Does territory owner aggression offer an alternative explanation to patterns in heterospecific information use studies? A comment on Slagsvold and Wiebe

Abstract

Slagsvold and Wiebe (2017) criticize part of the literature on heterospecific information use, coined the interspecific cue hypothesis (ICH), which use geometric symbols to study whether flycatchers copy or reject the apparent choices of tits (Seppänen and Forsman 2007, Forsman et al. 2012, Loukola et al. 2013, Jaakkonen et al. 2015. They claim that some of the heterospecific social information use patterns in flycatchers as revealed by these apparent novel niche experiments (ANNE) can instead be explained by tit aggression. They introduce the owner aggression hypothesis (OAH), which proposes that tits aggressively defend alternative nest boxes, which may better explain the patterns that were previously interpreted as heterospecific information use. Slagsvold and Wiebe (2017) present the number of assumptions of the OAH as smaller than that of the ICH, essentially claiming that this provides a more parsimonious explanation for the patterns observed in the ICH literature. Although the owner aggression hypothesis is interesting and needs to be tested, there are still a number of patterns in the heterospecific information use literature that cannot be explained by tit aggression. Moreover, I do not agree with some of the arguments used to reject the ICH, and the number of assumptions of the OAH may be higher than claimed in the paper, undermining the claim that it is more parsimonious than the ICH.Tits and flycatchers share many resources in the same environment, from nesting holes to food sources like caterpillars. They also have common threats including aerial predators like sparrow hawks Accipiter nisus and nest predators like pine martens Martes martes among others. Considering the degree of niche overlap, it would be surprising if the later breeding migratory flycatchers should not use information from the presence of the earlier breeding resident tits. Moreover, tits spend the entire year in (the vicinity of ) the breeding grounds, in contrast to flycatchers, which spend the winter in Africa and can benefit from social information provided by the better informed tits. There is ample evidence that flycatchers use the information of tits in their settlement and reproductive decisions (Kivelä et al. 2014, Jaakkonen et al. 2015, Samplonius and Both 2017. Experiments with the apparent copying or rejection of geometric symbols (Seppänen and Forsman 2007, Seppänen et al.

On heterospecifc learning in birds – comments on Samplonius and Forsman et al

“…We termed this the interspecific cue hypothesis (the ICH; Slagsvold and Wiebe 2017) and argued that some of its basic assumptions have never been critically examined. Forsman et al (2018) and Samplonius (2018) criticize our paper and argue that the ICH is the most plausible explanation but here we conclude that the new data they provide on the behaviour of the pied flycatcher (Forsman et al 2018) are, in fact, inconsistent with the most critical assumption of the ICH. Therefore, the hypothesis should be rejected.…”

“…In our point-of-view paper, we acknowledged that the critical assumption of the OAH, that tits aggressively defend extra nest sites 25 m from their current site, must also be tested in the field. Forsman et al (2018) and Samplonius (2018) do not provide evidence that tits are never aggressive to flycatchers trying to settle close by. Samplonius (2017) mentions that tits at Oxford travelled farther than 25 m to renest but this doesn't take into account the spatial arrangement of boxes available to the tits.…”

“…Also, natural cavities used by the tits are usually much deeper and darker than nest boxes making counting of eggs more difficult (Wesolowski and Maziarz 2012). Samplonius (2018) cites some studies on captive birds, but whether the counting performance of a few trained birds in lab situations reflects widespread counting ability in birds in challenging natural contexts needs to be confirmed. Regardless, the ICH can be rejected because the main assumption, that of nest visits, fails as argued above.…”

Is it interspecific information use or aggression between putative competitors that steers the selection of nest‐site characteristics? A reply to Slagsvold and Wiebe

“…As intriguing as Slagsvold and Wiebe's (2017) hypothesis is, several lines of reasoning suggest that, without any further evidence for the assumptions of the OAH (see above), it is not a more plausible hypothesis than the SIIU for four reasons (see also Samplonius 2017).…”

On resolving the selective interspecific information use vs. owner aggression hypothesis dilemma—a commentary

“…Several arguments raised against the selective interspecific information use hypothesis have already been addressed and it is clear that for now favoring the owner aggression hypothesis over the selective interspecific information use hypothesis would be premature Samplonius 2018). However, there are points that still remain open in the ongoing debate, related to flycatcher prospecting behavior and cognitive abilities to assess tit clutch size, which call for urgent research attention.…”