My dog has started shedding her winter fur early this year due to the warm weather.
Typically, I place the combed-out fur in the backyard for the birds to pick if they wished so.
This year, as I brought the fur out in the garden, I began noticing that there were not yet as many small bird species around as in the spring of the previous year (2023).
I have heard the larger birds returning (swans, geese, cranes) and I have seen flocks of waxwings that are temporary travellers through Latvia.
Blackbirds are also back (I am not certain how far they migrate but the true thrushes that live in our backyard can only be observed starting from spring and they do not seem to hold residence during winter).
Other species, however, are still largely absent.
I have not looked up specific research discussing the changes in migratory behaviour in smaller songbirds, but, from observations alone, it seems that the larger migratory birds react more closely to the current climate by synchronizing their arrival with the conditions of the specific year.
Meanwhile, smaller birds do not seem to have caught up as quickly during this very early spring.
It might cost survival and reproductive success if small birds returned to their breeding areas prematurely (when significant cold spells might yet occur) compared to larger birds who due to their larger size might be more hardy.
However, I would not make any strong claims before I have familiarized myself with the accumulated evidence.
From observations alone, I began wondering whether the shifts in spring temperatures might affect the amount of fur accessible to smaller (and medium-sized) birds as nesting materials if the mammals moulted their fur much earlier than the smaller-sized migratory birds returned.
This likely depends on the cues that onset moult in mammals.
For example, both temperature and photoperiod might be implicated as those are environmental variables influencing hormones but it is through the hormonal pathways, the moulting process is activated.
I suppose that both pathways might interact and that the moulting occurs by degrees.
However, if moulting depended on temperature and/or the intensity (actual amount) of radiation (rather than the number of daylight hours during which some might be sunnier than others), mammals would likely start shedding their fur earlier than they used to, historically speaking.
If photoperiod itself (the duration of daylight vs. dark during diel cycles) determines moult, the onset would not be affected.
Dogs are no longer wild animals, and I do not suppose that shedding fur in dogs follows any environmental pattern.
At least I have observed some of the dogs that are kept exclusively outside keeping their winter fur for much longer than other dogs who live both inside and outside, and some ‘indoors dogs’ do not seem to accumulate much insulation at all.
Thusly, dogs might be adapted to the actual temperature conditions and living conditions rather than seasonal hormonal fluctuations in accordance with ambient temperature (or radiation) only.
Namely, it is possible that a dog would start shedding before other wild mammals simply because the mammals live out in the colder environment and because they have certain physiological adaptations which are not altered as easily.
If wild mammals who are fur-donators, however, react to temperature cues, I believe that my dog is a good indicator because while she sleeps and rests indoors, our house is fairly cold and warms up very slowly during spring, and she also spends a lot of time outside during early morning or even night hours.
In such cases, mammals might shed their fur before the smaller birds arrive and while fur is not degraded quickly, it might become contaminated with parasites and pathogens as well as soaked with dampness which makes it a worse nest-building material.
On the other hand, if photoperiod determined the onset of moult in some mammals but the smaller migratory birds adjusted their return to the earlier spring warming (not as greatly as to arrive with the first warm weeks but still arriving earlier than ‘usual’), these birds might return before the moult begins and, once more, if they begin constructing their nests quite right away, the fur might not yet be accessible from these photoperiod-based moulters.
I am writing this to note that I should look up research on the following topics:
- Do smaller birds adjust their migratory behaviour to current weather rather than long-term climate differently than larger birds?
- Do most mammals begin their moult in accordance with temperature, amount of radiation and/or photoperiod and how it affects the timing of the onset of the moult?
In fact, if mammals began their moult (and other activities) in response to photoperiod predominantly (as observed in some Mustelids where the number of daylight hours can override temperature implications), the climate change could affect a number of their behaviours and strategies (thermoregulation, camouflage, use of habitat to find shelter etc.).
Notes by Ieva 