Recurrent seasonal occurrence of the Lineated Woodpecker ( Dryocopus lineatus (( ) in a riparian frag m ent ss of the A tlantic Forest, northeastern Brazil

A BSTR A CT: Riparian forests play important roles as ecological corridors and refuge habitat for many bird populations in fragmented landscapes. This report describes the seasonal occurrence of the Lineated Woodpecker ( Dryocopus lineatus ) in a small ss riparian fragment of Atlantic Forest, northeastern Brazil. A female was recorded by its visual and acoustical signals from September to October 2014. Similar occurrences were observed in the same months over three consecutive years. Two major hypotheses regarding the woodpecker seasonal occurrence are discussed here: i ) the use of the riparian fragment for breeding, evidenced by tree-cavity nests; and ii ) fleeing of the bird from its natal habitat due to fire in adjacent sugarcane fields, which commonly are burned in these two months. Such recurrent events suggest that D. lineatus uses the riparian fragment as refuge habitat, highlighting the importance of these environments for bird populations that inhabit fragmented landscapes of the Brazilian Atlantic Forest.


INTRODUCTION
Riparian forests are interface zones between terrestrial and aquatic systems characterized by high nutrients cycling and flood-influenced seasonal resources (Naiman & Décamps 1997). Birds use these environments as ecological corridors for crossing habitats and as refuge for feeding and breeding (Knopf & Samson 1994). In Brazil, the riparian forests are essential for maintenance of bird fauna in fragmented environments (Anjos et al. 2007), hosting increased species richness in rivers with larger riparian margin width (Ramos & Anjos 2014).
The Brazilian Atlantic Forest is recognized as one of the major biodiversity hotspots around the world (Myers et al. 2000). Historically, the domain has largely been reduced to fragmented landscapes as a result from human-disturbances, with only 11.7% of its original coverage remaining (Ribeiro et al. 2009). Despite highly fragmented, the northeastern region of the Atlantic Forest (known as Pernambuco Endemism Center) shelters a rich and endemic avifauna (Silva et al. 2004)  inhabiting the Pernambuco Endemism Center than other areas. Woodpeckers (Picidae) are forest-dependent birds, in which the species richness is closely associated with tree cover (Ilsøe et al. 2017), being widely used as bioindicators of changes in forest structure (Mikusiński 2006, Vergara-Tabares et al. 2018. The Picidae is a speciose group across South America with c. 83 species (Erize et al. 2006) that display key ecological roles as builders of treecavities (excavators), which are used as nests for many species (Cockle et al. 2011, Gorman 2014. The Lineated Woodpecker Dryocopus lineatus (Linnaeus, 1766) is a s tropical widespread species, ranging from Mexico to northeastern Argentina (Malekan 2011, Gorman 2014. In South America, it occurs in Argentina, Bolivia, Paraguay and throughout Brazil (Sick 1997), from the core to edges of the forest fragments (Stotz et al. 1996). Its acoustical signals are easily identifiable, especially when drilling soft-woods (drumming) for feeding on small insects, such as ants and beetles (Malekan 2011).
This report describes the recurrent seasonal occurrence of D. lineatus in an Atlantic Forest riparian fragment, northeastern Brazil. Because similar events occurred along years (2015, 2016 and 2017), always between September and October months, we suggest that the woodpecker uses the riparian fragment to refuge for breeding or escaping from the burning of sugarcane fields around its natal habitat.

METHODS
A female of D. lineatus was photographed ( Fig. 1) on 23 September 2014 at ~07:50 h in a small riparian fragment of Atlantic Forest of the Pernambuco Endemism Center at the Santa Rita municipality, Paraíba state, northeastern Brazil. Its sex was determined by the presence of a black spot on the anterior region of the head and by the absence of a red stripe on the cheek (Erize et al. 2006). It remained ~5 min on a branch of a Cecropia palmata tree, foraging on small insects (ants). For this record, researchers (R.M. and G.M.P.) were at the exact point (7 o 10'16.2''S; 35 o 00'12.9''W), where local residents had previously reported sighting the bird. A playback sound with the laughing call of the species (download freely from WikiAves) was used for attracting the woodpecker, as a response to the territorial behavior (Gorman 2014). The site is a farm with 74 ha (c. 70% of forest cover) surrounded by sugarcane fields and pineapple plantations. The vegetation is typical of secondary stage composed by a high abundance of Arecaceae, Cecropiaceae and senescent trees. Tibiri River crosses the forest fragment entirely ( Fig.  2A) forming microhabitats similar to floodplains and wetlands in some areas.

RESULTS
Visual and acoustical signals of the bird were recorded until October 2014 and ~6 tree-cavity nests (Fig. 2B) were accounted in the area. The most common sounds were territorial calling and drumming. Sighting of the woodpeckers were reported by local residents on each consecutive year (2015, 2016 and 2017) after the initial record in 2014, including a low-resolution video provided by one of them in 2016 (supplementary material). They also reported that the detections of the bird started in September and lasted until October, with often more than one individual observed at the same time. The authors validated the information provided by residents by showing photos of the bird (i.e. species identification) and inquiring about the record (e.g., microhabitat,  woodpeckers are probably large forest remnants of legal reserve (i.e. 20% of preserved native forest within a property) belonging to sugarcane companies, which are located closer to the riparian fragment. In this sense, the bird fled from its natal habitat to the riparian fragment in order i) to avoid fire-caused injuries (Lyon & Marzluff 1985); or ii) to increase the forage on small invertebrates that escape to the forest patches nearby the fire-disturbed area (Vasconcelos et al. 2009). Fire effects on birds are species-specific and the harms increase with high-severity burning (Barlow et al. 2002(Barlow et al. , 2006. The landscape connectivity facilitates the bird movement among nearby forest fragments (Uezu et al. 2005), and this has been recorded for large-bodied woodpeckers, such as D. martius (Gil-Tena s et al. 2013) and Campephilus magellanicus (King, 1828) (Vergara s et al. 2019). Recent studies have documented that woodpeckers disperse to neighboring patches mainly for foraging activities, with the movement decision influenced by the habitat quality (Vergara et al. 2015(Vergara et al. , 2019. It is likely that D. lineatus used the riparian vegetation as an ecological s corridor for crossing from its natal habitat to the patch site. Indeed, riparian corridors have been shown effective for movement among habitats for forest specialist birds (Gillies & Clair 2008). However, there is no study that reports seasonal movement behavior or dispersal ability for the species up to date, which raises the need of monitoring studies to understand patterns of use of forest patches by these birds.
The seasonal occurrence of D. lineatus in the s riparian fragment suggests its use as refuge habitat, but the available information is insufficient for an unbiased definition regarding the two hypotheses on the ecological drivers operating at the population level. Further observations on breeding habits and the use of mark recapture techniques are required. Such recurrent events highlight the importance of river-edge environments for forest-dependent birds that inhabit fragmented landscapes of the Brazilian Atlantic Forest. sounds, size). It is worth mentioning that only piculet species (Picuminae, Picidae) occur in the area, with the absence of larger woodpeckers that could be confused with D. lineatus [ s e.g., Crimson-Crested Woodpecker Campephilus melanoleucos (Gmelin, 1788)]. The same local ancient residents claimed that the occurrence of woodpeckers is very recent in this area, because they were never seen or heard them before 2014.

DISCUSSION
The recent appearance of woodpecker can be related to well-preserved traits of the riparian fragment, as supported by occurrence of other birds [e.g., Aramides cajaneus (Statius-Muller, 1776), Porphyrio martinicus (Linnaeus, 1766)] and mammals [e.g., Lontra longicaudis (Olfers, 1818), Dasyprocta spp.) indicators of healthy environments. The high habitat heterogeneity in riparian fragment (e.g., dead tree areas, Cecropiaceae soft-wood zones, and floodplains) may also be an ecological driver for the species presence. In corroboration, recent studies have shown that Dryocopus martius (Linnaeus, 1758) uses a wide variety of forest environments in the Italian Alps (Bocca et al. 2007), D. lineatus prefers dead tree areas (snags) in Santa Fe de Antioquia/Colombia (Granada-Ríos & Mancera-Rodríguez 2015) and D. pileatus (Linnaeus, 1758) has the home range limited by the snags abundance in lowland forest of the United States (Tomasevick & Marzluff 2018). Although the riparian fragment is relatively small, the high preservation degree coupled with habitat heterogeneity, especially dead tree areas, may have promoted the immigration of the woodpecker.
Two major hypotheses are addressed here for the woodpecker seasonal occurrence. First, D. lineatus used s the riparian fragment as breeding refuge, as individuals were observed using the tree-cavity nests in 2014 (R.M., pers. obs.). The use of nests was also reported by local residents on each year (2015, 2016 and 2017) between September and October months. Different breeding periods have been documented for D. lineatus around s the world, including March-April in Panama, April-May in Belize (Caribbean) and February-April in Trinidad and Suriname (Malekan 2011). These records reveal a short-time breeding (2-3 months), which sustain the hypothesis of breeding-related seasonal occurrence. Nevertheless, comprehensive information on biology and ecology of this species is scarce in Brazil, especially on breeding, nesting and roosting.
Secondly, the woodpecker dispersed to the riparian fragment driven by pre-harvesting sugarcane burning around its natal habitat. The region harbors large sugarcane fields and the burning practice commonly occurs over September and October. Natal habitats of