparungpatthanakij Analyses ofBenefils and Costs Among Participants / 32

CHAPTER II ANALYSES OF BENEFITS AND COSTS AMONG MIXED- SPECIES FLOCK PARTICIPANTS

Abstract

Mixed-species flock participants are presuned to benefit from foraging in flocks through better anti-predator vigilance and increased foraging efliciency. Four species of ; i.e., Greater Yellowl,a'pe (Chrysophlegmu Jlovinucha), Lesser Yellownape ( chlorolophus), Black-headed Woodpecker (P etythropfgius), and Common Flameback (.Dinopi n ia\'anense), showed significantly lower vigilance rates in mixed-species llocks than outside. This may enable them to devote more time to feeding. Their vigilance rates were also regalively conelated with flock size. ''Sentinel species" are those species whose foraging mode (usually flycatclting fron elevated or exposed perches) supposedly assists them in adopting an cnhanced anti- predator vigilance role in nixed-species foraging llocks of birds. Three ol these scntinel species, Grcater Racket-tailed Drongo (D. poradiscus), Crow-billed Drongo lD. qnnectuns). and BIack-naped Monarch (Hypothymis azurea)- showed significartly higher prey-capture rates while traveling insidc mixed-species flocks (p-values < 0.05) than when feeding solitarily or with conspecifics. Together with a l-oufth sentinel spccies, Ashy Drongo (A kucophaeus) they exhibited various degrces ol kleploparasitism behavior. ranging lioir I 1.5o% frequency ofall prey-capture evcnrs 1n Black-naped Monarch to 14.7% in ,{shy Drongo.

Kcywolds: Mixed-species flock, interspecific association, bird-wave. klcptoparasitism. sentinel species, anti-predator vigilance Fac. ofGrad. Studies, Mahidol Univ. M.Sc. (Environmental Biology)/ 39 the total ntunbs of prey-capture events. The reactio!1 of the kleptoparasitism victim towards the sentinel species (i.e., flee, chase off, null, erc.) were also noted.

Results

Vigilance rates of woodpeckers There were only four woodpecker species with more than 8 samples on vigilance rates per minute in both outside and inside mixed-species flocks; i.e., Greater

Yellownape (Chrysophlegma ;/lavinucha), Less* Yellownape (Picus chlorolophus), Black-headed Woodpecker (P. eryihropygius), and Common Flameback (Dinopiun iavanense). Although vigilance rates of all four species inside and outside mixed- species flocks overlapped to some extent (Fig.2.3), they were significantly lower inside mixed flocks (p < 0.05) using Wilcoxon rank-sum test (Table 2.1). Mean (ilSE) vigilance mtes (vigilance behaviors per minute) outside mixed-species flocks

\iere 6.33+0.67 oy' = 12), 8.00+0.99 (N: 9), 8.24+0.86 (N : 17), and 6.1 1+0.64 (-rr' = 17) for each species respectively. The frequencies of vigilance behaviors while fbraging inside mixed-species flocks were reduced by roughly four occasions per minute; 2.53+0.53 (N : 23), 4.07+0.62 (N : l4), 4.21+0.47 (N = l9), and 2.24:0.4'7 (N= 27) respectively (Table 2.1).

Table 2.1. Vigilance rates per minute of fottr most common woodpecker species (measured by counting the frequency of vigilant behaviors such as head-cocking. head-turning, and iooking-up).

Outside mixed-flocks lnsidemixed"flocks Wiicoxon Species name Mean 1 SE N l,lean l SE N P value Grealer Yellownape 6.33 r 0.67 12 2.53 t 0.53 23 0.002167 Lesser Yellownape 8.00 t 0.99 I 4.07 t 0.62 14 0.002855 Black headed Woodpecker 8.24 r 0.86 17 4.21!0.47 19 0.001311 Common Flameback 6.11 t 0.64 17 2.24 !0.47 27 0.082x10s Fac. olGrad. Sludies. Mahidol Univ. M.Sc. (Environmenlal tsiology) / 57

Drongos are known for their aggressive nature (PAYNE 1967). Likewlse, they also regularly showed aggressiveness towards conspecifics, mobbing and emitting alam calls in territorial defence. The latter behavior was apparently beneficial to eavesdropping species in the same heterospecific flock. All three drongo species analyzed in this study showed higher kleptoparasitism propensity than the Black-naped Monarch. fhe three drongo species also invested energy in changing pcrching positions significantly nlore often inside mixed-species llocks than outside. In order to Llncover moLe detailed beneflts and costs of each participant in mixed- species llocks, the behaviors of dillerent species in l'uture studies must be studied nlore thoroughly both inside and outside mixed-species llocks. This ilc]udes the

somcwhat complicated niche partitioning among species with similar lbraging guilds, and the causal stimulus behind different types of close-association heterospecific interaclions.

Conclusions

1. Four woodpecker species, Greater Yellownape, Lesser Yellownape, Black-headed Woodpecker, and Commo[ Flameback, showed signilicantly lowcr \ iqilance rates r,r'hen l'eeding ir mixed-species flocks than when outside llocks. Their \ igilance mtes also declincd as flock size increased. This implies they bencfit {iom loining nixed-species flocks through coryorate vigilance. 2. Three out of four sentirel species for which there was adequate data. Creater Racket-lailed Drongo, Crow-billed Drongo, and ulack-naped Monarch. sho*ecl signilicantly shorter time intervals between successive pr'ey captures when leecling in mixcd-species flocks than when fceding outside flocks. TIlis suggests they bencfited from the "beater etfect" which enabled them to feed on insects flushed by

olher flock parlicipants. Ashy Drol]go, Greater Racket-tailed Drongo. and Crow-billed Drongo were found to changc perching positions significantly more oiten nhen inside tlocks. so as to move synchronously \,ith other pa icipants in rnixed-species loraging llocks. 3. The foraging efficiency of some sentincl species in mixed-sFecies

llocks r.vas incrcascd by kleptopatasitism bchavior. Tluee speoies of drongos ard thc

I wichyanan Limparungpatthanakij Analyses ofBen€fits and Costs Among Participants / 58

Black-naped Monarch, all of which ere presumed to act as "sentinel species" stole food items ftom other birds. Kleptoparasitism propensity was highest in Ashy Drcngo (14.7%), followed by Grcater Racket-tailed Drongo (13.0%), Crow-billed Drongo (11.7%), and Black-naped Monarch (11.5%). The Grcater Rackeltailed Drongo

victimized Lesser Necklaced Laughingthrush, Common Flameback, ard other Greater Racket-tailed Drongos most often. The Black-naped Monarch most frequently targeted other individuals ofits own kind.

Er---.- Fac. of Grad. Studies, Mahidol Univ. M.Sc. (Environmental Biology) / 59

CHAPTER III THE ROLE OF WESTERN STRIPED SQUIRREL (?AMIOPS MCCLELLANDII) IN AVIAN MIXED-SPECIES FORAGING FLOCKS

Abstract

'fhe Westem St ped Squinel (Tauiops ncclellandii), a small arboreal scluirrel inhabiting forests in the Himalayas and mainland , often accompanied avian mixed-species foraging flocks. ln a total of 70 observations that involved responses by flocks to predatoN, the Westem St ped Squirel emitted alarm calls on 40 occasions (more than any other flock-associating bird or mammal). It was

the first to alarm call on 24 occasions (600%), the second for 11 occasions (28%), and

the third onwards for 5 occasions (l3olo). This species was most frequently involved in

close-association with d.ongos (ric,.r,"r,j spp.), which have been traditionally regarded as "sentinel species", supposedly playing a role in antipredator vigilance in mixed- species flocks. Yet drongos and other avian "sentinels" (5 species combined) uttered the first alarm calls on only 14 occasions. Mixed-flock pafticipants benefited from the presence ofthe predator-sensitive Westem Striped Squirrel. However, the squirrel and other mixed-flock panicipants probably benefited fiom the drongos' tendency to nlob and chase away predators. At the same time, drongos followed the bark-gleanirlg Western Striped Squinel to pursue adhropods flushed by their movement along the branch. Ihis suggests that the presence ofthe Western Striped Squinel both helped reduce the need fbr vigiiance arnong other flock members and was in1portant lor flock cohesion

Keywords: Mixed-species flock, squinel, anti-piedator alarm call, anti-predator vigilance, serltinel species, interspecific interaction

- Wichyanan Limparungpatthanakij The Role of Westem Striped Squinel in Mixed Flocks / 64

recorded. The main foraging modes were categodzed into four differcnt foraging guilds: arboreal foliage gleaners, bark gleaners, terrestrial foragers, and flycatching foragers.

Results

Occurrence of mammals in mixed-species bird flocks A total of six small mammal species foraged with avian mixed-species foraging flocks: five species of diumal squirrels (Fam. Sciuridae) and one species of teeshrew (Tupaiidae). When foraging with avian mixed-species flocks, all mammals showed a significantly greater tendency to join flocks ofmedium-sized birds (in which laughingthrushes and woodpeckers predominated.) than flocks of small-sized birds (Pearson's Chi-square p-values < 0.05). The Westem Striped Squirel and the semi- tereshial Northem Treeshtew (Tupaia bela,?geri) showed the highest mixed-flocking propensity (67% and 610z respectively). Other occasional flock joiners were Indochinese Ground Squinel (Menetes berdmorei), Pallas's Squinel (Callosciurus erythraeus), and Grey-bellied Squirrel (C caniceps) (Table 3.2). These had mixed- flocking propensity of 38%, 31yo, and 2lyo respectively. The largest species, Black

Giant Squirel (Ratufa bicolor), only showed 5olo mixed-flocking propensity (Table 3.1). and its occunence with avian mixed-species flocks was possibly accidental. Most often, no more than one or two individuals of each mammal species were encountered in any one flock (Table 3.1).

In addition, therc were a few cases where medium-sized bird flocks were observed foraging in the vicinity of Phayre's Leaf Monkeys (Trachypithecus phayrei) and ungulates such as.the Wild Boar (Sus scrolit), Common Mundac (Muntiocus mtmtjak), Sambar (Rusa unicolor), and Banteng (Bos iavanicusl. Such incidents occured most regularly between large ungulates and monospecific flocks of Red- billed Blue Magpies (U/ocis.ra erythrorhynchct), which apparently fed on parasitic inve ebrates such as ticks, lice, and fleas. In spite ofthis, there did not appear to be any cohesive synchronous movements among mixed-species bird flocks and these mammals. Fac. ofCrad. Studies, Mahidol Univ. M.Sc. (Environmental Biology) / 73 of their palticipation in bird flocks seems to have been underestimated. It is not unexpected if future studies Iind other mammals, particularly small sqLrinels, playing similar behavioral roles in avian mixed-species flocks to the Westem Striped Squinel. Recommendations on further studies include: 1) Expe ment using playback methods to test the responses by mixed-flocking species to vocalizations of Westem Striped Squirrel, sentinel species, and the combination of both. 2) Comparison between prey- capture rates per change of perch of sentinel species when associated with bark- gleaners and non bark-gleaners.

Conclusions 1. The Westem Striped Squinel played an influential behavioral role in avian mixed-species foraging flocks as the most frequent early anti-predator alam caller. 2. The Westem Striped Squi.rel was the most frequent co-forager of drongos, which are regarded as sentinel species important in mixed-flock initiation.